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Re: Catmaran kayak? I have one --- almost

: Hi Bill - I just stumbled across your thread - I had the same idea about a
: year ago. I've been mulling it since, and over the Christmas break I built
: a 1/4 scale model of a preliminary design for a catamaran kayak. The hulls
: are long and narrow, 16'4" by 6", max draft will be about
: 8-9", overall beam I'm trying to keep to 24". It's basically a
: skinny hull cut in half down the middle. Seating will be from a hung seat
: above the waterline, so I guess it will technically be a SOT.

: The boat is designed as a swimmer escort and rescue kayak - the major design
: goal is to be able to transport a patient on a hammock behind the paddler
: above the waterline to reduce hypothermia. The extra load will require a
: sliding seat for the paddler to trim the boat. It is also meant to act as
: a platform for long distance swimmers to eat, drink, rest, whatever.
: Ideally, it will be stable enough that the paddler can turn around and
: move around to aid the patient/swimmer. I think it will work well as a
: chase boat at paddle events as well. I'd also like it to be fast, able to
: function on the open ocean, etc. etc.

: A plastic wrap test on the model went pretty well (it appeared to have very
: low drag), and I am currently gearing up to make a prototype starting in
: the next week or two. It will be a big experiment, as the model didn't
: give a lot of info about paddling dynamics, and there's a lot to figure
: out. I've thought about doing some software modeling, but that won't help
: with the dynamics either, so I am going to just forge ahead and make a
: boat. I plan to do the first prototype as a Yost-style SOF. The hulls will
: be nearly flat on the inside as suggested by you and Mike - they're so
: narrow they actually look more like airplane wings on edge. But hey, my
: Dad was a wind-tunnel model-maker at Boeing and my brothers and I grew up
: making balsa airplanes, not boats, so I guess that has something to do
: with it. The biggest challenges I see at this point is hull torsional
: stiffness and weight.

: I have a detailed photo sequence of the model construction. I've been meaning
: to put it all together to share on this site - I'm glad you asked your
: question as it gave me the impetus to start. The link below has just a few
: so far.

: I wanted to call the boat the "Sea Sled" but the name was taken by
: a fast speedboat catamaran from the early 20th century (now defunct,
: though). I'm toying with the name "Cutter", which has a nice
: double meaning - USCG Cutters are used for rescue, of course, but
: "cutter" is also a term for a light, fast sleigh pulled by a
: single horse, which I think is appropriate.

: Well, I guess this is maybe more info than necessary, but I've been thinking
: about this for a long time. Let me know what you think - better photos
: later, Carl

Hi Carl,
Nice concept and design. It will need a rudder for sure with that draft but it should be very quick.
The individual hull torsional strength can be fixed by an internal trellis, the torsional effects between the hulls would be low with the narowness of the hull spacing.

There are two schools of thought on crossbeam-hull rigidity. One is that they should be rigidly connected.
This works well with cabin-decked catamarans where weight isn't as critical.
The other is based on the traditional Pacific multihulls where there is a small amount of flex allowed in the connections. This allows for a lighter structure.

Mike Savage
South West Cork

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Catmaran kayak? I have one --- almost *LINK*
Re: Catmaran kayak? I have one --- almost
Re: Catmaran kayak? I have one --- almost
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Re: Catmaran kayak? I have one --- almost *LINK*
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