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  #1  
Old 7th September 2010, 08:12 PM
Obie Obie is offline
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Default 15 foot Beam, on a 40 foot catamaran

I am looking at a sailing catamaran with only a 15 foot beam, on a 40 foot boat. It is a home build and I do not have a lot of information about it yet. It was disigned to have twin mast, side by side. However the rig has been removed. Is a 15 foot beam considered safe, for ocean cruising? The boat has a large cabin, so there is a fair amount of windeg. It also dose not have dagerboards. The hulls are glassed over ply. any help would be great.
Obie
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  #2  
Old 8th September 2010, 02:55 AM
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searenitysail searenitysail is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

Obie,

There are several designs that have been seaworthy despite narrow beams--the Prout line is one of the most obvious.

My boat is narrow by modern catamaran standards--15'9" beam, 34'6" length--but it was designed by Morrelli & Melvin as a coastal cruising catamaran, hence the ccc designation.

While my initial reaction would be 15' might be too narrow, I think before I, or anyone could make any sort of judgement it would be important to know who the designer is.

Marshall
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Old 8th September 2010, 12:33 PM
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Talbot Talbot is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

Prout did keep their snowgoose range down to 5m on the 37 ft hull, primarily in order to fit through the french canal system. However when they went to 39ft, their beam was increased significantly (see the Escale -my favourite Prout design).

IMHO, this is too narrow on a 40ft hull.
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Old 8th September 2010, 02:36 PM
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Default Re: 15 foot Beam, on a 40 foot catamaran

I would have to agree with Talbot (he typed while cursing, "Now Talbot will continue to think he knows ALL" )

It sounds like the beam was built to enable the boat to "fit" somewhere, like a slip.

OTOH, if the builder has designed a smaller rig to compensate, it might be "safe".

Fair Winds,
Mike
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Old 8th September 2010, 06:30 PM
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Default Re: 15 foot Beam, on a 40 foot catamaran

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Originally Posted by Yoga O View Post
It sounds like the beam was built to enable the boat to "fit" somewhere, like a slip.
OTOH, if the builder has designed a smaller rig to compensate, it might be "safe".
Fair Winds,
Mike
Yes agree with a designed to fit. Probably in a slip or a specific berth. However, the width is very close to the same as the 9m Catalac, which already has a very small rig for its safety. I would expect the same size rig would be necessary from a stability viewpoint, but the extra weight of the additional 10 ft of boat would mean that the performance would be "compromised" .

Walk away!
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Old 8th September 2010, 09:26 PM
Tabs Tabs is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

We need to know a lot more about the boat, sometimes unusual designs work. Does any one remember the cat the Gougeons built some years ago? 32' long 8.5' beam!

Last edited by Tabs; 8th September 2010 at 09:43 PM.
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Old 9th September 2010, 07:25 AM
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Default Re: 15 foot Beam, on a 40 foot catamaran

Tabs look at the rig for that boat, it appears to be the rig for a 16ft cat on a 16ft hull that has been extended to 32 ft. The beam would be correct for a 16ft cat, and thus the rig is matched.
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Old 9th September 2010, 09:23 AM
Tabs Tabs is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

Yes it does look like that doesn't it. However it was a very clever design by the Gougeon brothers to produce a fast performance cat that could be road trailed. For those who don't know of the Gougeons, they are the fathers of epoxy boatbuilding and have built a lot of very impressive boats,multihulls, monohulls and iceboats, which is where they started. http://www.westsystem.com/ss/history/ Although increasing overall beam is the most effective way of increasing stability, extended length will also help and the very long slim waterline makes for a very fast machine.



I'm not suggesting that the boat Obie is looking at is in anyway comparable, nor am I advocating narrow beam catamarans, but it would be interesting to know more about this one before dismissing it.

Last edited by Tabs; 9th September 2010 at 09:30 AM.
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Old 9th September 2010, 02:56 PM
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Default Re: 15 foot Beam, on a 40 foot catamaran

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Originally Posted by Tabs View Post
Yes it does look like that doesn't it. However it was a very clever design by the Gougeon brothers to produce a fast performance cat that could be road trailed.
If I remember correctly the boat by the Gudgeon Brothers had a dynamic water balast system that could pump sea water into balast tanks in boths hulls for stabilisation as conditions get rough. Also just into the windward hull if you wanted to race on the limit.
A trailerable racer that you can sleep in if you have to.

Now to the boat in question:
Large cabin, high windage, twin mast setup and only 15ft beam... does not sound like a real passagemaker to me.
It's either not a proven design or even worse a proven design "optimized" by an amateur builder on the fly to fit into a slip.

