All cat sailors

Hi everyone,
I am doing a school projected on catamarans, I sail a dart 16 but need to get more information on all the other cats. I am currently researching on the design defaults or problems with high proformance cats, so if you spare some time to give me the name of the cat and any design defaults or problems with the cat then I would be very greatful ( if you know of any solutions to the problems on the cat then can you please add)
thankyou!!!

Solution:

Outsource the manufacuring to Malaysia. The big sail lofts are doing it!

Search this forum for the following key words and you will find lots of information:

too heavy
forward buoyancy (lack of)
pitchpole
not wide enough
not long enough
overcanvassed
undercanvassed
small sail area
big sail area
short mast
tall mast
righting moment
broke

Good luck,

find Bill Roberts. He'll educate you on all the flaws of every catamaran on the market (whether you care to know or not) :P

Speaking of Bill Roberts, I have not seen him on this forum for some time now. I hope he is still with us, as he is an experienced designer and sailor. (Even if not everybody agrees with him on all issues).


Faults with cats:
The Tornado has the fault that it is to expensive if bought new from Marstrøm. To wide to trailer without disassembly. Otherwise it is the perfect cat in my eyes

A common fault of all cats, are that sails are _very_ expensive. (I tought this was what Norths 3DL technology initially was meant to fix).

That about covers it!

If you are interested in the some of the design philosophies of Bill Roberts you can do a search on the open forum here under his name. Also go to http://www.aquarius-sail.com/. (The boat builder of his designs).
There is much information on the individual products, and also a ARC/Supercat owners forum, to which he frequently responds...Between the posts he has made on this forum and the Aquarius Site you can get a wealth of information on his approach to solving some of the reoccurring common problem in small cat design...

Topics such as:

Why he uses full volume, elliptical shaped bows to dramatically reduce the propensity to pitch pole. A problem that is common with cats having flat fore decks, or cats with insufficient bow volume and flat fore deck such as a Hobie 14 and 16.

His "Shared lift Concept" to help counter act the effects of sailing with a spinnaker on the helm.

Why he believes wider than trailer able width (8'-6" in the US) is desirable to break the performance barrier that has keep the 8’-6” wide beach cat from going on to the next performance level.

His "Self Tacking Jib" system. To help the boat respond faster with more efficiency and less effort.

His use of a mast section with sufficient volume (buoyancy) to keep his cats from going "turtle" in most circumstances.

A unique righting system that uses side stay extensions to allow the boats own weight to help right itself in the event of a capsize. This feature allows his 17' design to be righted by a single 160 lb person instead of the 300 lb crew weight it would normally require to right a 8' wide boardless beach cat.

These are just a few of the common problems he has addressed. He is an aeronautical engineer with a lifetime of experience. He is also an awesome sailor, which is easily supported by his winning record.

For example this past year he and his son Eric won a major distance race (Dec 2003 Steeplechase) with a worn 1981 Supercat 20 (one of his first production cat designs) which was 100 lbs over its minimum allowable racing weight (usually a racer wants to be “dead on” the minimum boat weight, and most would see it as a waste of time to race in a boat with such a severe weight handicap). He did this against some of the best sailors sailing some of the latest and greatest boats, winning by a wide margin, Winning both first to finish and on corrected time.…

He then went out a few weeks later with a “boardless” ARC 17 (also one of his designs)and won the overall open class in a major Buoy Race (Jan 2004 Tradewinds Midwinter Open Cat Nationals) against well respected racing cats of current design with dagerboards (dagerboards are regarded as a major advantage in sailing up wind), including the Taipan 4.9 and a Hobie 20.

He is an amazing person to talk to…he has the ability to cut thru all the hype and get right to the core or the problem. While many other designers treat the symptom, Mr. Roberts puts his energy into curing the underlying problem, which causes the symptom. For reasons I do not understand, much of the catamaran community has chosen to ignore his race proven advancements, and still struggle with fundamental design issues that Bill Roberts resolved decades ago…
A study of his Catamaran design history pretty much covers everything you said you were looking for in identifying and correcting problems in the beach cat design.

Good luck on your project...

Bob

They all do what they were designed to for a given use. If you use one for something it wasn't really designed for then some feature is going to look like a flaw. There are compromises to be made when designing for various conditions.
for example no boards is a flaw if your are racing upwind against a boat with boards. centerboards are a flaw if you are racing against a boat with highperformance daggersboards. while daggerbds. are a flaw if sailing around soals or reefs. flat rocker is an advantage in smooth water and for speed (if done right), but it's a flaw in the surf. acres of sail area is a flaw in strong wind, but an advantage in light wind. it is a flaw to put a beam on the bows of a boat that tends to sail bow down in a breeze, but the front beam is an advantage for light to moderate wind. it is a flaw to make a boat for strong wind and rough seas, but fail to have a way of adding footstraps.
hope this helps.

I think some clarification is in order here :

Seeker wrote :

>>For reasons I do not understand, much of the catamaran community has chosen to ignore his race proven advancements, and still struggle with fundamental design issues that Bill Roberts resolved decades ago…

The reason for this is that Bill is in error concerning several design aspects. It has been discovered by various designers that not all Bill says is actually true. On particular path of error is that Bill sees only one solution to a given problem while any good designer knows that often multiple solutions exist for a given problem and that a few of those achieve identical results. Still he will maintain that his prefered solution is the only one and all others are misguided.

In addition to this you make a few statements that are simply wrong or deceiving.


Topics such as:

>>Why he uses full volume, elliptical shaped bows to dramatically reduce the propensity to pitch pole. A problem that is common with cats having flat fore decks, or cats with insufficient bow volume and flat fore deck such as a Hobie 14 and 16.


Both the H14 and H16 are bad examples of the current state of cat design. Counterexample; nacra Inter 20 and inter 18 have flattish decks near the bow, neither are prone to diving or even has a bad characeristic in this sense. Actually the Tornado hull shape suffers more from a dive tendency than the equal length Inter 20 while the Tornado has more narrow decks and both are flat on top.

Eliptical hulls have been tried by other designers and since then they have moved on to other hullshapes that are superior to the elliptical ones. On big drawback of elliptical crossections seems to be the spray that comes of them.



>>His "Shared lift Concept" to help counter act the effects of sailing with a spinnaker on the helm.

OF which many sailors and designers by now have stated that it is NOT an issue on modern boats. Bill's simplified model assumes that a spinnaker introduces alot of lee helm on spi boat when in fact IT DOESN'T. Believe me, we've been there, tested it and the change in helm is hardly noticable and we used UNBALANCED rudders, so no camoflaging. It's there but SO SMALL that it is NOT a significant issue requiring a dramatic change in hull design. In fact the chance is welcome in that you want a boat to have a very small amount of leehelm under spinnaker. Bill will never accept that.


>>Why he believes wider than trailer able width (8'-6" in the US) is desirable to break the performance barrier that has keep the 8’-6” wide beach cat from going on to the next performance level.

I believe that Cheyenne with beat any 8'6" cat on the market today in all-out speed but that is not the point is it. We are talking about the best beachcat setup with means that things like practical trailoring and overall weight become important considerations. It is not that other designer don't agree with Bill that wider and longer will make a boat faster but that they disagree on what makes a commercial attractive design. I say that the differences in boats sold clearly shows who is more in tune with the market in this respect.


>>His "Self Tacking Jib" system. To help the boat respond faster with more efficiency and less effort.

