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Re: What is the ideal beach cat design [Re: Tornado_ALIVE] #23187
08/19/03 09:02 AM
08/19/03 09:02 AM
Joined: Nov 2001
Posts: 351
Dallas, Texas
thom Offline
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Stephen- go to my web page in the photo section and you will find some pics of my ARC22 on the trailer. I don't have any of the boat on the water uploaded as yet.

thom

-- Have You Seen This? --
Re: What is the ideal beach cat design [Re: Jake] #23188
08/19/03 10:00 AM
08/19/03 10:00 AM
Joined: Aug 2003
Posts: 284
S. Florida
BRoberts Offline
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Hi Jake,
The first thing I did to our 'phantom boat' was to power it up a little as Carl suggested to 300 sqft of sail area. Then I increased the crew righting lever arm until the boat had the same 'total righting moment to sail area ratio' as the Tornado Sport. This rational leads to a boat that has a higher power/sail area to weight ratio than the TS and the same righting moment to sail area ratio as the TS. This leads to a boat that is faster than the TS.
My whole point was to show that this design thing is a difficult task and you can't just grab a few features and throw them together and have a faster boat guaranteed. You have to do Performance Analysis on paper before you fly off and build a boat that misses your goals.
Your analysis, Jake, gets your boat up to the same righting moment as the TS but it is a heavy boat so it will be slower in all conditions because it is down in power/sail area to weight ratio relative to the TS. Your boat has 264sqft of sail area according to a web site. To have the same righting moment to sail area ratio as the TS, your boat needs a total righting moment of 6415 ftlbs. This leads to 11ft wide rails or a 22ft wide boat with nobody on the trapeze. Get out on the wire and the boat is 28ft wide. It happens fast doesn't it and it is still slower than a Tornado Sport.
Keep this in mind: If the goal is to build a faster boat than some objective, the overall performance goal will only be met when the basic design parameters of the new design exceed the competition. Building a new design with equal performance design parameters to the competition will always fail to be successful. At best the new boat will be equal to the old boat and who wants to build a new product that is the same performance as an old product. For a new design to be faster than an old design, the new design must EXCEED the old design in every performance related design parameter.
Good Sailing,
Bill

Re: What is the ideal beach cat design [Re: thom] #23189
08/19/03 10:07 AM
08/19/03 10:07 AM
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S. Florida
BRoberts Offline
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Thom,
You know where to get anything you want for your ARC products, FROM THE FACTORY.
Bill

Re: What is the ideal beach cat design [Re: BRoberts] #23190
08/19/03 10:56 AM
08/19/03 10:56 AM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
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Thanks for your reply Bill,

I think we are comparing apples to oranges by trying to get the same sail area to righting moment ratio between a 10' wide, 251 sq ft Tornado and a nut busting 8.5' wide boat with Carl's 300 sq ft worth of sails. I'm not trying to defend Carl's desire for monster sail area but I am trying to defend the addition of racks to the 6.0NA to achieve considerable more righting moment with minimal weight gain. OK, my 6.0 is a good deal heavier than the Tornado and even with Racks, I'm not claiming it will be just as fast, but with my current upwind sail area (which is actually greater), I can achieve the same sail area to righting moment (same 320lbs of crew weight; although this is pretty light for a 6.0) ratio double trapped on a 2.5' rack. Add Carl's monster sail area and yeah, our boat + racks would have to be 18.9' wide.


Jake Kohl
Re: -beach cat design -and major events [Re: Jake] #23191
08/19/03 01:06 PM
08/19/03 01:06 PM
Joined: Jul 2001
Posts: 800
MI
sail6000 Offline OP
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MI
Hi Jake & Bill ,

Great to have interesting exchange of views on ideal design which may be so many different ideal concepts based on intent of use.
Some include {cruising -racing } --then the practical limitations -{budget constrainsts and size limitation ,-14 footer or 120 ft Playstation },-, ,
{geographic location},--need to trailer,-- or lake and protected harbor type sailing to ocean or Great Lakes type sailing in seas and surf , and{ sailing experience } -racing background ,-type of racing -races in a large class or smaller rated groups ,-type of boat sailed ,-{all relate their veiws based on existing experiences }.

