help!

[Ebbie E]

Hi! So I'm a senior in high school and I grew up going to WoodenBoat and now in physics I have a boat project. My knowledge of boats has lost me. The whole thing is that I have to make a cardboard boat that can hold two members of my team and race it across a large pool. What I would like to know is the structures needed to make the boat and if there are any that would help it go any faster. We have to paddle like a canoe. Any help would be greatly appreciated. Thanks.
Ebbie

[JakePorter]

Had to do this first week of engineering school. Don't sweat it, just about anything will float for a while if you keep the displacement more than the weight of the folks paddling. So, lesson #1 -- safest way is to make the light guys paddle.

Next thing to remember is that your cardboard will gradually soak through and get softer and softer as you paddle across. Even the safest design will turn into a wad of wet paper after 10 minutes or so. (if you have any extra tape, use it to laminate the bottom) Most of the folks who failed lost it in the last few feet from shore because they couldn't move their boat fast enough. Risk increases exponentially with time on the water. So, lesson #2 -- make a fast shape rather than 'safe and stable' and be sure your guys know how to paddle quickly...especially if you want to win the race. Note that #1 and #2 are a trade off. The bigger athletic guy who can get you across faster may be better than the little guy who has never paddled.

There are tons of ways to do this design, but I would recommend the tried and true shapes (there is a reason canoe type boats don't very much in shape or design. A half tube with conical ends is simple and strong. So, #3 -- keep it simple.

How'd we do it? Since we only had one try and no extra matterial to practice, we went simple and safe. Ladder type frame for gunnals and thwarts (roled up tubes for framing material) and used our rear ends with legs extended to hold the bottom shape. We paddled like there was no tomorrow and made it with time to spare. Many of the more risky designs should have been much faster but couldn't take the softening of their materials as the race went on. All in all, the race ended up being decided by athletics and paddling skill. The best paddlers won. We looked traditional and boring, but came in 4th out of 30 with virtually no paddling experience.

This is probably no help at all since all of these factors are contradictory...that's what makes it such a great project. You have to weigh the risks and rewards, pick a design, and build it as best you can. After that, it's sink or swim (or maybe both...). You'll have a blast.

jake

[Ebbie E]

So I just had class and we learned the major rules that I hadn't known before. My boat can be waterproofed with special paints and glues. We get to use duct tape as emergency repair during the day of the race. Our boat can't cut anyother of the boats off while racing, so it has to go in a straight line. There are the different races such as the ultimate against one of our rivaling schools, the school championship, the turn around (go turn around come back), and the four corners where you move counter clockwise around the pool touching as many sides before you sink. All in all I need to figure out how to make a boat able to hole just over 200 pounds, able to turn around, be super sturdy, and just look good. The group has come together with the idea of a catameran(sorry about the spelling). Is that a good idea?
Ebbie

[Bruce Hooke]

I think a catamaran is going to be harder to paddle and turn than a regular canoe. Realistically, you can't get much more efficient than a canoe shape in boats this size. However, of course, a canoe shape is pretty boring.

To make the boat easy to turn add more rocker to the bottom (i.e., lift up the bow and stern).

[S/V Laura Ellen]

Hi! So I'm a senior in high school and I grew up going to WoodenBoat and now in physics I have a boat project. My knowledge of boats has lost me. The whole thing is that I have to make a cardboard boat that can hold two members of my team and race it across a large pool. What I would like to know is the structures needed to make the boat and if there are any that would help it go any faster. We have to paddle like a canoe. Any help would be greatly appreciated. Thanks.
Ebbie

It's easy to do some rough displacement calulations. Most people under estimate the displacement of the boat. It is best not to have seams below the water line. Try to minimize the number of exposed edges od the cardboard exposed to the water. I competed in a cardboard boat race about 10 years ago and used a punt style design. Didn't even get my feet wet during the competition.

Have fun!

[Thorne]

Best to get the rules in writing, so we can give you specific suggestions on material and design --- i.e. what sort of paints/sealants, how much, how long to dry, what size cardboard, etc.

Sounds like fun!

[Canoeyawl]

Building a catamaran is like building two boats…plus connecting them together -lol

[Killick]

For something that can be paddled fast, how about a cardboard version of a stitch 'n glue 2-person kayak if it will fit within the rules you have to abide by. The deck structure should really help strengthen up the hull compared to a canoe.

Do a web search for "free kayak plans" and you should find something that might be suitable. I believe Guillemot kayaks has a free (single seat) plan that would give you an idea of what I'm talking about. Should be other plans floating around (no pun intended) on the net too... Guillemot was just the first result returned by google.

Tony

[S/V Laura Ellen]

Best to get the rules in writing, so we can give you specific suggestions on material and design --- i.e. what sort of paints/sealants, how much, how long to dry, what size cardboard, etc.

Sounds like fun!

Best I can remember the rules were:

Use only corrigated cardboard (available in 4X6 sheets
Only single part glues
Only single part paints
Only latex caulk
no crews, bolts or other
paper packing tape

[Paul Scheuer]

I have some experience, here. A team of us at work once built a cardboard racing canoe for a charity event called America's Cardboard Cup. We built a 30 foot, eight place craft that went as fast as I've been in a boat under human power. See the bow wave in the pic.