Is not the superior setup that you make it to be. Other designers have since then progressed on this issue and yet others again are working on improving on these newer setups as well. Bill uses a straight track and that is arguable inferiour. And believe me no amount of special pully system can make a straight track as good as a properly designed curved track.


>>His use of a mast section with sufficient volume (buoyancy) to keep his cats from going "turtle" in most circumstances.

Gee man, I thought that all cats, excluding the Hobie 14, had this feature implemented. Even the cats that are older in design than the SC / ARC products had this so I guess Bill was not the first to think this one up.


>>A unique righting system that uses side stay extensions to allow the boats own weight to help right itself in the event of a capsize. This feature allows his 17' design to be righted by a single 160 lb person instead of the 300 lb crew weight it would normally require to right a 8' wide boardless beach cat.


A good designer designs a boat that can be righted without aids. But I think I will install sidestay adjuster on my A-cat now. Not to mention that there is a whole range of different aids available that all allow a 160 crew to right a two-person boat solo. Like I said there are more solutions to a single problem. Of course the modern solution is to make the mast and platform lighter and negate the need for aids altogether. Bill is yet to cross into this area of development.



>>For example this past year he and his son Eric won a major distance race (Dec 2003 Steeplechase) with a worn 1981 Supercat 20 (one of his first production cat designs) which was 100 lbs over its minimum allowable racing weight.

I seem to remember that it also had an oversized rig and was lucky to get its noose in a different weather system. The second day teh baot was beat by I think 9 I-20's on elapsed time. Its lead of the first day so such that it still corrected out over the whole event. But it show that either it had a very bad second day or a very good first day; both of which are no proof that the boat is vastly superior no matter what.


>>(usually a racer wants to be “dead on” the minimum boat weight, and most would see it as a waste of time to race in a boat with such a severe weight handicap).

It has been said many times, including by Bill himself, that the SC handicap ratings had drifted up (as if the baot has become slower) from the rating it was assigned 15 years ago. So please don't claim the SC has a severe rating because it simply doesn't.


>>He did this against some of the best sailors sailing some of the latest and greatest boats, winning by a wide margin, Winning both first to finish and on corrected time.…

Sighting one migrating bird doesn;t make a spring and the conditions during that distance race were suspect. A counter example is that the 2 SC product that have been entered in the round of texel for over 20 years now have never managed to win line-honours or win on corrected time. And here the best of world trully gether.


>>>He then went out a few weeks later with a “boardless” ARC 17 (also one of his designs)and won the overall open class in a major Buoy Race (Jan 2004 Tradewinds Midwinter Open Cat Nationals) against well respected racing cats of current design with dagerboards (dagerboards are regarded as a major advantage in sailing up wind), including the Taipan 4.9 and a Hobie 20.


There were 7 boats in the open class of that MAJOR (?) bouy race and ARC was assigned a peachy handicap number of 71.2; The others like H20 and taipan were racing of 64.9 and 68,1 and other lower ratings except the Dart 18. For such a superior design it is funny to see it rated between 10% and 5 % slower than its supposedly "inferior" competitors. It was beaten several times to the line by these boats that have about 15 % less sailarea than the SC17. More sailarea and still being rated significantly slower, that is some superior design you have there.


>>He is an amazing person to talk to…he has the ability to cut thru all the hype and get right to the core or the problem.

I grant that he is an amazing person, but about the hype I beg to differ. I think he actually spreads more of it than he debunks. The whole leehelm under spi is one major example; Eliptical bows is another. Ever noticed how in all pictures of the ARC-17 on the acquarius website the bow is almost under water, without the crew trapezing and on absolute flat water ? Humm, In never drive my bow down that far in such conditions and if I do than I start looking for hull leaks.


>>While many other designers treat the symptom,

Other designers have created very large and succesful classes like the H16, dart 18, F18, A-cat and Tornado classes. Also the new dsigns have breached serious barriers in lightweight construction and all-out speeds for a fraction of the SC and ARC prices and given teh limits imposed on these designs by reasonsof being easily trailerable. Not to mention that these design hold as good as all current records. And now you ask us to beleive that THEY got it all wrong ?

Wouter

A big problem with the high performance cats is robustness, they break way to easy. Most Holiday companies won't use them for that reason. That is why boats like your Dart 16 and the Hobie Wave are so popular.

The high performance boats are ok for racers and people who are willing to look after and maintain their boats, but the "plastic" hulls are better suited to the more recreational users.

There are new plastics and manufacturing methods that are beginning to be used with kayaks that may make it into cats one day, such as Vaccuum forming (thermoforming) with ABS, search on the net for Carbonlite, TCS, or Airalite for more info.

Gareth

Wouter,

A few corrections:



LS-They are still preferred in most ocean racing multihulls like the Open 60 tris. Bill designed his boats to sail with waves.




LS-Exactly, but shared lift is not only about balancing the boat with the spi. There is another claim: a smaller daggerboard further forward combined with a bigger rudder allow both foils to work more efficiently, ultimately reducing drag.




LS-Only the older boats I saw had straight tracks. I think curved tracks are being used today.




LS-High volume wingmasts may be older but Bill's idea was to SEAL them so that they can float. I think he was first in this.




LS-The SC 17 was designed to be sailed with half of the bow height under water for lift - remember it has no daggerboard.

Cheers,

I beg to differ about performance (not the manufacturer) boats being too weak and 'breaking too easy'. From a rental boat perspective, there are a lot more ropes, hardware, and sails to maintain on an I20 or Nacra6.0 whereas boats like the wave or Getaway don't have the high performance systems, are very simple, and cheaper to maintain. It's not really about breakage - more that there are fewer wear parts. We sailed an I20 offshore in the Tybee 500 and I promise you there's only one or two other catamarans I would feel safe on in that kind of mayhem - and none of them on that list are made from rotomolded plastic.

Wouter....you are one angry dude with WAY too much time on your hands....maybe you should sail more and write less. Might calm your nerves. (try sailing a SC - you might just like it).

>>>LS-They are still preferred in most ocean racing multihulls like the Open 60 tris. Bill designed his boats to sail with waves.


And you are implicetly saying that the other designers don't design boats to be sailed with waves ?


>>>LS-Exactly, but shared lift is not only about balancing the boat with the spi. There is another claim: a smaller daggerboard further forward combined with a bigger rudder allow both foils to work more efficiently, ultimately reducing drag.


The post clearly stated that shared lift was intended to counteract the spinnaker effects. I was commenting on that statement.

Apart from that Bill has agreed in writing that most efficient mode, drag bucket, can not been achieved when the rudder needs to provide significant lift. Not to mention to problems of having the rudder move in the wake of the daggeboard. There is more to this picture than just pump up the aspect ratio and Voila have significantly more efficient boards. But this is a whole different topic. I comment on the fact that other designers apparently have not seen the light as one particular designer. It stands to reason that this may have a different explaination than "other designers are stupid"


>>LS-Only the older boats I saw had straight tracks. I think curved tracks are being used today.


And who pioneered that, curved tracks I mean ?



>>LS-High volume wingmasts may be older but Bill's idea was to SEAL them so that they can float. I think he was first in this.

This seems like a very unprovable claim to me ; but if you have proof of this that do share it with us. I have a hard time believing that each cat before the SC-product line was doomed to be resued by a crane platform after each capsize.



>>LS-The SC 17 was designed to be sailed with half of the bow height under water for lift - remember it has no daggerboard.


Okay, when others do that then they have insufficient volume in the bows but when a ARC-17 does than it was fully intended. I do remember it has no daggerboard, that is why it has oversized rudders right ? Besides more then halve the bow is under. But never mind, they point yet again is that other designers have chosen other paths (solutions) and are just as effective in getting results if not more effect. I refer back to my comment woth regard to a superior design having a significant inferior handicap rating and needing that to come out on top.