Think your in agreement on the wing aspect ,-as Bill noted the addition of 5 ft wings on the 30 design .

To revisit the last comment in the original post ---
future racing and events --
The 30 seems like the ideal craft or at least one class
{maybe another at 20 with wings}-for it when another ProSail type series {raced on F-40S and H-21S }or similar interesting major distance race event capable of drawing in a major sports marketing entrapenure and ESPN or TV time ,-
{peole will watch putting for an hour --amazing }
The sport needs this type of exposure as one aspect towards its renewal and increased interest in it .

It was a great experience to race in Prosail and the Ultimate Yacht Race series on H-21s BACK IN 88 as seen on ESPN and NBC Sports .
They picked the breeziest venues and some of the major sailing centers around the country ,-NewPort R I -and Mystic Con .-Miami ,-Great Lakes area ,on St Clair -Corpus Cristy Tex ,-San Francisco ,-etc ,--

Another sure way to create international interest would be the always interesting human drama aspect of distance racing on high speed cats and the course raced ,-The 1000 mile races and the Tybee 500 draw this and international interest , With larger potentially faster craft like 30s the course raced should become larger ,-Racing across the Atlantic has always been a great one ,-earlier OSTAR races and other examples indicate this as well as around the globe races ,-which seem too extreme to most sailing though feilds of "growlers" -ice chuncks in the S-Ocean ,-but across the Atlantic , seems very possible and ecomonically feasable on the 30s . --The 120 ftrs too expensive or evan 60 tris --often too fragile and expensive ,--the 30s may be the ideal craft .

Maybe it is just my very excellent sailing teamate in the Tybee 500 this year ,Gale ,- http://www.galebrowning.com/
who is targeting around alone in 06---
that has me thinking in these terms ,but think racing F-30s across the Atlantic in internation competition with live camera aboard each would be a fasinating film all sailors and all people would enjoy seeing , something very marketable particularly in this sports crazed extreme reality T V type trend currently .-
It would draw in all types of racing enthusiasts from numerous sailing classes around the globe.

The sponsor idealy would provide 20 to 25 boats and allow entries of teams of 3 plus an alternate in teams from around the globe ,and provide all aspects of event organization ,-- needed modification for an Atlantic race like reef systems ,-storage of water and supplies would be needed ,and a dry safe in hull sleeping area --assume this could be accomplished along with other design aspects geared towards this more extreme event ,along with standards of EPIRBS -phones GPS ,-flares etc that have become the norm in the 1000 mile races ,-teams would outfit and supply themselves as the major team expence along with transportation of personel .-

The transformation of what will be called -THE aMERICAS cUP ON cATS -on HT 18s will be interesting ,-but think something bigger is needed to capture the imagination of the general public .

Both sides of {the big pond } would get very interested in this type of event ,-

For now we have to settle for the 500 or 1000 mile coastal versions ,-but think we will see this in the future .
Be ready Bill and Tom ,--and potential Sailing teams out there .-
Always good to place interesting ideas and concepts out there ,-for ideal design and events -food for thought

Carl .


Re: What is the ideal beach cat design [Re: BRoberts] #23192
08/19/03 01:31 PM
08/19/03 01:31 PM
Joined: Nov 2001
Posts: 351
Dallas, Texas
thom Offline
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Haberman is going to build some battens for both my F25c and FMS 20. I sent him the info on the F25c last month. I'm also going to consult him about a stern hung rudder as well.

thom

Re: -beach cat design -and major events [Re: sail6000] #23193
08/19/03 03:08 PM
08/19/03 03:08 PM
Joined: Apr 2002
Posts: 591
Bradenton, FL
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I'm sorry, but I fail to see how sponsor-provided boats sailing across the Atlantic is going to gain the interest of the non-sailing public.

