Catamaran Design

[sando61]

Hi
I dont know if it is the right place to post this question but I have to begin somewhere.

I am planning to attach two Reval Duo seakayaks and convert it into a catamaran. It will be paddled with canoe paddles most of the time but we are even planning to attach a thruster transom 54 lb motor (www.motorguide.com).

The dimensions of the kayaks are L: 650 cm (21'6'' ); W: 59 cm (23'' ). I plan to connect it with hollow aluminium pipes

My question is what is the ideal distance of the beam i mean distance between the kayaks (hulls)

[Leo Lazauskas]

Originally Posted by sando61

Hi
I dont know if it is the right place to post this question but I have to begin somewhere.

I am planning to attach two Reval Duo seakayaks and convert it into a catamaran. It will be paddled with canoe paddles most of the time but we are even planning to attach a thruster transom 54 lb motor (www.motorguide.com).

The dimensions of the kayaks are L: 650 cm (21'6'' ); W: 59 cm (23'' ). I plan to connect it with hollow aluminium pipes

My question is what is the ideal distance of the beam i mean distance between the kayaks (hulls)

It depends on the speed you plan to paddle and the
length of the hull, (and on gravity, but I'll assume
you are going to use the kayak here on Earth.)

At some Froude numbers the optimum spacing is very wide;
for others it is very narrow.

For mathematical squiggles on this topic see:
Optimum spacing of a family of multihulls
E.O. Tuck and L. Lazauskas, Schiffstechnik,
Vol. 45, No. 4, Oct 1998, pp. 180-195. (pdf)
http://www.cyberiad.net/library/pdf/tl98.pdf

Have fun!
Leo.

[sando61]

Leo
Thanx for the prompt reply. Read through the link. Esp the CAT section. I understand correct me if I am wrong for simplicity is it 1/3 the hull length
which means around 2.1 m .

[Leo Lazauskas]

Originally Posted by sando61

Leo
Thanx for the prompt reply. Read through the link. Esp the CAT section. I understand correct me if I am wrong for simplicity is it 1/3 the hull length
which means around 2.1 m .

That sounds about right, but there's no substitute for experiment here. If the hull separation is too small wouldn't that interfere with your paddling styles, unless you have one left-hander and one right-handed paddler?

I'm not sure how far you plan to travel in the boat. I suspect that at the start of the day you will be able to manage a higher speed than towards the end of the day. The "optimal" hull spacing might then be no more than an academic exercise. Maybe putting a beer on the bow will give you greater incentive to paddle faster and would lead to greater gains than optimising the hull spacing

Regards,
Leo.

[skipperG]

Hey, you might go to Jack's Plastic Welding, the make cats and look at sizes and specs.

[im412]

i'm curious why you chose not to go with one of the outrigger designs
they seem a more efficent hull form

[skipperG]

I guess you want to sit next to your first mate, have some deck space for storage on top, maybe a place to lounge or even camp on, if you get lazy you have a deck for a trolling motor/mount and a trampoline could be folded in case you want to break it down for the two boat configuration, how are you goig to do it?

[kach22i]

Looks like you need lots of little friends for this one.

http://www.mitadmissions.org/topics/...carboats.shtml

[solarventure]

Hi, I am designing a long distance solar powered boat. My main citeria is the ability to carry the biggest possible solar PV array which preferably should be able to be tracked by tilting on two axes.

Overall size of the array is 80 sqm (10.75 sqft x 80).

Low profile above water to avoid wind resistance as much as possible,

Robust design to stand up to rough seas.

Also, hull speed will be very slow, maybe 5 knots, so wetted area needs to be economical to reduce friction, wave creation not going to be a problem.

Heavy Li-ion batteries to be used as storage for all night passage and while lighter than lead acis, are still heavy due to number needed.

Ocean crossings on the cards, so stability is a factor.

This is a venture boat, not a family cruiser, mostly one person on board so accommodation to a minimum.

Now the crucial question, monohull or Multihull, and if Multihull, cat or try ??????

Please offer guidance with reasoning.

Kind regards, solarventure

[kach22i]

Originally Posted by solarventure

Hi, I am designing a long distance solar powered boat.

have you seen this forum:
http://www.boatdesign.net/forums/hybrid/

This is the thread you need to read:
Solar-Powered Boat Successfully Crosses the Atlantic

[mikereed100]

I put this together with a half sheet of 1/2" ply and 2x4's. It works great, looks awfull, handles the rough stuff well and a 2 gal. gas can fits in the stow hole of the larger kayak. It breaks down in a few minutes to 2'x4' pieces. A couple of K-Mart folding chairs makes it pretty comfortable.

Mike