How to build...

[Capricorn]

Hey guys, I need a bit of advice and decided that I should go and ask some of the professionals about the subject.

My class is requiring me to build a boat that cannot exceed 8' in length, 2' 10' in width and 5' in height (basically, it has to be able to fit through a door). I have no assigned specs or materials besides the above measurements. The boat must be self-propelled, and my limbs cannot reach outside of the hull. The boat needs to be able to get from one side of a lake to the other, and I cannot test the boat prior to the actual running. I have about thirty days before the boat must be tested, and I can only work with a $150 dollar budget.

This is where I need help: What kind of materials and what boat design would suit my needs for the above limitations? Any help would be appriciated. Thanks!

-Capricorn

[SeaSpark]

Take a look at this thread:

http://boatdesign.net/forums/showthread.php?t=11130

Lewisboats has a nice and simple cajac design there, you will have to shorten it but it is a nice start.

Low-grade triple layer ply will keep you afloat.

Use the "stitch and glue" method for joining the panels see http://bateau2.com/content/view/46/28/ you can replace the glue by self-expanding foam used to insulate houses. Spray the foam on the inside of the seams.

Stability:

A 8x2 feet boat will hardly be stable enough to carry a person, is it allowed to have a kind of foldable outrigger? Google "proa" to see what i mean.

Self-propulsion on your 150 budget will be hard but i will try to think of something.

[Capricorn]

Thanks for the information sorces, they're sure to bring me a long way.

I consulted with my instructor, and my bad. I'm simple so I didn't think about turning the boat on its -side- to get it through the door. So, it can either be five in height, or five feet in width. So, basically, if it makes it better, the measurements would be: 8' length, 5' width, and 2'10 height.

Thanks again!
-Capricorn

[lewisboats]

The trick here is to read into the parameters....the boat has to fit thru the door, doesn't mean it has to be right up. Sideways the hull looks better with 8ft length, 5 ft beam and 2 ft depth. This is something I can work with! Looks like a LilJon (6 year old design of mine) You won't even need the 5 ft beam...works better with less. You should be able to hand them back about half of the cash. The question is the propulsion. You said nothing about motors or such. I would assume that this is for paddle or oars, perhaps sail but nothing mechanical?

Steve

[lewisboats]

bypass

[lewisboats]

OK, here goes....8' long, 3' beam, 15" deep, 3 1/4" draft at 250 lbs ....TaDa! Uses 99% waterline length at 250 lbs for a hull speed of 3.8 kts or about 4.2 mph. You're gonna sweat to get that! 1 sheet of 1/4" for the bottom and one sheet for the sides, with a bit of an extension. Cut the panel in half and add the bit in the middle. Transom should come out of the leavings. Use chine logs for easy assembly, PL premium to glue it together and cheap paint to waterproof. I would guess about $50 or less using cheap luan. Seat center should be about 3' 9" from the transom for proper ballance. Boat weight about 35-40 lbs so you can figure up the people weight. OH...and you can build it in a day, let the paint cure for the rest of the time.

Steve
PS: it's butt ugly too but that wasn't part of the criteria
PPS: you can pick your shear, it won't matter much so long as it isn't too deep at the beam.

[Capricorn]

Alrighty, thanks for the assistance, it truly is appreciated, especially from someone who needs all the help he can get.

I'll get to work on this, and be able to tell you whether i'll make much use of my water clothing or not.

Thanks yet again,
-Capricorn