Has anybody here ever participated in a cardboard boat race? Some of us are signed up for one here in Key Largo tomorrow. The "regatta organizers" provide cardboard, a roll of duct tape and a paddle, and you have to build a boat in about an hour or so.

It has to be able to carry two people out to a buoy and back to shore (hopefully without sinking).

Any suggestions on what to do and not do?

I'm thinking a sail and hydrofoil leeboards. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Do you think it is possible to build a catamaran out of cardboard?

Well, I have never built a cardboard boat but I have raced against some guys who did. We had a local business sponsor a "trash boat" race. The rules were easy, it had to be built of anything you could find just laying around that might be considered trash. The judges looked at every boat prior to letting them sail and they actually DQ'ed some. The challenge was to travel across 400 yards of lake. Being that I am a cat sailor I had to try and build a cat.
I used about 20 five gallon buckets all stacked together 10 on each side to make pontoons. Then I used boards to make crossbars and a squared 2x2 to make the mast which I set up sloop rigged using an old blue tarp for the sail. I even made daggerboards that I could pull up and a rudder that would fold up and down.
It was no Hobie but considering everyone else was paddling tubs or boxes of some kind, I smoked everyone. I think the wind added to my win. It was blowing well over 20 mph running right down the lake. The waves were all whitecapping and coming over the side of the cardboard boats and other monos.

If I had to build a cardboard boat, I think I would go with something like a kayak, don't try and make a tub like most people do, you will sink and it will not have my strength. In my mind a kayak would be more stable and it would faster. That is just my idea!

I think I'd go with closed hulls rather than sit-in hulls because of the flexibility of the cardboard. Something slender like a catamaran hull. You could even build in some bulkheads to keep the hull stiff where you plan to sit. The bulkheads could also be used to make multiple watertight compartments to reduce your chances of sinking. Then I think I'd add an outrigger of some sort. Sit on the main hull and paddle away.

Do we get to see pictures of the result?

If you could put bands of duct tape around the hull where the bulkheads were you would have quite a rigid hull all you need then is some carbon and resin and you have a blade

Try to avoid large flat surfaces, These are very weak and fail easily.\

A multi chine hull would be a smart move. Lay down the bottom panel (do not make it too wide, length it NOT limited) and have the sides meet at the ends. Make a nice (side) curve from end to end). Then bend (curve) this bottom plate upwards and give it a nice curve over the full length. Hold this curve in place and then hold another plate to the side under say a 30 degree angle and mark the curve at which this plate touches the bottom plate. Cut this curve out in BOTH sideplates. Then attach this curve to the one of the bottom plate and tap it along the seam on both sides.

You now have the beginning of 3-dimensional hulls. Repeat this trick again, now with vertical sides.

You can either stop now and leave the boat open on top or make a copy and tape that to the bottom halve and end up with a closed hull like for a cat or kayak.

Somewhere in the proces you want to add some bulkheads. These are not really needed for strength but they do keep the sides in place and thus remove the risk of buckling failures. Add about 5 to 10 bulkheads depending on the length of the hull. 10 for a 16 foot hull should be enough.

If you do this right then you'll be surprise how strong and stiff these card board hulls will be.

Something comparable is indeed used to make ply Taipans and ply A-cats out of 3 mm ply. And a plate of 3 mm ply feels just like thick paper.

If you cardboard hull were to be saturated with something like expxy then the hull would survive for years.


Good luck.

Wouter

Do you only get one roll of duct tape?
how much cardboard can you use?
what other materials can you use?
what can you bring with you on the boat?
Are you allowed to paint it? or do anything to the carboard?
Do the rules allow you to add anything,poles, bottles, milk cartons?
whats the total distance to the buoy and back?
how many people will it need to support and the weight?
any glue allowed?

All the cardboard you can salvage out of the pile. They provide one roll of duct tape, and that's the ONLY thing you can use to stick it together. It has to carry two people. One paddle is provided. You have about one hour to build the boat with the cardboard and the duct tape. I don't know how far it is to the buoy and back to shore, but I'm sure it probably is less than a hundred yards.

All is irrelevant now, because our team has abandoned the cardboard event. They took their cats out sailing and decided that was more fun. Dave and Leah on their Nacra 6.0, Chip and Barb on their Nacra 20, and Rick on his Taipan 4.9.

Thank you all for your input on cardboard boat building. I am going to save it for future reference. Maybe we can do an event like that at one of our regattas if we have an off day.

To bad, I bet the event would have been alot of fun, an good laughs for all involved. I had some neet ideas on it to.

The event was held -- it is a part of the annual Island Jubilee festival in Key Largo. It is just that our team did not make it. Oh, well, I will save all the R & D for next year.

To get ideas for next year, go to Google and search for "milk carton boat".

The Minneapolis Aquatennial sponsors an annual milk-carton boat race. There are pictures and information on the web, about the milk-carton boats, that should transfer to plain old cardboard. Good Luck next year!

Thanks, everyone. We missed our chance to be on national television. <img src="http://www.catsailor.com/forums/images/graemlins/frown.gif" alt="" /> There was a brief clip of the race on the Fox Report Monday night.

Here is the result of a race done at our club.

Materials:

2 sheets of plywood
2 2X4/s
1 roll duct tape
1 8X8 tarp
1 lb of fasteners