Regards,

Wouter

Jake,

We have been doing market research recently and this is the opinion of the holiday company we spoke to, not my own. Their comments were specific to hull construction. They said "plastic hulls only".

They specifically mentioned wear from the boats being dragged up and down the beach all day. I have never owned a plastic boat, but my experience of my H16 is that it wears down pretty quick.

It would be interesting to hear what Mary or Rick have to say on this with their Wave experience.

All the best

Gareth

Wouter my friend...I will give you the benefit of the doubt about the bows of the ARC 17 being driven so far under water at the Aquarius web site. I specifically questioned Bill about that very thing on this open forum. His answer was that they purposely drove the bows under for the photo shoot to show the ARC 17's inherent resistance to pitch pole. I thought you had probably read that yourself.

As far as addressing your other comments...you know where I stand, and I know where you stand on these issues...lets just agree to disagree.

I was trying to give the original poster the information he requested...that is, identifying catamaran design problems and their possible solutions. Since Bill Roberts has spent pretty much his whole catamaran design career on this very topic, I thought it would be very informative to do a bit of research on Bill's design history.

I agree with you that there are many solutions to the same problem. What I was trying to convey is that from my perspective, Bill Roberts seem to have an uncanny ability to find solutions to design problem with logic while avoiding unnecessary complexity.

With all do respect, until you put in some time on one of his designs (with it properly set up) you may never fully appreciate his genius.

Regards,
Bob

Hi Boss,
I come from S Florida. When you talk about "problems" I am going to talk about serious problems, safety problems. A few sailors have lost their lives sailing beach cats here in Florida. In one case the boat sank due to no floatation, no foam in the laminate and no foam blocks in the hulls. Therefore all boats should be built with enough rigid flotation so that they are unsinkable, design requirement. In another case the boat pitchpoled due to a banana hull shape and low bow volume,very easy to pitchpole design, and a sailor drownded. Boats should be designed to be as pitchpole proof as possible, ie bows should be at least 1.5 times as tall as transoms, design requirement.
Safe Sailing,
Bill

I am saying that designers tend to round the foredeck as the waves and speed increase. The eliptical hulls are a bonus when sailing off the beach. The SC17 was designed to be a beach cat and it is a very good engineering solution for its design purpose.


I don't recall ANY boat - not only multihulls - with sealed masts before the Supercats, but naturally I don't know enough to prove it. Maybe someone else could help us clarify this.

Maybe the curved track was introduced by the America's Cup 12 meters (for the vang) or Star. I also recall seeing tracks curved in the other direction (up and down instead of fore and aft) in small monohulls a long time ago, but I think curved tracks may be older then me.

Cheers,
Luiz

careful Bill! lets not say something as an absolute about "bow depth" in the resistance to pitch pole! some young gun out there may take that and run with it and never incorporate the correct principles. As you know, (and have used in your own designs) any reistance to "pitch pole" has very little to do with the actual relationship between the bow and the stern! what does effect the "resistance to pitch pole" is the reduction to forward motion of the bow through the water when put under extra forward and downward pressure. As you have said your self, the easier that the bow will drive with little or no reduction in forward speed the less likely the hull is to "trip" (or pitch pole)
Darryl J Barrett

At one stage sealed masts were a requirement for ANY "off the beach cat" to be permitted to sail at any club here in South Australia. No sealed mast, illegal to race! that was through the 70's, and thank goodness the yachting authorities changed that in their wisdom to "all catamarans racing shall have the head of their masts sealed and the base of their mast vented (able to drain), which is infinitely safer than having the complete mast sealed. THERE IS NO SUCH THING as a mast that is "sealed" remaining sealed. The danger occurs when any part of the mast that has a fitting or a penetration through the wall of that mast, will EVENTUALLY NOT BE AIR AND/OR WATER TIGHT, the when/if that mast is submerged due to the increased water pressure (opposed to air pressure) it will fill with water very quickly, making it very difficult to raise, and when/if it is raised, the water pressure that pumped it full of water is gone and it remains full or drains only very slowly.
The safest mast is one that is vented at both head and at the base

Eliptical hulls, in my opinion, would not have offered us much advantage off the beach - such as in the following image.

Hi Gang,
I came to multihulls after sailing monohulls for 25 years and winning ten US Nationals in three different classes. In the 1960s and 70s I lived on a freshwater lake where most of the sailing was done in my area and I was sailing monohulls, dinghys, at that time. I saw the beach cats when they first came out. I watched them turn over and stick their masts in the bottom of the lake. I watched them turnover and blow the length of the lake with a guy and his girlfriend hanging on a rope trying to right the boat with no success. I watched them try to tack and get in irons on a windy day and have to back the jib and make the boat back around moving backwards to complete the tack. I watched them pitchpole when they would attempt to go fast on a reach. During this time period two persons drowned on the lake where I lived from pitchpoled boats. I have scar tissue from these times. I can still hear the sherriff's helicopter going up and down the lake waiting on the body to float to the surface and the rotor making that whak, whak, whak sound all day long.
When I began to think seriously about designing a beach cat, I promised myself that I would design a boat that would be as pitchpole resistant as possible and the boat would be rightable by the person sailing the boat and it would tack well enough to excersize classical tactics sailing to windward.
Evidently it took a monohull sailor to be concerned about these things, these boat design safety issues, and basic sailing characteristics. Even to this day no other production beach cat comes with a built in righting system.
Safe Sailing,
Bill

I don't know how many times I have to say it Bill, but you simply cannot say that. Isotopes come with a righting pole from the factory. Just because you haven't heard of them or seen them en-masse doesn't mean that they aren't there, therefore your marketing claim that your boats are the ONLY production catamarans that come with a built in righting system simply isn't true.

ONE of the only perhaps, but not the only.

I have never thought that the problem with "righting" a capsized cat was the problem of the cat, but more so with the experience and knowledge of the crew! IF proper, simple, accurate, training/instruction is imparted to a crew before they sail then righting SHOULD never be a problem! There have been courses conducted here for over 35 years on how to right a capsized cat. If a cat has a mast length over a certain length, it is impossible for the crew of that boat to right it with just their own weight, the leverage of the mast exerts just too much "load" for them to counteract, BUT if there is enough wind to "blow" them over, then there is enough wind to "sail" them up right, if they are aware of how to use it. When a crew knows that they are ditching or have ditched their only concern, in the first instance, is to get themselves onto the hull in the water ASAP. forget all else. They then can, by holding onto the dolphin striker or righting rope (and every cat should have a righting rope under pain of death if they dont - no pun intended-), lean their weight out board. By just leaning a little beyond the vertical they will keep the boat in the 90 degree position indefinately and stop a 180 degree roll over. Then if the crew, holding the righting rope and letting out appropriate amounts to maintain their "just off vertical" stance, moves forward on the hull as far as they can (preferably at least to the forestay bridle point, they will depress the bow of the cat deeper into the water, (as a consequence the transom will lift quite considerably). The hull will then have much more resistance to the sides way movement created by the wind at the bow and conversly the stern will have little resistance to that same force. The result is that the stern will move off wind and the bow will move up to, and point into the wind. With the hull pointing into the wind the air flow over the sail/s and mast (the mast of course being only partially in the water as the mast step position is in the centre of the boat ) will generate enough lift to pick up the mast and sails and the boat will come to rest in an upright position facing head to wind and relatively stationary.
This is the method that has been taught to probably thousands of cat sailors here over many years and as a result there has never been a catamaran, racing fatality, due to ditching in that time.

