Plans for a True Small Trimaran at Chesapeake Light Craft
A new small trimaran may be in the works from the guys at Chesapeake Light Craft. It’s an idea that John Harris, President of CLC, has had for awhile. (I know this because I first spoke to him last year about it).
Actual development, however, sounded far off. So I was really appreciative when one of our readers here at smalltrimarans emailed me a link to the following webpage that he’d recently discovered on CLC’s website.
The article provides some excellent information about the performance challenges of setting a sail on a traditional kayak, putting double outriggers on it, and then automatically expecting Hobie Cat-like (or more appropriately, Windrider-like) performance.
It’s not gonna happen.
The reasons why are explained in great detail inside this article at Chesapeake Light Craft, which compares a kayak that has a sail on it versus a true sailing trimaran that is in the size and weight range of a kayak.
At the end of the article, the writer states the following:
“If you’ve read this far and wondered what it would take to compete with the fast cats in a stitch-and-glue design that you could still cartop, here it is. This soon-to-be-prototyped CLC kit is 15 feet long and will manage 15 knots. Alas, we don’t have a release date. We may need to break a few of them before letting this little racer go free in the wild!”
Click on the image below to see the enlarged version (I’ve linked directly to it at CLC’s website) …
New Proposed Small Trimaran at CLC
So I contacted CLC and was able to gather a few of the goals (at least in theory) for this proposed new small trimaran design. Here is the short list:
– This craft would feature a powerful rig (unlike the one currently used on kayak/double-outrigger configurations)
– The crew, most of the time, would be on external seats, using the cockpit as a footwell
– In lighter conditions a sailor could sit down in the cockpit — Windrider-style
– The cockpit itself would be roomy (unlike a kayak) and the seating would be much higher and thus quite comfortable
– Final weight after construction would be as light as possible
The original Beta builder for this new proposed design ended up building a different boat. So an immediate prototype isn’t in the works yet. But here is hoping :-)
Having a truly light small trimaran on the market that offers speeds approaching 15-knots (in ideal conditions, of course) and is also relatively inexpensive to build would be very cool. The challenges of designing such a boat, as discussed in the above article, are formidable. If anyone has the means and ability to do it though, it’s the guys at Chesapeake Light Craft.
I hope they pull it off.
By the way, if you haven’t listened to the interview Jim Brown recently conducted with CLC’s owner/boat designer John Harris about John’s new proa, then you can click here to listen to the clip at OutRigMedia.
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August 13th, 2012 at 6:52 pm
It’s a very sleek and sensible looking design and will be neat to see one in action…
a couple of points about the design parameters listed in the article-
The structural aspect is certainly a huge issue but most designs I see tend to stick to very traditional sailboat design technologies where the hull structure and skin is used as an integral part of the staying of the rig and as a result takes on additional weight…whether through clever design or use of high tech materials or both it would seem entirely possible to create a framework built around and including the crossbeams that could support the rig and provide suitable beef for attaching rudders, boards and running rigging by itself, so that any beefing up of the hull structures beyond that needed to hold their shape could be kept to the points where the hulls attach to that framework, which will always be more substantial to begin with. The hull skin then becomes little more than a means of keeping water out.
But it is this part-
“The outriggers (“amas”) need to be very large to handle racing-cat speeds. The rule of thumb, if you’re designing a sailing trimaran from scratch, is that they need to be 120% to 200% of the displacement of the entire rig.”
-that I find puzzling in light of the fact that vessels like mono racing skiffs and sailboards regularly reach and even surpass racing cat speeds without the use of *any* outriggers (or foils). This rule of thumb may hold true for a boat designed around a kayak, but it seems to assume that ama displacement is the only available means of stabilizing a trimaran…it’s especially puzzling considering that the design featured places the crew away from the centerline- presumably to windward- and by default that leverage provides non-displacement righting moment. Sure, it requires physical exertion, but in a racing context that’s pretty much accepted as part and parcel of getting high speed out of a small boat.
Another factor that significantly affects the required righting moment is the leverage of the sails themselves that is always trying to push to boat over to leeward in a more or less traditional fore and aft rig…again, looking at sailboards there is another solution, which is to convert some of that wasted energy to lift by tilting the rig to weather-
“A direct consequence of the “Free Sail System” of Schweitzer and Drake is that in strong winds the operator inclines the sail to windward, rather than allowing the sail to heel away from the wind as is the case with all conventionally rigged sailboats. Because the wind-induced force of a sail (or aerofoil) is always perpendicular to its surface, when the sailboard sail is inclined to windward it has a portion of this force directed upwardly against the downward force of gravity. This upward force lifts the hull partially (or even completely) out of the water, thereby reducing its frictional and wave making resistance, and increased speed results. ”
http://www.wingo.com/chriswhite/tiltrig.html
-the above is a fairly complex means of achieving the effect; studies of crab claw designs and delta shapes show that similar effects can be had using those designs-
http://www.multihull.de/technik/t-slotboom_gb.htm
- combined with the lower aspect ratio and reduced weight aloft of those designs, this introduces quite a bit of range to the forces involved and many possibilities for adjusting the interactions between the various forces at work.
There’s certainly a lot to be said for traditional fore and aft rigs and they probably make the most sense overall for most recreational applications…but at the same time, their design development has almost never had anything to do with what is best for multihulls, and many of the features commonly thought to make them higher performance, like huge roached mains and super high aspect ratios, were developed within the context of strict racing rules designed in many cases for heavily ballasted boats- AND those rules in most cases were designed to limit performance in non-one design classes to make sailing skill the deciding factor in who won, rather than rewarding sheer boat speed born of technological superiority.
August 13th, 2012 at 7:24 pm
Wow, great comments and insight Ian. Great links too! I hope the guys at CLC consider what you’ve shared in the above. When it comes to small tris, I know you’ve given a lot of thought to merging lightness of weight and simplicity of building (at lower cost) with higher performance.
January 17th, 2013 at 4:29 pm
Thank You ! Ian I am about to embark on building a sea kayak trimaran based on the Glen L Design. I am giving very serious thought about the potential of inclining the rig to windward. ( I learned about it from Dick Newick’s boat ) Your remarks on the ama displacement ratios are quite timely. Also I concur about beefing up structure around stress points, these stitch and glue kayaks are skins, and I don’t want the rig to rip the boat apart. I am very appreciative. Jeff Jasin