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