On the contetious subject of curved fore decks versus flat (or close to flat) it is important to remember that the curved deck with the same diameter as the distance across the flat will have an appreciable greater surface area. We conducted practical testing on just this subject during a feasability study for a "little America's Cup Challenge" in the early 70's and our findings were that an almost flat fore deck shed water more efficiently than an eliptical deck for the same bow profile, BUt the difference was moderate to the point that other considerations would far outweigh any prefference for flat or curved. It really is a non arguable point for or against!

Tacking a cat. I don't know if Bill has ever interested himself in cats other than those in his immediate line of site. One example that I wrote to him about was concerning his assumption that his were the first off the beach production cats to be made without a dolphin striker. When I mentioned the "Hydra" he confessed that he had never heard of it, which I found as a little lacking as they were a relatively popular British boat that achieved good export sales. and then there is the Australian Windrush 14 (I believe it goes by a different name in the USA), sold thousands since the mid 70's and still sells well, a centreboardless boat raced in large numbers, and it came out without a dolphin striker. So when he makes a sweeping statement in reference to catamarans that "could not tack" before his designs, I am forced to question his actual knowledge on the subject. Ever since the 60's there have been many classes of cats of all sizes racing in Australia that "tack as good as or better than mono hulls". There are several classes designed by the Cunninghams (perhaps you have heard of them, - they won several Little America's cup challenges -, that have been competing and still are competitive with almost any latter designs, then there is the Mosquito, the Cobra, the 18' Stingray,the Paper Tiger, the Arrow, the Arafura Cadet, The Dolphin, The Solo 16, and believe me these are but a few. These cats all sail very high to windward and tack up the beat on small knocks to advantage, they all race like thoroughbreds that defy any thing that Bill says to the contrary, and all of them were designed, built and had large fleets sailing every weekend at clubs all round Australia when Bill was still sailing in relatively slow monomarans

Oh and by the way, the Hobie 14 came out in its original form without a dolphin striker! Surely you saw that one Bill?

few of the cats had dolphinstrikers in the 60's.
shearwater, shark, and h14 are examples of strikerless.
to me the pitchpole-ability of h16 is a challenge more than a flaw. We sailed off the wind in a gail coming into hatteras during a worrell once on a h16 without pitching. There have been numerous h16 worlds heats held in winds above 25 kts. and the leaders don't tip over. also the raised trampoline is an asset in the sense that the sailors are up higher off the water, and are more comfortable sailing in rough seas.
on the subject of drowning: one word- lifejacket

i don't know about having a mast with holes top and btm.
Does anyone else think it's a good idea? Hobie14 in '68 was the first boat i sailed with a sealed mast. Granted some of them leaked, but they weren't meant to.
i was thinking of making a foam core composite mast. that certainly wouldn't fill with water if the proper foam was used. it seems i have the technology but not the time to develope it though.
cheers

Bill, Mr. Roberts,

When you say that no other cat comes with a righting system, you need to include all catamarans, including your own designs. Supercats do not come with a righting system.

Only a well prepared sailor can right the capsized catamaran. That is same sailor who created the circumstances leading to a capsize.

Catamarans are a vessel that are sailed with active cantilevered ballast. Active, moving around, and cantilevered, on a trapeze wire. Without the active ballast, the non-ballasted boats can not stay upright, beyond a certain wind speed.

Just as soon as the active ballast can not prevent capsize, the same active ballast (the sailors of the craft) must actively correct the capsize.

There is no system on any of the beachcats that can right the capsize without the active participation of the crew, the active ballast. That is the same person who caused the capsize.

There are many aides that a catamaran crew may use to right his capsized catamaran. Without the active participation of the crew, the capsized catamaran does not become un-capsized. (righted)

You, nor anyone, sells a catamaran that includes a crew who is able to right the capsized craft. Therefore, nobody, even you, has produced a catamaran that includes a means to right the capsized craft.

Furthermore.. I must express my objection to your email letter to me, five years ago, stating that every Supercat ever sold came with a one man righting system.

I have had correspondence with more than one Supercat sailors who were not able to right the Superheat 17 without some outside assistance, even after several repeated attempts.

My point here is that there is no beachcat (a cantilevered ballasted sailboat that does not use static, below the water surface, ballast weight) that can be righted without the active participation of some interested people. No tools will do the job if there is not present, the proper interested people.

Locally here in So. CA, we have a fleet of catamarans that sail to the Island of Catalina. The only cat sailor who has not been able to make the trip, owns a Superheat 19.

He has not been able to make the trip because he is not able to right his boat from a capsize unless he has a crew of three, aboard. THREE!

I would like to add to my comments that I really enjoy reading all of your knowledge filled posts. Also, I really love Supercats, especially the Supercat 17.

I, like so many here, look forward to your posts, intellignet comments, and wisdom. Thank you for all your past, as well as your present and future contributions.

GARY

Hi all,
Just my thoughts on this one :
Have to agree with Darryl, in that it takes proper technique to right a cat successfully.
Ask me, I know - I capsize often. 5 times in 2 races at Nationals, 3 times in 2 races at our solo champs, and once between races just for good measure.
No, I`m not a crap sailor, I`m just getting to grips with wild-thing downwind with the kite up, and if you`re sailing on the edge, you`re gonna go over once in a while.
The trick is in not worrying about it - IF you can right your boat. After 2 capsizes I was only 200m behind the fleet, and went completely turtle both times.
Here`s how to do it :

- Sail a boat you can right. What I mean is that I couldn`t right a Dart 18 on my own, I`m too light. This was one of the deciding factors in selling the boat & getting something that I can right on my own - you can`t sail something solo if you can`t right it solo.
- The moment you have to design paddles or lever-arms that you can get out on the end of to right the boat, you are sailing a boat that wasn`t designed for your weight, or was badly designed. Try standing on a pole 2ft away from your hull in 3-4m swell & strong wind. It`s hard enough staying with the boat, never mind fiddling with odd contraptions.
- Make sure your mast is sealed. If it is, it acts as positive bouyancy when turtle & actually contributes to the righting process. If it isn`t, it acts as ballast 30ft below your boat. Even if you get it back on it`s side, that`s as far as you`ll get it.

In my mind, you should only sail a boat solo if your weight exceeds the minimum weight required to right the boat.
And go out there & practice a LOT!! (like me )

Cheers
Steve

Firstly,

Why do people constantly change the title of discussion threads. The makes it very difficult to follow the thread via the 'posts in the last 24 Hrs' button at the bottom of the front screen.

Surely, if your comments are not relevant to the title you should start another thread. Thread titles are surely chosen by the originator of the thread to identify what they want to talk about.

Secondly regarding comments above about capsizing, pitch-poling etc.

If you are trying hard and pushing the envelope, you are going to swim every now and then.

If you are sailing a cat you will pitch-pole at some point what ever the design - unless it is TOTALLAY under canvassed or 'over length' for the canvas. Live with it.

If it is windy and you do not think you are up to sailing in the conditions, do not go out - Take responsibility for your own destiny. If you are not sufficiently skilled to sail the boat, buy a lower performance boat !