Even golfers take their clubs home with them.

It still seems like a very expensive race you're dreaming about.

I think you'd get more people to watch 10 Tornado teams racing across the Atlantic. Slightly less extreme, would be 10 Reynolds 21-style boats. Call them maximum beach-cats or minimum cruisers if you will. An added flair would be if the teams each built their own boats. You'd have stitch-and-glue plywood designs going up against strip-planked cedar or foam-sandwich boats. Kinda like a poor-mans Paris-Dakaar race across open ocean.


G-Cat 5.7M #583 (sail # currently 100) in Bradenton, FL Hobie 14T
Re: What is the ideal beach cat design [Re: Jake] #23194
08/19/03 07:29 PM
08/19/03 07:29 PM
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S. Florida
BRoberts Offline
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Hi Jake,
Racks added to a N6.0 would definately make the boat faster than it presently is in medium and heavy weather and smaller people could sail the boat better/faster in stronger winds. These are all +++++s.
There was a time when boats were 8ft wide with double trap and sail areas were around 210 sqft to 220 sqft. Now we have added 0.5ft or 6% to the width of beach cats and the sail areas are up 20% to 30%. What's going on? Where's the balance? Ans: The factories have added sail area to their new products to make them faster than other new products. So what has happened is the new products are faster in light winds but they are slower when the wind blows and they now favor people of greater weight.
Notice the jam-up of Portsmouth Numbers around 60 + or - 1. There are boats of different sail plans and hull shapes and board and rudder shapes and rigging arrangements but they all run to the same PN which says these boats are the same performance level within 1 PN point. What is causing that???
These boats have one basic design measurement in common, the 8.5ft width. Boat width sets maximum righting moment. Max righting moment sets maximum sail thrust and maximum sail thrust sets max boat speed. So you give all these 20x8.5ft wide boats the same max sail thrust and they all go the same speed within 1 PN point.
Look at the CFR20, 20x8.5ft. A 275 pound boat with 287 sqft of sail on a 34ft mast and. Everybody thought this boat was going to be a rocketship being 150 pounds lighter than other 20x8.5ft wide boats plus it has a big unirig sail plan which is supposed to be more efficient. What is its PN? Guess what, 59.4. I point this out only to show how basic to performance 'boat width'is. Boat width is king when it comes to performance for boats of the same length. As long as we stick with this 8.5ft wide thing, we are going to be stuck with boats with a PN of 60. You can spend thousands of dollars and have all carbon everything and take a hundred plus pounds off the weight of your boat and your PN is still going to be 60 as long as the boat is 8.5ft wide. When are we going to break the barrier? When are we going to step into the world of really fast boats that the average size person can sail to its maximun in strong winds?
Bill

Re: What is the ideal beach cat design [Re: BRoberts] #23195
08/19/03 07:45 PM
08/19/03 07:45 PM
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S. Florida
BRoberts Offline
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Hi Jake,
I made an arithmetic mistake in my previous post. For the N6.0 to have the same righting moment to sail area ratio as the TS, the hicking lever arm for the double trap 320 pounds of crew is 11ft. This doesn't make the boat 22ft wide. It only makes the boat 13.5ft wide and add the people out on the trap and the boat requires 19.5ft of room/width on the starting line.
Bill

Re: What is the ideal beach cat design [Re: BRoberts] #23196
08/19/03 09:36 PM
08/19/03 09:36 PM
Joined: Jul 2002
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Yardley PA
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Bill and Jake...Very interesting discussion. First I should say that I am an Architect which means I know enough engineering to be dangerous. My question is this, Increasing the righting moment only increases the max wind speed that can be accepted before depowering is required. But there will be a range of wind speed where a narrower boat with wings will fly a hull and the wider boat will not. In this range isn't the narrower boat faster all other things being equal. Sometimes a lower righting moment is desireable...Dan

Re: What is the ideal beach cat design [Re: BRoberts] #23197
08/19/03 10:18 PM
08/19/03 10:18 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
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Thanks for the discussion Bill!...I can go to bed now as for I have 'learnt' my thing for the day. Seriously - that was fun. Now I just need a tubing bender for that 2" OD aluminum tubing and to figure out a way to get out on that 2.5' rack without killing myself.