The design shape was nothing special, but it wouldn't have taken much to have built a somewhat sleeker craft. We just took the basic lines off a Grumman and stretched it like a stretch-limo.

The construction was laminated - three layers of double-wall corrugated cut in two-inch wide strips. Two diagonal, one longitudinal, over a base shape of one layer of cylindrical and conic panels. Thje rules were no waterproof tape unless within two inches of a seam, hence the two-inch strips. We didn't exploit the loophole, but we did pack on a layer of reinforced packing tape. Bench seats made from the building form stations provided the internal bracing, with a little extra at the sheer. The rules also said no two-component glue. We used a single component water-dispersed, vinyl adhesive. That's the stuff that holds the bottom of shipping catons together - good stuff - and waterproof when dry.

The total empty weight was just uinder 200 lbs. The racing crew weighed about 1400 lbs.

We stayed in the water just long enough to complete our racing heats. We raced the boat for three seasons - Third place, first place and first place.


http://www.imagestation.com/picture/sraid193/pe1f83ce69e2fcd54d35c37ec1c6e2543/f18aed43.jpg
http://www.imagestation.com/picture/sraid193/p6809b9c0c273ddbbbb43954d314e7b61/f18aed49.jpg

[skuthorp]

I've built several paper-mache canoes over a mould. Concrete waterproofing as a glue (Bondcrete here), heaps of paint. We could use woooden bracing and gunwales. Lasted some years with regular re-paints. Not light! The last one blew away one night over xmas hols.

[Tom Lathrop]

I've done this kind of race with a friend. We built a catamaran. I think it was 8' long and 4' wide. The top was made into a torsion box with the interior done in a honeycomb with 2" strips of cardboard on edge. and was strong enough to easily support two adults. The hulls were of triangular cross section 12" on each side. There was enough buoyancy but only just. I'd suggest these be deeper and made double walled with some bulkheads. We used duct tape and plastic sheets for waterproofing. It lasted all afternoon after the race with kids playing with it until they hit the shore too often and it started to get soggy.

Several coats of paint and duck tape would probably be just a s good for waterproofing.

The race was to an offshore buoy and back. We experimented with a yuloh but gave it up because of our inexperience and used canoe paddles. No problem steering since it only wanted to go straight. We won the race but problems turning around cost us the lead temporarily.

Our boat was stronger, more stable and lasted longer than any others but the turning thing is a serious issue if you need to do that much. The biggest issue with the other boats was making them rigid enough since several collapsed before they got to the mark.

Since you need to turn a lot, I'd suggest a dory shape with some triangular box beams on the sheer for rigidity along with a bottom made of 4 or more layers. If you made the whole thing of torsion box panels, it would be very rigid but time consuming to make.

Paul's boat would be fast but would also not turn at all well.

[Tom Hunter]

Ebbie,

I have nothing to say about cardboard boats, but if you can't win with this kind of advice shame on you.

Good luck in your race.

[Paul Scheuer]

I should mention that the thirty-footer above was built in six weeks by a building crew of 23, working on lunch hours and after work. The challenge for the captain (me) was how to get everyone in the boat on race day. We had one absentee, the guy thought that a wedding was more important that racing. It worked out perfectly as we raced three heats, rotating three seven-person crews, with the captain aboard for all heats.

[David123]

The construction was laminated - three layers of double-wall corrugated cut in two-inch wide strips. Two diagonal, one longitudinal, over a base shape of one layer of cylindrical and conic panels

Cool...cold molded cardboard! LOL

Seriously---if you are not limited to the type of cardboard you can use, then the cardboard mailing tubes you can get a package stores like UPS are great stiffeners and would make great thwards for a canoe design.

If you are not limited as to what coatings you can use, make it as stiff as you can and spend a few bucks on a gallon of polyester resin available at Home Depot and other stores. Several light coats of that onside and out will waterproof it better than paint. Pay particular attention to the "end Grain" and seal it up good.

would be best, as thorne said , to post the rules as written here so that these folks can know what limitations you are bound by. Believe me...you're in the right place. And don't forget to post pics of your progress and the finished product.

and for cripes sake, don't let the cat out of the bag that you're posting here. The competition can access this site too! Make sure your team mates don't tell either. Industrial espionage will sink you!

[donald branscom]

Best to get the rules in writing, so we can give you specific suggestions on material and design --- i.e. what sort of paints/sealants, how much, how long to dry, what size cardboard, etc.

Sounds like fun!

Yes - lets have those rules or no more tips eh

You could use carboard (how much cardboard) and 5200
slathered all over everything. Killer!!
Make a large rectangular soft bilged tube 30 feet long, triple layers with staggered joints,and 5200 buttered on all surfaces. sort of a USS MISSOURI canoe hull. Then cut the whole thing in half longitudnally like a hot dog bun. And remember a square tube is 16% stronger than a round tube. Then after you win sell the second hull to you buddies and have a big party after.