I need a desighn for a cardboard kayak?

Question

I need a desighn for a cardboard kayak?

Answer 1

Having built a few cardboard kayaks for fun and competition years ago, I seem to remember that the rules differ from race to race.  Usually they will allow nothing but cardboard so no wood stiffeners can be used.  If the race is a straight line even with no turns, then you want sort of a torpedo shaped boat with a pointed bow with the boat widening out to 24-26" and then tapering back to a point  This is a basic Swedeform design where the widest part of the boat is directly behind the paddler(I'm assuming you are the sole occupant).  The length is up to you.  I wouldn't make it much longer that 12-14' unless you have a lot of cardboard at your disposal.

My boats were open on the deck side  I'd build small decks at the ends to help hold the boat together.  I used a flat hull, but supported the flat hull with cardboard bracing internally.  If you are near warehouses or big box stores and catch them on a day when shipments come in, they will usually give you their extra cardboard and slip sheets etc.Figuring out your seat will be critical and making a cardboard seat that will support your weight will take several layers and staggering those layers will spread the load over a wider area.   You want to avoid having a stress riser where the seat quits and the hull is on it's own again for support as the boat could tear there first.  also reinforce the area where your feet will be.

  If you can find a grocery store that has those big cardboard bins that hold watermelons and pumpkins, most of that cardboard is triple thickness and un-stapling it will get you a 14' long piece to start with.  You might need 2 or three of these bins by the time you make sides and reinforcement. I wouldn't make the sides much higher that 12 inches or you won't be able to reach over the sides and take your strokes.  I've also seen some cardboard "honeycomb" walls made for stiffening loads while traveling in the trucks, but you might have to really hunt for those.  Water proofing those would be tough as well.

As far as waterproofing the boat, there's the biggie.  Most of the rules books prohibit using 2 part epoxies to coat he hull and insides.  I used the yellow contact cement(it's waterproof) for the gluing and reinforcing the joints and edges and some say that good ol' airplane dope is the best for the hull.  It's a lot more money than the contact cement and the contact cement won't let you paint pretty colors and logos and such  Some use acrylic paint and some use oil based, but the bottom line is if you have to run through a few heats to get to the finals, longevity is going to be key.  You may want to build 2 or 3 of them if that's the case.  If the race is a "one and done", then maybe that's not as big a deal.  I would test out the boat before the race and make sure it's going to hold up and make sure it's stable enough so you can finish upright!!  I never had any luck using urethane varnish, even though that should've been the bomb.

A friend of min in Texas made a boat using a different technique.  He ground up his cardboard and took the dust and made a slurry of it and the glue.  When it all set up, he carved a very stiff boat out of it.  It weathered the water nicely, but it weighed a lot more than mine.  We never went head to head in competition though.  He made his hull shape from plywood and then laid Visqueen over the wood and plopped the slurry down and shaped it out as best he could.  the carving and grinding started after the mix had dried.  I think he painted it also, but don't remember for sure.

When I lived in Arkansas, they held the unofficial World Championship cardboard boat races on Greers Ferry Lake back in 1998 or thereabouts.  I finished second to a guy that had a $5000 carbon fiber bike frame mounted on a couple of cardboard pontoons and the chain drove a propeller system(the rules didn't specify that the boat had to be paddled).  A ton of work went into this contraption, but  I whined that his boat wasn't 100% cardboard(could you blame me?), but they let him race anyway.  On a course with 2  90 degree turns on it and a distance of maybe 100 yds. total, he beat me despite a rather "ambiguous" finish line.  I thought I'd crossed the line first, but se la vie.  The spectators thought I won also.  His propeller system hung up on one of the underwater cables that marked the course and he pretty much came to a dead stop while I blew by him.  The judges said he'd crossed the finish line and that was that.

Good luck with your creation.  After all, it's more about having fun that who wins I guess.

Answer 2

check it!

http://playak.com/article.php?sid=1243

maybe lol

Answer 3

good luck with that one....get a good sealant.

quick question...are you Polish?