Hi Jake,
When I talk about eliptical hulls and safety and reduced pitchpole tendency, I am really only addressing the topside of the boat, the deck. Boats pitchpole at speed as you know. The boats in this picture are certainly not "at speed" and pitchpole is not a consideration. I don't know where you are coming from, Jake.
The second boat from the left is certainly getting its decks pounded and flat decks are certainly much higher drag than round decks from water crashing down on them moving in the vertical direction. The sailors on the third boat from the left are too far aft on their boat and this makes the boat stand on its transom as the wave passes. They are lucky they didn't get washed back to the beach.
Bill

Hi Darryl,
The important thing about the high crown foredeck vs a flat foredeck is the hull's drag coefficient when the foredeck is pushed underwater at high speed. This is also a much more important consideration when considering a boat for the general public vs a Little Americas Cup boat.The Little Americas Cup caliber sailors can handle any foredeck shape, no problem. The place where the foredeck shape and pitchpole characteristics become important is on a boat to be sold to the general public and to inexperienced sailors. Sailors where "to pitchpole" is a total surprise and they did not see it coming. People can be injured in this situation.
Bill

I agree the sailors on the boat were too far back - I am the one, not visible, under the crashing wave. However, we were in this position because the 6.0 to our left had rounded us up almost into irons and I was trying to fend off the boat to avoid damage. We did end up having to come back to the beach because we were eventually pushed head to wind.

The comment I made regarding eliptical hulls was in response to where someone made a claim that this shape aids in getting through the surf.

Luiz,

Selftacking jibs try early 1800 on traditional Dutch working sail boats. The originals that gave the US scow its name. But I bet it is even older than that. Any these used a curve steel bar over which a large ring could slide. On the ring was a large block that lead the jibsheet that came from the bow to the clew. In practice it is identical to the system now used on cats.

Wouter

>>I thought you had probably read that yourself.

No I hadn't.

>>As far as addressing your other comments...you know where I stand, and I know where you stand on these issues...lets just agree to disagree.

That is alright. I don't have a problem with Bill designs, I'm still looking to get a ride on that RC27 some day that is parked next to our club. No problem there. I'm only reacting to comments that go along the lines of "every other designer is misguided as the right solution is Bills design such and such."



>>I was trying to give the original poster the information he requested...that is, identifying catamaran design problems and their possible solutions. Since Bill Roberts has spent pretty much his whole catamaran design career on this very topic, I thought it would be very informative to do a bit of research on Bill's design history.


Well in that I agree. To a point I must add as sometimes Bill makes a claim that is not realistic. getting Massive leehelm under spi is one example. This may have been true in the past, I don't know, but it isn't now.


>>>With all do respect, until you put in some time on one of his designs (with it properly set up) you may never fully appreciate his genius.

I'm not coming into this unknowlegdable. I know of the attractions of a supercat and of its downsides.

Wouter

This thing about righting a cat illustrates that, from these postings, not enough people sailing on cats are fully aware of the proper techniques to right one that has ditched! As I described in my earlier post, ANY off the beach cat, (at least up to the size of a Tornado) can be righted quite quickly and safely by ONLY ONE PERSON, if the method that I described is followed! You do not "pull" a Cat up, you use the wind that has knocked you over to "sail" the cat into the upright position. It is efficient and leaves the crew in a much more physically competent way (they are not exhausted) than they were when they went into the water.
On the subject of "fully vented masts", at the head and at the base, sure when the head of the mast hits the water it will start to fill BUT, the surface of the water in the mast will always only remain at the level of the surface of the surrounding water, and water in water weighs nothing in relation to the crew trying to right it, the weight of water in the mast only effects the crew when it is contained and lifted free of the surounding water, and this means that the only weight that has to be supported by the crew is the actual weight of the mast. With the crew supporting the cat in the 90 degree position by "leaning" out on a righting rope they can easily support that weight, and the mast being in the position that the head is lower than the base (the base being above the water level as it is positioned in the centre of the cat which is half the beam of the cat above the water) allows, any water in the mast to flow out the head,IF THE BASE IS ALSO VENTED, so that there is no "suction" trying to impede that water flow. By having both head and base vented, the mast, in any attitude above water, will never hold water, and that can often be the main problem with "SEALED" masts. It is very rare that a so called "sealed" mast ever remains sealed for any length of time. The biggest problem is that every fitting and hole that is attached to or drilled into a mast, has to be sealed and by the nature of attaching two different types of material together, then trying to seal them with a third "compound" is fraught with the possibility (usually fact) that due to the different linear coefficient of expansion of different materials, that seal will not remain intact. once the integrety of the seal on any of the entrys to the mast are compromised, then, when the mast is submerged water will be forced into the mast under pressure, BUT when that pressure is removed (the mast comes out of the water) that water will either not drain from the mast or else it will drain very very slowly making the mast many times it's own weight.

Bill, our findings were that the difference between cambered fore decks and or flat fore decks, even "at speed", (as you say) and also when driven under water, were so miniscule to the point that there could not be ANY "noticable" difference to the performance of a cat using either.

Besides fellas, you are out on the water SAILING1 for gods sake! Of course you are going to go for a swim now and then, if you didn't, there wouldn't be much point in being out there any way? What next, do we encase all sailors on a water tight "suvival pod" so that we don't even get wet at all? and if we did, we would float away from the "boat" and be picked up by a rescue boat? all the time remaining "dry"? come on now. The difference between cats "pitchpoling" and "falling over sides ways" UNSAFELY" and dingy's being inherently safer, is a load of codswallup and myth! How many cat sailors have seen 9 to 12 year old "kids" out sailing/training in little "bath tubs" that regularly capsize , fill with water and have to be "assisted" by rescue crews? How many times have you seem classes of different dingys racing in heavy weather and the occasional boat being washed up on the shore because the crew could not right it and/or bail out the water? It seems to be a common occurence at all the clubs that I sail at that more rescues are made on dingies than on cats. At least the cats "float" when they ditch (unless punctured by collision) where as most of the dingies "swamp".

I don't agree on venting the mast on the top. I do agree on venting on the bottom. But I can sure underline the fact that the mono's are worse to right than a cat. My experience includes ; 49-er, laser 2000, laser 3000, laser 4000 and laser 5000. The laser 1 was very easy to right if you're quick enough to immediately step on the daggerboard in a capsize. I never capsized a laser 2. Besides all of these have "double vented" mast and I hate that with a passion. on the 49-er it takes ages for the water to run back out. If only they had sealed the top of the mast so that it would not fill with water to begin with.

Wouter

Hi Darryl,
Your experience is different from mine. In the early stages of development for the SC20, side by side pitchpole tests were run many times vs the Tornado. Both test teams were told to sail side by side on a broad reach in 20+ knots of wind and make no effort to prevent pitchpole, do not touch the sheets, just hold your couse. The Tornado pitchpoled much more frequently than the SC. Tests were also conducted with sailors switching boats. An interesting observation was made. The SC pitchpole was slower than the Tornado pitchpole. The SC's pitchpole rotation was slower and it took more distance travelled for the pitchpole to actually happen than the Tornado. The SC pitchpole was described as "mushey", happened more slowly, as described by the sailors. The Tornado pitchpole was "quick", it happened fast, in an instant. I think the difference in these characteristics is a reflection of the difference in hull drag once the foredeck is underwater and the pitchpole maneuver is underway.
Another benefit of the highly arched foredeck vs the flat sheet is that the arched shape is inherently stiffer than the flat deck and can carry a greater axial compression loads than the flat sheet. The foredeck of a catamaran hull is loaded primarily in axial compression.
More substantiation: WWII submarines operated at the interface between the air and the water, the surface of the water, during most of their operation. They ran along the surface of the water about half submerged. These boats spent most of their life "punching through waves/chop " just like our catanaran hulls. What hull cross section shape are they and especially what is the foredeck shape? Millions of dollars was spent to develope this optimum, low drag hull shape for this enviroment. What is this shape?? The ellipse, the egg!
Bill
PS Your sailing clubs in Australia were very very smart to teach catamaran sailors "how to right their boats", sailing lesson #1.

