Inflatable Trimaran with Claw-Wing Sail

Here is an inflatable trimaran with unique claw-wing sail. (It’s another interesting one our friend Ian McGehee has found on the web.)

In my opinion, the sail itself is definitely the the most interesting part of this craft. Ian corresponded with a sailor who uses a rig similar to this on his catboat, which he shares with us below. Again, many thanks Ian. I’ve pulled the images below in from the server where the owner has published them.

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Inflatable Trimaran with Claw Wing Sail
Ian writes:

I’ve been in touch with a guy about the updated crab claw/delta wing hybrid rig that a handful of people have been messing with, and he turned me on to this boat that you’ll definitely get a kick out of (comments are his) -

Some specs on it:
length – 16’8″
outriggers length – 8’3″
beam – 7′
weight – 50 lbs boat + 11 lbs rig
main hull diameter – 20″
outrigger diameter – 12.5″
main hull volume – 750 litres
outriggers – 140 litres

“No rigid frame, the beams are inflatable frames, with the volume of about 100 litres each. According to builder, it was a mistake to taper these inflatable beams – the tapered outer parts flexing too much
in strong winds.

It has a single wing-profile leeboard on the outside of the outriggers, switched on every tack.

The max speed is ~7.5 knots, 10+ knots surfing.Last summer this boat sailed 750nm in 45-days beach-cruise on the Lake Baikal. It’s not a sailrocket, but the performance is not bad for a cruising trimaran deployed from a backback!”

To see all of the photos posted about this inflatable trimaran go to http://fotki.yandex.ru/users/adubovskiy/album/136521/

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11 Responses to “Inflatable Trimaran with Claw-Wing Sail”

  1. ian Says:

    Just to clarify, I haven’t actually had contact with anyone who built and sails this boat but was sent that link by another sailor I’ve been in contact with who has a similar rig adapted from a Sunfish lateen sail and spars, on a very nice little catboat-

    http://www.workingsail.com/sails/crabclaw/index.html

    http://www.youtube.com/watch?v=bjyva2RogeU

    I’ll let him know about this thread and perhaps he can add more or answer any questions…he’s done a lot of research into multis using inflatable technology and showed me some other boats that I had never heard of that are pretty cutting edge-

    http://www.youtube.com/watch?v=AmNb4Kff5h4

    -I had to really look to make sure that that footage hadn’t been sped up- those boats are absolutely screaming for being sailed in winds unable to generate more than a gently rippled water surface, but that model weighs about 231 lbs and carries 139 square feet of sail and the builder reports speeds of 20 kts with race sails-

    http://www.ducky.com.ua/ducky-19/

    -compared to something like the base model non-CF aluminum spar UL 20 they are remarkably matched on weight and 20 kts is nothing to sneeze at considering that the Ducky has significantly less sail area even with race sails…

    it all comes down to light weight and wetted surface and the Ducky barely does more than sit *on* the water with as close to no draft as possible- and as a result even when it isn’t moving it never leaves a minimal draft/wetted surface state that most other boats would only ever be in when perfectly trimmed out and planing.

    At that point a lot of “rules” about the “best” sailing hull shapes kind of go out the window, as you aren’t carving a deep gouge through the water and are instead sliding over it…and the other place where the inflatable concept shines is in load capacity- the UL 20 is rated for 800 lbs and the Ducky can carry 1102 lbs…so with an inflatable you probably couldn’t get any part of the hull buried enough to be going “through” the water for more than a moment even if you tried.

    anyway, that’s just one example of what can be done, and wouldn’t a trimaran with a suitably light main hull- could be inflatable or maybe collapsible skin on frame arrangement- and those Ducky hulls as amas be something to behold?… and then store in a closet when you aren’t using it.

  2. Wade Tarzia Says:

    The Russians get a lot of work done with inflatables, it seems. For what is, great idea! 50 pounds seems a bit light. Quality inflatable kayaks around here seem to be a heavier for a bit less fabric use — so what does that mean? More durable fabric? However, my 16 foot long Watertribe amas used on a small trimaran conversion weigh about 11 pounds apiece, and thy seem pretty durable. Who can say?

  3. Small Tri Guy Says:

    Hi Ian,
    Thanks for that clarification. I’ve changed my little intro above to more accurately reflect the additional info about your source for information about this type of sail.

  4. ian Says:

    Hi Wade,

    I’m guessing here but based on some of the characteristics I can see in how the shapes are laid out and inflate/droop that perhaps the material is something with a very light weight and minimal support scrim or possibly a completely unsupported sheet material like you might see in inexpensive inflatables…which is very light by comparison to the really heavy duty Zodiac type fabrics but tends to just get fatter and stubbier like a balloon if you try to make it as rigid as they are through higher and higher pressures.