Keep one thing in mind: Whenever the time comes to selling (and it will come some day) your prospective buyers will come up with exactly the same concerns. It will be a hell to sell. The boat has to be veryveryvery cheap to compensate for this.
And stay away from the idea of upgrading it - you will never get any return on upgrades when selling such a beast.
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Old 10th September 2010, 04:15 AM
ka8uet ka8uet is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

Two danger signals: "homebuilt" and "epoxy over ply". There are lots of good epoxy over ply boats out there. There are some good homebuilt boats out there. However, the two often don't go together. I'd be very cautious. And that's in addition to all the cautions discussed above! The boat could very well be a good boat. Or she could be one of those holes in the water into which one pumps LOTS of money to cery little return. Be careful!
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Old 14th September 2010, 03:05 PM
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Default Re: 15 foot Beam, on a 40 foot catamaran

Sounds like a very early design, to me. Catamarans have progressively widened since their introduction in England, say, 60 years ago? The earliest had ballast keels and narrow beam. Now cats are about 2:1 down at the waterline, which is, half as wide as long. The current ratio gives a stable vessel that is equally resistant to flipping sideways or pitchpoling, and it's considered a good proportion for speed and room, as well.

The other odd thing is where the bridgedeck is. The rule now is much more aft than foreward, and this is the reverse. The design just seems to show a lack of experience with this vessel type, then new to the yachting world, though of course, not new to the Pacific Islanders. Putting the bridgedeck like that forward slows the boat, and makes it pitch and slap waves more.
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  #12  
Old 14th September 2010, 03:47 PM
Tabs Tabs is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

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Originally Posted by BigCat View Post
The other odd thing is where the bridgedeck is. The rule now is much more aft than foreward, and this is the reverse. The design just seems to show a lack of experience with this vessel type, then new to the yachting world, though of course, not new to the Pacific Islanders. Putting the bridgedeck like that forward slows the boat, and makes it pitch and slap waves more.
Are you talking about the boat Obie is looking at, or the Gougeon Bros racer in the pics? I suspect you mean the latter, as Obie doesn't seem to have posted any details of his boat.
The Gougeon Bros have vast experience with multihulled craft and, having bult many famous ocean racing multihulls, built about 15 of these very succesful racers as an offshoot of the wind generator blade division of their company (West). They only stopped production when the blade facility closed.
I put this boat up as an example showing that "the rule" isn't always the only answer!
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Old 17th September 2010, 04:55 AM
georgetheleo georgetheleo is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

I just bought a Richard Woods "SCYLLA" Its 35-6 and 20-5 wide. Its epoxy cedar strips round bilge. Im going to bring it back and more as it was sadly nglected.On odd thing -it has a Cape Horn windvane. Has crossed the Atlantic twice. Ive read that Cats cant use windvane. I havent sailed it yet and Im not a Multihull sailor yet! I must rebuild the daggerboards-any advise? HAs anybody here heard of using FG poltrusion hollow planks for decking between hulls? Mine have spaced 2x6s in the area just forward of mast. and I want them out.
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  #14  
Old 17th September 2010, 05:59 PM
Tabs Tabs is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

Good luck with refitting your Scylla. I can't help with the pultrusions although it's an interesting idea. Why not go back to the trampoline Richard Woods shows in that area? (with a central walkway)

The windvane self steering is well worth having, IMHO. See this thread:

http://www.multihulls4us.com/forums/...read.php?t=368
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Old 17th September 2010, 06:57 PM
georgetheleo georgetheleo is offline
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Cool Re: 15 foot Beam, on a 40 foot catamaran

Well the planked deck area kinda 'feels good' but the best seems to me would be HD FG pultrusions as a central walkway both across the area mentioned and to the bow plus dacron webbing fastened to HD FG pultrusions alongside the inner hulls to hold the Dacron webbing trampoline. Now we have light weight , strength, non- rotting materials, and a firm place to walk to go forward to anchor or whatever--- plus a firm area alongside inner hulls to place ones drink on . By the way-I feel these FG pultrusions have a place in boatbuilding for many uses. Go to www.strongwell.com and www.libertypultrusions.com for info.
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Old 17th September 2010, 08:21 PM
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Default Re: 15 foot Beam, on a 40 foot catamaran