I have to add my 2 cents. Firstly, I'm 100% sure that I can't right my Tornado by myself (155 lbs), correct technique or not. On the one occasion we pitch poled, it was indeed VERY quick. Tons of wind, leaned forward to try to force down windward rudder that had popped up with main sheet cleated (big mistake), next instant, swimming, sore a$$ and boat upside down. Non-sealed mast, ALMOST righted using exact technique described (with crew total weight ~330 lbs), but not quite. Due to extreme conditions at the time, we had pre-arranged rescue boat, just for the record.
Never sailed a Supercat unfortunately.
Al

hi all,
I have a problem with calculating the center of effort. I understand that on a boat with a genoa, you work out the centre of the sail area for the mainsail (including the roach) + the genoa (foretriangle), then you use the average distance between the center of the genoa and the centre of the mainsail for the position to measure the distance to the waterline, but what if the cat had a small jib of an area of 2 m2. If you do what you did with the genoa (find the center of genoa) to the jib, the distance between the center of the mainsail to the centre of the jib is huge because the jib is so low down the mast and so small. on the FX-ONE you can have the jib as an option, but if you add or take away the jib won't it have a big affect on the center of effort? can anyone tell me how a professional cat designers work out the the center of effort with a cat with a small jib that sometimes would not be used?
regards
Tom

Hi Wouter,
I am going to respond to some of your comments one last time. I have a request for you. Do not ever use my name again on any of your posts. I do not think your intent is honorable and I do not want to be a part of it.
You know that my training is that of an engineer. Engineers know more than most other professions that there are many solutions to the same physical problem. Some are better than others but there are always many solutions to a given problem. That is part of the fun and pleasure of engineering. Your comment about me and "only one solution" is your invention. I have never said that.
>About pitchpole and H14s and 16s: I did my design work on the SC product line in the mid 1970s. At that time the H14 and H16 were the largest and fastest growing classes in the US. They were the chinning bar at that time and their sailing characteristics were the ones to improve on.
Inter 20 vs Tornado: Why do you think the position you bring forward exists? Let's look at shapes of bodies and drag coefficients. The last piece of the puzzle in the physics of pitchpole is a rapid rise in drag coefficient as the bow of the boat is pushed underwater and the water begins to impinge on the deck. If we look in an aerodynamics text book and find a table of drag coefficients of bodies of various shapes, we see that a flat plate has a very high drag coefficient, flow perpendicular to the surface of the plate. If we take that same flat plate and round/roll the edges with significant radius like the I20 shear line along the foredeck, there is a significant drop in the drag coeficient. This would reduce the I20's tendenct to pitchpole relative to a Tornado. When the deck becomes the bow of the boat, the shape that is parting the water, how draggy the deck is becomes important relative to pitchpole.
Elliptical hulls: When the best and finest F40 one design boat was designed it looked like a scaled up SC20. On the big cats and tris the elliptical hull shapes are the industry standard. In the beach cat business a newer boat cannot look like an older design for fear of being called a copy cat. No one would buy a new boat that looked like an older design even if the older design was superior in some aspects.
>Shared Lift: I first used the shared lift idea on the SC17. Half the lift to counter the side force from the sail was carried by the forward sections of the hull, deep Vee shape, and the other half carried by an oversize rudder. The aft end of the hull was round in cross section and can slide across the water sideways easily and this lets the boat tack much easier than other boardless beach cats. This 17ft boat developed a PN of 73 relative to the 16.5ft long H16 with a PN of 76. This performance improvement shows that the shared lift concept works. The SC17 also tacks much easier and faster than the H16 and is much much more pitchpole resistant.
>Shared lift and spinnakers: The European beach cats are slow to come to S Florida so I haven't sailed any of them. But looking at pictures of them sailing with spinnakers, I see a big difference from the spinnakers I sail with. I look at pictures of these European cats sailing double trap and I notice the leech of these spinnaker sails is just in front of the mast. These are very high aspect ratio spinnakers. The spinnakers I am use to are fairlead to the rear beam or transom. When sailing hot, the leech is only a couple of feet in front of the rear beam fairlead point. Now let's go back to the text book and aerodynamic theory. I see that the short footed, high aspect ratio spinnaker has a much higher lift to drag ratio than the long footed, full size, low aspect ratio spinnaker. This means that the resultant force from the high aspect ratio spinnaker will cross the platform, the boat, at a point, very near the CB trunks, that has little to no effect on helm. The full size spinnaker with its lower lift to drag ratio will generate a resultant force that crosses the boat in front of the CB trunks and this causes lee helm. The high aspect ratio smaller spinnaker will sail higher and faster than the low aspect ratio when sailing high in general. The larger low aspect ratio spinnaker will sail faster and deeper than the smaller high aspect ratio spinnaker when sailing low in general.
So, there you have it, Wouter. If you sail with these short footed, high aspect ratio spinnakers, you can live with the helm with the CB located in the classical position. If you go with a full size spinnaker, the boat requires the CB trunk to be located further forward to balance the helm.
Take a look at Alinghi. This boat has a second daggerboard half way between the main beam and the bow to trim the boat out when large headsails are used.
I'm tired of writing. Goodby Wouter,
Bill

Hello ****

>>Do not ever use my name again on any of your posts.


Okay, ****, I will not use your name anymore.

>>I do not think your intent is honorable and I do not want to be a part of it.

Think what ever you think and then try to stay true to the facts. One more note. if you think the anomymous attacks on you, like the one one the old forum are coming from me then I can garantee you that I will always sign my name to a post. Rest assured there is no comspiracy to "get a ****", these are all people who just want the truth to be told. Differences of opinion ? No problem. False claims ? You will get heat. And beleive me when I say that another other party will get that treatment under similar circumstances. Hell even I received some heat in the past, and often rightly so, when I stepped out of line.



>>Your comment about me and "only one solution" is your invention. I have never said that.

It is true you have never said, but you hint at in in all your other comments. They always go along the lines. "I already knew back in the 70's that .... and still boats today have .... . Of course all ARC and SC product do have .... ever since the first was produced as the only class / product .... etc"


>>>About pitchpole and H14s and 16s: I did my design work on the SC product line in the mid 1970s. At that time the H14 and H16 were the largest and fastest growing classes in the US. They were the chinning bar at that time and their sailing characteristics were the ones to improve on.


Perfectly understandable and that was never the thing I railed against. Point was and still is. That eliptical hulls have since then been replaced be rectangle hull with heavily rounded decks and after that inverted triangular shaped hull where the pointy side is towards the sky. The designed have moved on. I can assure you that an elliptical hulled A-cat or F18 will not be a big hit on today's cirquits. And there is alot of effort and rep going into these designs currently.


>>>Inter 20 vs Tornado: Why do you think the position you bring forward exists?

Simply because the I-20 can get away with a fat flat deck because of teh rounded corners (as you also say) and because the excess volume keeps the bows up. No matter how you put it I-20 hull are not ellipical in shape and do have very good dive resistance. It was an example of a different solution.


>>Elliptical hulls: When the best and finest F40 one design boat was designed it looked like a scaled up SC20.