Jake Kohl
Re: What is the ideal beach cat design [Re: Jake] #23198
08/19/03 10:36 PM
08/19/03 10:36 PM
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Its not all that hard...

Ok, maybe it is, took me a couple tries to get out on my wing without inadvertently going off course

Re: What is the ideal beach cat design [Re: DanWard] #23199
08/20/03 09:44 AM
08/20/03 09:44 AM
Joined: Aug 2003
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S. Florida
BRoberts Offline
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Dan,
There is no rule that says the skipper and crew must always sit on the windward hull. To go fast the skipper and crew, the balast, should sit where ever is necessary to allow the boat to 'fly a hull'. There have been comments on this forum about A cat sailors sitting in the middle of the tramp and 'flying a hull downwind'. Look at some of the righting moment numbers in this thread and you will see that the people on the boat are the major contributors to total righting moment. To go fast the sailors should always place their weight so as to allow the boat to just barely 'fly a hull'.
Good Sailing,
Bill

Physics will not be ignored... [Re: BRoberts] #23200
08/20/03 12:23 PM
08/20/03 12:23 PM
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Ft. Pierce, Fl. USA
Seeker Offline
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Very interesting discussion…it is amazing how Mr. Roberts can explain over and over again how things work in the real engineering world, only to have the catamaran community hide it’s head in the sand and ignore the reality of Physics.

Seems, everyone wants a faster boat…BUT…they artificially paint themselves into a corner with self imposed limitations on Length, Width, Weight, and Sail area, Mast height…etc… You know one of the definitions of insanity is “one who wants to do things the same way they have always done them, but achieve different results.

I am starting to come to the conclusion that “racing rules” have done more to harm the development of boat design, be it power or sail…mono hull or multi hull…than any other factor. To get a very good handle on this topic read “Seaworthiness, The Forgotten Factor” By C.A. Marchaj. It talks about how racing rules have driven ocean going Mono Hulls farther and farther away from seaworthy designs, as designers have gone to extremes to “cheat” the rules…he speaks of how many of today’s mono hull designs have little to do with what is “best” at sea…and everything to do with twisting design perimeters, forcing them to design in a self imposed box. All for the elusive carrot of ‘fair racing”. Which for all practical purposes will never be achieved 100% …

Some where along the line things went way off track…no longer is it about designing and building the best boat regardless of limitations. “Trailing width” has become one of the “all powerful” limiting factors of Catamaran design. I find it amazing that everyone pretty much acknowledges this fact, and accepts it without protest. Instead of limiting “on the water” performance because of trailering…why not attack the real problem…the transportation of the boat to the water.

It appears that SC/ARC has made great strides in that direction, but the majority seem easily defeated by this problem… so quick to “roll over and play dead”. We sent a man to the moon, are you going to tell me we can’t come up with a better solution in transporting a 400 lb. boat?

I find it very sad that the designers of true innovation and superior products (like Mr. Roberts) who strive for the “best” within practical limits…who refuse to be put in a box…find limited commercial success, while those who are more adept at marketing than design/engineering, fair much better in the economic arena.

I will venture to say that until the catamaran community is willing to shake off its self imposed chains of “racing design rules” (which I don’t see happening), it will be artificially frozen in the doldrums of mediocrity.

The 38-year-old Tornado Catamaran’s current level of performance when compared to the “latest and greatest” drives this point home with undeniable clarity.

In our new “ politically correct” society”… we have come to expect that things will conform to “our reality”. Unfortunately…or dare I say fortunately…physics has some frustrating lessons for those that choose to ignore it's Laws...