    I may be totally off base but that might explain the very low weight figures and some of the slightly overstuffed look in some of the pics. The new generation of high pressure incredibly rigid airdeck fabrics being used to make SUPs and inflatable catamaran bridge decks are light, but not amazingly so- this inflatable touring SUP is 14′ x 30″ x 8″ and weighs about 36 lbs-

    http://www.towerpaddleboards.com/Inflatable-Racing-Paddle-Boards-p/bd-twr-exp-14.htm

    That’s probably not far off from a traditional foam/glass board of that size with the accompanying larger stringers and fins and all…

    dropping the size down to 9’10″ and half the thickness only gets you down to 24 lbs, which illustrates the issue with scaling inflatables- yard for yard the fabric doesn’t get much lighter the way that a smaller boat can use thinner and lighter ply or planks or glass layup than a bigger one, and the vast majority of what you got rid of dimensionally is just air, not appreciable weight.

    So perhaps the really huge future gains in inflatable will be seen at sizes previously considered too big for the available materials, where now you may be able to do the reverse and expand your hull size by double and still use the same thickness materials and gain massive amounts of volume for the cost of a handful of lbs. of extra air.

    Regardless the ability to stow these boats in tiny spaces and carry them by hand puts them in a class of their own.

  5. Kirill Says:

    Hi everybody,

    this trimaran is an experimental boat designed as a proof of concept of a “true pocket cruiser” –
    a man-portable boat with a reasonable performance and some accommodations.

    It was built last year by Andrey Dubovskiy who used it for 750nm / 45 days
    cruise around the Lake Baikal in July/August, 2012. Andrey lives in Moscow, and the lake is
    a few thousand miles away – the trimaran was transported in a 140L backpack, with some
    space left for a camping gear.

    Being an experimental boat this tri was built from some readily available PVC fabric
    (intended for inflatable structures, not boats) which required top-up pumping during this cruise.

    In addition to a better fabric, Andrey suggested the following possible improvements based on his experience with this boat: increasing the diameter of outriggers, non-tapered inflatable akas of the increased diameter (at least the aft one), bigger leeboard.

  6. ian Says:

    Hi Kirill, glad you decided to add to the information on this boat…

    Something that just occurred to me- this boat even in its fairly low tech and primitive state really stands in stark comparison to the standard inflatable lifeboats that pack in a canister seen on so many blue water cruising yachts, that are basically the reverse of a kids inflatable swimming pool with an inflatable/fabric dome tent on top, with some ballast bags to keep it upright -

    http://www.raftservice.com/marine/avon-offshore.php

    To be fair, many of those never get the maintenance they need to be at peak performance in a mayday situation, but even brand new the people I know who have actually spent time in them by necessity all say that while they are better than nothing, it may not be by much.

    The inflatable structures that make up the living quarters seem to get the most complaints, they just don’t stay in place or stay as rigid as they need to be to really provide shelter even just in high winds, let alone when swamped by waves…and because you are in a round or oblong tub that cannot get out of its own way, you *will* be swamped repeatedly. Also when they turtle you lose all ballast and righting moment from the soft bags, and the tent/cabin becomes one big ballast bag…some people have ridden out the remainder of storms like this after being capsized because it was more stable than the “right” orientation.

    Even a small ability to have directional control and momentum is often the only difference between survival and catastrophe in the kinds of huge seas that can be the reason for abandoning ship in the first place, and something like this boat that was optimized as a lifeboat for those kinds of conditions could really save lives…

    and not just from avoiding swamping and broaching in waves; the unique over the water bridge deck aspect of tris and cats makes them better suited to avoiding hypothermia than the typical liferaft where you only have a thin layer of bottom fabric between you and the water at all times.

  7. Kirill Says:

    Hi Ian,

    I’d guess that with modern materials it is possible to make a frameless inflatable multihull of sufficient size to be stable in high seas. A frameless (all-inflatable) construction should facilitate fast deployment, and it does not have to be very rigid to deploy a trysail.

    Speaking of smaller inflatable multihulls – easy beaching is quite an important advantage, which lets them cruise some very challenging cruising grounds.
    Check out this Cape Horn video of a Ducky 19 catamaran:
    https://www.youtube.com/watch?v=XXRgPRLZdGI
    Absolutely safe in 60+ knot winds :-)

  8. sooth Says:

    There’s a small sailing trimaran inflatable called trienergydiet that is or was circumnavigating, left Hout bay 2011, has a frame. http://www.energydiethd.com

  9. Small Tri Guy Says:

    Hi Sooth,
    Yes, thanks for reminding me about the “Energy Diet” trimaran. I posted about it a while ago here at the following link: http://smalltrimarans.com/blog/?p=5052

  10. Lenny L. Says:

    Wow, what an amazing boat. I wish there were plans available for inflatable boats! The materials are cheap and durable. I would purchase plans for sure!

    Does anyone know if there is a Russian website with plans or descriptions on how they make their inflatables? There was a topic on inflatable proas on proafile, but it has not progressed.

    I have an inflatable kayak and love the portability of it. There is a lot to be said about taking your boat wherever you want in a backpack!

  11. paul gourkaloff Says:

    http://gik.fordak.ru/ a Russian forum with descriptions of inflatable cats and tris built and sailed

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