When was the last F40 designed ? And I know that making a good small airplane goes along different line than a good major jetliner. Large differences in overall size do often alter design problems enough to warrant different solution or tip the balance into a different direction. All the big cats (club med etc) have a 3rd beam in front of the mainbeam. It will be clear enough that this is not a particular smart thing to do on beach cats that are shorter 20 ft.


>>On the big cats and tris the elliptical hull shapes are the industry standard. Even there we see alot of fine entry bows that transform into a high rectangle with rounded corner tehn transition into an ellips or rounded box section and then end in rounded triangular or semicircular sterns. In one hull we go from a flat tall rectangle to a triangle or semicicle via box, rounded rectangle or ellips midsections. We do we want to call these elliptical when they incorporate almost all sections know to man and different station along the date line ?


>>>Shared Lift: I first used the shared lift idea on the SC17. Half the lift to counter the side force from the sail was carried by the forward sections of the hull, deep Vee shape, and the other half carried by an oversize rudder.

There is simply no catamaran that doesn't use shared lift in this sense. With each design part of the resisting sideforce is provided by the hull, sometimes a part is provided by daggers as well and the residue is taking up by the rudder.


>>This performance improvement shows that the shared lift concept works. The SC17 also tacks much easier and faster than the H16 and is much much more pitchpole resistant.


So, all boats designed after 1980 tack better than a Hobie 16 ? And almost none use the same setup as your 17 footer. Big win.


>>>Shared lift and spinnakers: The European beach cats are slow to come to S Florida so I haven't sailed any of them.

Okay , that is fully exceptable and will never cause me to post sceptical comments. Honestly.

But of course even with this fact, "I haven't sailed any of them", you tend to give alot of advice regarding the right construction of these systems to inquiring posters. A favorite claim of you was and is that spinnakers introduce alot of leehelm on cats. Clearly you can't know that when you haven't sailed any of the post 1994 spinnakers; by your own admission. If you don't know then don't comment on it with such displayed certainty.



>>>But looking at pictures of them sailing with spinnakers, I see a big difference from the spinnakers I sail with.

By inquiring posters always ask advice regarding THESE NEW STYLE EUROPEAN SPINNAKERS. I actually think they more Australian in origin but that is a side issue. The gennakers were first developped on the large Aussie skiffs and then jump ship to the F18 class and F20 classes. So you sail with different spinnakers, fine, I have no problem with that. However all modern cat sailors, I-17, I-20 , F18, F18HT, Tornado's, F16's, any new aftermarket spi for any sailor upgrading his cat out of the range H20 to Prindle 15 is getting the new cut spinnakers. Clearly it stands to reason that your experience with old style spis (who did really behave differently) is not really helpful in these situations.


>>>I look at pictures of these European cats sailing double trap and I notice the leech of these spinnaker sails is just in front of the mast. These are very high aspect ratio spinnakers.


They are indeed, and the speeds they are operated in are also alot higher. Most modern spi boats currently sail with an apparent wind at about 80 degrees from the centreline or even less. They are very far apart from true spinnakers; hence the name gennakers.



>>The spinnakers I am use to are fairlead to the rear beam or transom. When sailing hot, the leech is only a couple of feet in front of the rear beam fairlead point. Now let's go back to the text book and aerodynamic theory. I see that the short footed, high aspect ratio spinnaker has a much higher lift to drag ratio than the long footed, full size, low aspect ratio spinnaker. This means that the resultant force from the high aspect ratio spinnaker will cross the platform, the boat, at a point, very near the CB trunks, that has little to no effect on helm. The full size spinnaker with its lower lift to drag ratio will generate a resultant force that crosses the boat in front of the CB trunks and this causes lee helm.


And I think you say a true thing here, it seems to explain what real life sailing shows us. See I have no problem agreeing or honouring your plausible statements when I see them.


>>>The high aspect ratio smaller spinnaker will sail higher and faster than the low aspect ratio when sailing high in general. The larger low aspect ratio spinnaker will sail faster and deeper than the smaller high aspect ratio spinnaker when sailing low in general.


Definately true. The breakthrough in both skiffs and cats was that propulsion using lift and apparent wind allows these crafts to move around the very physical limit of max speed of a mormal spi as this sail try to sail itself in a windless hole it has created itself. Of course this is the very reason we don't see these true spinnakers on high performance sailboats anymore. Actually teh skiff designers found that increases in downwind speed currently have to be sought in reducing the operating angle of attack of the whole rig. Something that was totally weird some 15 years ago. The new line of designs are approaching minimum angle of attack limits. Meaning the luff of the sails start flapping before the craft has reached its top speed on a given course. This is the main reason why the spis are being cut flatter and flatter.


>>So, there you have it, Wouter. If you sail with these short footed, high aspect ratio spinnakers, you can live with the helm with the CB located in the classical position. If you go with a full size spinnaker, the boat requires the CB trunk to be located further forward to balance the helm.

And you are fully correct in this. And as we cat sailors do now exclusively sail with "these short footed, high aspect ratio spinnakers" there is not any reall leehelm problem that needs solving by a daggerboard well in front of the meainbeam. Of course such a setup may have other convincing advantages by that is another discussion.


>>Take a look at Alinghi. This boat has a second daggerboard half way between the main beam and the bow to trim the boat out when large headsails are used.


I think these boards have a different function as well and that that is part of the reason why they are so far forward.


>>I'm tired of writing. Goodby Wouter,


Goodbye ****

Wouter

I think you have explained why our results were different Bill. Yes in the example that you give ie SC versus Tornado, the differences would, I think, (without actually doing the tests) be as you say, but in my opinion, that is not the correct way of conducting an accurate test for "camber deck as compared to flat, or very near flat" To "compare" two different hull forms is just that, a comparison between those two hull forms,on two entirely different characteristic hulls, and the result that you get is a "comparison" between the entire differences of their hull form, not specifically the fore decks. To test whether camber is more efficient to flat, in this instant, the same identical forms must be used in the same controlled conditions with the only difference being the area that is being tested ie the fore decks. As to the anecdotal example of submarines, I think that if you were to research the evolution of the submarine, you will find that the curves over the complete vessel resulted from the need to have the greatest reistance to underwater pressure, and how the submarine travelled at the surface was only of minor secondary consideration. Besides the vast majority of submarines produced through out the second world war all had flat decks. It was only their inner "pressure hull that was curved.

The only thing that I can say AL, is that yes you are right! There are water conditions where, no matter what you do it is very difficult - almost impossible to right any cat (and/or dingy) but those are exceptional conditions where the actual water conditions are the problem, not the righting technique.
In winds up to 18 knots odd (true wind speed) I have personally righted a Tornadoe on several different occasions, and on others I have been unable to right a 14' cat, no matter what I did in winds that came up to over 30 knots with very (very) steep breaking head waves very close together. Every time I looked like getting some where a wave would break and sweep the cat around and slam me down and I had to start again. I don't say that any method is fool froof, but there are methods better than others and if people are going to sail then they should at least "have a fighting chance" of survival.

Besides Bill and Wouter you guys have to remember that "there are thousands of ways to skin a cat" (pardon the pun) and no one, to my knowledge has, as yet, found the best way! It seems that semantics and minor differences create the greatest amount of "heated" argument when most of it won't amount to a "hill of beans" in 50 years time. Perhaps we should all try a little to keep it in perspective. If not lets all move to the middle east to live and continue the arguments. (At least there the one with the biggest gun could have the best argument?)