Quote:
Originally Posted by georgetheleo View Post
Well the planked deck area kinda 'feels good' but the best seems to me would be HD FG pultrusions as a central walkway both across the area mentioned and to the bow plus dacron webbing fastened to HD FG pultrusions alongside the inner hulls to hold the Dacron webbing trampoline. Now we have light weight , strength, non- rotting materials, and a firm place to walk to go forward to anchor or whatever--- plus a firm area alongside inner hulls to place ones drink on . By the way-I feel these FG pultrusions have a place in boatbuilding for many uses. Go to www.strongwell.com and www.libertypultrusions.com for info.
Your call, but many feel that the ability of the foredeck to vent air and let water pass makes you safer in storms. Also, of course, you need to be light in the bows to rise best to the waves, and will pitch less with less weight there. Depends on where you want to go, and what you want to do, I'd say. If mostly sheltered water, it should be fine the way it is. If offshore, or along open coasts, I'd go with the tramp.
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Old 27th September 2010, 05:00 PM
Sandy Daugherty Sandy Daugherty is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

I would go back to the drawing board, Richard Wood's drawing board in particular. I say that because I haven't designed a great number of successful boats, and sailed all of them, while he has. I wouldn't stay enamored of any particular new feature until I knew how it would fit the gestalt, and Richard would be the first person I would ask. Why?
1. I am not a world renowned designer.
2. My name on some extraneous feature would not increase its resale value, something that MUST be considered because NOBODY buys their last boat first.
3. The chance that I am going to come up with a design that will break open the world of yacht design is extreeeemely slim. There is nothing new under the sun, somebody has tried anything I could think of before. I'll find it on the internet. The chance a few people will be mildly amused by my amateur bumbling is a better bet, but not what I wanted to do. Everybody wants to be a director, and everybody wants to improve on the script.
4. If it breaks, and someone is hurt.... well, finish this thought on your own.

Back to the dying dream discussed by the OP; An unballasted 15' beam creates a challenge, but creative thinking could help. A certain weight requires a certain sail area to perform to a certain expectation, but sail area can be distributed in many ways. This boat might work with a Ketch or Schooner rig. Gaff headed sails have a lower CP, too. If it ever had side by side masts, sails and rigging, it was probably tested and worked so poorly the builder removed it all. That doesn't mean this type of rig is bad.

I would buy this hull with exactly as much money as I would walk into a Las Vega Casino with. Just enough to have fun with, and still have a way to get home and pay this month's bills. There are some really shamelessly bizarre things floating around in the dusty corners of the boating world, and there is probably someone some where to love each of them. Mine was a 50 foor Ferro Cement Chinese Junk with oilfield pipe masts, lying on its crushed chine, half finished but mouldering back to its component elements in a spreading rust stain from the randomly exposed rebar and chicken wire. I still get misty eyed!

Last edited by Sandy Daugherty; 27th September 2010 at 05:03 PM. Reason: I tried to stop editing, but my hands started shaking...
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Old 27th September 2010, 05:14 PM
georgetheleo georgetheleo is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

Im going with dyneema "silver" 3/4 X 3/4 fishnet from Bainbridge Washington in forward section and dacron webbing in fore section just before mast removing most of the 2X6 s .
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Old 24th October 2010, 12:00 AM
amibon amibon is offline
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Default Re: 15 foot Beam, on a 40 foot catamaran

I am surprised by these devastating judgements on "narrow beam cats"!

Especially since I just bought a Solaris 42' which also only offers ~ 17' beam!

Although I think that could be offset by the rather low CG (dont have any plans, so just talking about the look of it) plus at least mine is a ketch so CG of sail area also is rather low.

Heiko however, with his wonderful version of a Solaris 42 with the dumped mizzen and slightly modified main according to him also sails great - however I don't know how much (if any) rough weather experience he has with his.

So if you guys say: 40' & 15' is bad, you'll probably also say that 42' & 17' is as bad? Despite that some Solaris 42 have circumnavigated?
(OK, I know the reasoning there: As long as you stick to the coconut-track, one can pretty much circumnavigate in a bathtub with a stick & sails.
However I am attrackted to less common and quite rough weather sailing grounds so I'd really appreciate if the wizzards here could elaborate?
Especially since I am totally new to the multi-scene, my last boat, a 60' steel-tank-mono was a bitch in summers in the Med but when the going did get tough I did sail in comfort (except for that ?%*!/## - corkscrew rolling, which I REALLY hated!
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Old 24th October 2010, 03:20 AM
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Default Re: 15 foot Beam, on a 40 foot catamaran

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Although I think that could be offset by the rather low CG (dont have any plans, so just talking about the look of it) plus at least mine is a ketch so CG of sail area also is rather low.
You could work the stability calculations at the bottom of my web page and put some numbers to the question of the effects of the low rig and narrow beam, resulting in a 'theoretical capsize' wind speed.
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