Bob

Re: Physics will not be ignored... [Re: Seeker] #23201
08/20/03 12:46 PM
08/20/03 12:46 PM
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seeker:

You make several good points, however, I'd just like to point out that I would, in an instant without hesitation trade my H17 up for a tornado in any condition, if it was narrow enough to safely trailer around. You have to factor in transportation into your sailing experience, if your boat doesn't even make it to the water, theres little point in trying to argue about its hydrodynamics.

Re: Physics will not be ignored... [Re: MauganN20] #23202
08/20/03 02:50 PM
08/20/03 02:50 PM
Joined: Aug 2003
Posts: 284
S. Florida
BRoberts Offline
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Hello Maugan17,
Most wide boats can be taken apart by removing 8 bolts, 2 at each end of each beam. Then the hulls and beams rolled up in the tramp are loaded onto a trailer with the hulls sitting side by side. The sails and rudders go in the sail box. It is no big deal.
In 1978 I came out with a boat 20ft x 12ft, the SC20. The beams telescoped from 8ft wide out to 12ft. The tramp stayed on the hulls and beams. The rudders stayed on the hulls. It took 20 minutes to go from 8ft wide to 12ft wide with mast up. The boat had a PN of 60 without spinnaker.
It was a great family boat and it was also the fastest production beach cat ever built. Have you ever heard of this boat?
Bill

Agreed [Re: Seeker] #23203
08/20/03 03:50 PM
08/20/03 03:50 PM
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Asuncion, Paraguay
Luiz Offline
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If trailing width is THE rule framing all comercially designed beach cats, then the "ideal beach cat" needs a new and more user friendly folding system to feature a larger width without sacrificing trailerability. Reducing the dry docking area needed in beaches and clubs also helps.

Note that small cabin multihulls not much bigger then beach cats boomed after different folding systems were developed 20 years ago, notably the Farrier system.

Would a scaled down folding system help? It's hard to imagine a Farrier folding system in a beach cat, but maybe the swing-wing system could be adapted with relative ease. The extra length would not help, though: a folded ARC 30 would result too long for trailing without a permit - but still easier to assemble. Maybe a "swing-float" ARC22?

Anyway, I agree with the "no rules" approach to multihull design. Faster, safer, and cheaper is better. And that's it.


Luiz
Re: Physics will not be ignored... [Re: BRoberts] #23204
08/20/03 03:53 PM
08/20/03 03:53 PM
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MauganN20 Offline
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Sounds like the system that the H21SE uses to telescope its beam.

I have heard of the SC20. While I realize that it doesn't take THAT much more effort, it is awefully nice to just heave up the stick and off you go.

I'm still leaning towards getting a tornado at this point.

Re: Agreed [Re: Luiz] #23205
08/20/03 04:16 PM
08/20/03 04:16 PM
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South Carolina
Jake Offline
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I see nothing wrong with the telescoping beams on the SC20...we have several in our club. This system works very well unless you take into account the width of the few boat ramps we have to use. Then you might consider a way to extend the beams once on the water.


Jake Kohl
Re: Physics will not be ignored... [Re: MauganN20] #23206
08/20/03 10:35 PM
08/20/03 10:35 PM
Joined: Jul 2001
Posts: 851
US Western Continental Shelf
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US Western Continental Shelf
I am surely not an authority here, but I do have some comments that I think are uselful.

Even though I have facilitated the one man righting of a H21SE, I have never seen either a H21SE nor a SC20 being expanded from trailering width to sailing width.

But I would like to point out one thing that is quite obvious to me, that a H21SE is very difficult to expand to its sailing width.

While many cats, including the Stilleto 27 and the SC20 have straight cross-beams, the H21SE has curved cross-beams. They are cured as if they belonged to a TheMightyHobie18.

My bottom line:
Expanding a boat with beams that are curved, has got to be a VERY difficult manuever!!!!

GARY


Santa Monica Bay
Mystere 6.0 "Whisk" <--- R.I.P.
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