Bill, on any forum like this one, if you ever try to "explain" principles of Hydrodynamics, aerodynamics, boundary layers, drag coefficients etc, you are going to get yourself into arguments. Most sailors seem, in my opinion, to want "instant" coroboration to their "assumptions" often made by "seat of the pants" so if you try to give any "technical" explaination, your an open target. If you just give them a "reference" where they can read the information themselves, they are satisfied, or at least they won't admit other than satisfaction, as that would show that they couldn't be bothered to look up the reference or that if they did they couldn't understand it or they read it and were enlightened. Which ever applies it has kept you out of the fireing line. Keep it simply, ie some one asks "whats your new design like" answer "real good mate" "no, WHATS it REALLY like" answer "realy, REALY good mate" "OH YOU MEAN that it's GOOD, well that's what I wanted to know!".

Gentlemen,

There is a post elsewhere in this thread that belongs here:



My own two cents come in the form of an old (probably true) story. It's about a great rabi who became crazy and all his disciples left him until only the first disciple - who also was an important rabi - remained. When people asked the disciple why he kept studying with a crazy man, he said that the master might be crazy, but HE was not: "I can tell when the genius is speaking and when the crazy man is, and learn from the genius only".

A wise man can learn from everybody, even from the crazy or stupid. It is up to each of us to separate the good and the bad and react positively to the good only.

It is good to learn from all of you, even when you are all mad , so please keep feeding us with bits of your knowledge.

Take care,

Put in another context.
It's more interesting and makes better reading when parties disagree than if everyone, boringly agreed???

Bill I don't think that anyone has any problems with the "actual principles" that you expound, but I feel that there is an area of doubt in some of the ways that you attempt to explain YOUR application of those principles to hull form.
From all the postings that I have read of yours, I can find nothing wrong with your design criteria, but at times I find debatable the absolutes that it appears that you apply to them. In my opinion you do tend to leave yourself open to disagreement by apparently "shutting the door" to other variants. Nothing at all wrong with that. It takes a large degree of "single mindesness" to be able to even sit down and design a boat, carry it through to fulfillment and fend off the knockers that will always hover, hoping that they can drag it down to a common level. If there wasn't disagreement it would be a boring old place to live in.

BUT how did the second rabbi know that the first one was crazy and HE was sane?? what if the first was sane and he was crazy? OR what if they were both crazy? What if everyone else was crazy and the first was sane and the second one knew it but was catering to the masses? what if - - - - - adfinitum?????? Lots of questions, who knows the answers, OR only THINKS they know???????

He was sane enough to teach us what worked for him, so...



Then we are learning from a crazy man's tale and this in itself is proof of his point - crazy or not.



Then we are learning from a crazy man who learned from another crazy man. This proves the same point.



Then we are learning from a madman teaching madmen what a wise man taught him. This still proves the same point.



Now, what if the second rabi said he could learn from the first one when it was actually impossible and all he wanted was to keep the status quo (home, money, prestige, etc.)?

Then he is even wiser and smarter then we thought - and if a wise and smart man teaches us to learn from everybody, we'd rather follow his advice.

You are right, we could go on forever and still remain in the same place. Have you designed or built any boat with hydrofoils?

Cheers,

Tom a simple, suitable means to most of your needs for ascertaining the combined CE of your sail plan would be to scale out the boat with the mast, sails etc in their relative position, geometrically draw the C of E of each sail, scale the point relative to the combination of all the sails to find the point at which the Cof E of all of them acts then project that down through the hull. For the purpose that it appears that you need it should be accurate enough to assume that all three sails are flat thereby not needing to go into more complicated calculations allowing for the differences in their shape and "drive" positions etc. You can do this with only one sail or with two or with all three, then you can see a good comparison with how the centre of effort of the different combionations will effect the balance.

Hydrofoils? yes but only in half scale models for testing, I decided many years ago that true hydrofoils were fraught with a few very difficult excentricities that made for design difficulties that are still as pertinent today as when they were avidly experimenting with in the 1950's. There have been some very great innovations in recent years, but the draw backs that are present still leave a lot to be desired for a craft to "put out" for general sailing purposes. To put it in another way, the con's, as far as I am concerned, still outway the pro's
I have designed a variation on the "foil borne" sailing craft though, that has passed all testing with flying colors, BUT, although we have sailed a full scale 4.3 test version of it, it has the appearance and out right performance that I feel would completely inhibit it from proving a commercial success at this point in time, and I am afraid that I am a little past the stage in life of producing some thing just to "prove" a point and satisfy my own ego. Still who knows, if interest moves in that direction we may just produce them.
As opposed to "sailing craft" or "hydrofoils" I call this an "Aqu Glider".

Ehhh. One has to remember that the situation is a 3D situation and not merely a 2D one.

Example. In 2D nearly all monohulls will appear to have lee helm when going straight downwind. However as good as all have weatherhelm at this point. This is because the boom is so far out that de CE of the main is so far to the side of the point of drag that the net result is weatherhelm. It is entirely possible to have a boat that can move from weatherhelm to leehelm and back to weatherhelm when going from a beat to straight downwind sailing. In short the 3D pictures is very important and with monohulls even the heel of the boat can give rise to great differences. Another example. A given monohull can have leehelm on a straight downwind run in light air (hardly any heeling) and transition to weatherhelm in a guts (large heeling) when still sailing on the same course.

I agree that Darryls methode is a good grafical methode for finding the CE for the situation where all the sail are sheeting as good as parallel to the centreline but be very careful when extrapolating these result to other course that may have the sails sheeted significantly differently. Of course the spinnaker issue is one of such apparently contradictionary situations. Where the grafical methode suggest alot of lee helm being introduce when in reality this is not really the case.

Regards,

Wouter

Actually the 3D situation on sailboats is a very interesting one.

Even far ago designers knew about this issue/problem. The large schooners and such of two centuries ago were designed to be sailing with a minimal heel. The desired amount of weatherhelm was designed into the craft at that heel. This left the problematic situation where in very light winds (almost no heel) the boat would have leehelm on all courses including going to weather. To combat this the top sails were invented. These are the relatively small sail all the way at the top of the mast. Often tensioned between the mast top and the top Ra (English translation ?). These are not at all intented to provide propulsion but to induce heel so that the craft would return to its design sailing behaviour. Of course any extra propulsion provided would be welcomed by the main goal was extra heel and this was the main criteria of wether to deploy these sails or not.

Also Breaching on a mono hull can only be fully explained by a 3D situation. And as a matter of fact it is a desired characteristic. It is used on mono's as an extra safety mode.

You see how important 3D considerations can be ?

Wouter

lets not get too technical Wouter, if it is kept as a simple two dimensional graphic, it will suit for the purpose of illustration for a "visual" calculation that will show a reasonable representation of where his centre of effort is that will in turn help him to determine it's rtelationship to the centre of lateral resistance of his hulls and from that the understanding of how adjustments can be made to balance the two on different points of sail by all sorts of "set ups" ie mast rake, crew position for different points of sail, cemtreboards raised or lowered for different points of sail and different combinations of sails, etc, etc, and the use of his hulls "shared resistance with his centre boards and rudders, to leeward drift (or shared lift -as Bill may say-)" Or as I tend to say, "keep the leeward hull deep to counter any extravegant lee (or windward) drift, and the windward hull just free of the water.

Greetings,

So what are the practical solutions to the same problems. In your opinion, which is the easiest boardless catamaran to tack? Which boat is the easiest to right after capsizing? Which boat is the most pitch-pole resistant? Which boat is the smoothest sailing or hopping resistant? Which boat is the dryest for the sailor?

SC17, Nacra 5.7/570, G-Cat 5.7 and Prindle 18

Regards,

S. Knapp