river raft race

[boatgirlie02]

what is the best way to build a really fast river raft?

[lewisboats]

Define "raft".

[boatgirlie02]

like a homeade raft that people build to race in

[messabout]

Not enough definition. Is the raft to be powered, rowed, paddled, sailed, or what? How many occupants? What kind of water? Smooth with little current, strong current with whirlpools, moderate white water, severe white water, etc.... All those things play into the answer to your question.

Boatgirlie you can be coy about other stuff that girls are priveleged to be coy about. But if you want good counsel about your raft, you must be specific.

[SeaSpark]

The moment something floating in the water becomes fast, it is not a raft anymore unless when on a really speedy river.

[boatgirlie02]

paddled, 3, smooth (race is in a no wake zone)

is that enough?

[jehardiman]

As you said "raft"...that implies ride on rather than in... which means that you cannot use rowing shells or canoes. Optimum form is most likely to be a narrow hulled cat or tri configuration.

[Rick Willoughby]

Originally Posted by boatgirlie02

what is the best way to build a really fast river raft?

Fastest for three people needs a hull about 28ft long and 12" beam. Would be pointy at both ends. Would need two small stabilisers to avoid capsize. Would be as light as you could build with the required strength to support three people.

If 28ft is too long to transport then go for a catamaran (with two hulls) around 20ft long and 8" across.

Best way with no expense would be carbon fibre over foam core. However raft implies something built from scrap or local hardware.

The type of construction depends on the building skills and materials available. You might make something interesting with bundling 4" PVC pipes together and fairing out with expanding foam (not that cheap though). You could make a very simple ply boat with hard chine (rectangular hull section) that is easy to build, still fast and light weight.

Rick

[SeaSpark]

Sorry if some of us were a bit unkind, Rick's advice is about hull dimensions is very good. When you tell a bit more about how much time and money you want to invest more ideas may pop up.

[messabout]

A simple Bateau as used by ancient loggermen would fill the bill. The boat/raft resembles a mortar box. Make it about 15'-10" LOA x 36" wide x 10" high.. It is rectangular in section with a height of only 10 inches the deck will be close to the water as a raft might. The sides are two pieces of ply, butt joined. Each piece is 10' x 96" long for a total length of 16 feet. Make a mark about 40" from each end and strike smooth curves from bottom to deck level. Three eighth ply can be bent around that curve to make the bottom. The two sides are parallel. The frames are rectangular in section. Put a deck on it and you have a barge that is manageable in size and weight, can be paddled, is easy and economical to build, and after the race is over it can be used as a waterborne lounging platform. Five sheets of ply and a few 1 x 3 sticks will be sufficient material. Cleopatras' Barge will draw about 5 inches of water while displacing close to 600 pounds.

If you want a faster raft, then construction details become more complex and it will need to be longer, narrower, pointy at the ends, more expensive to build, and building time will increase seriously.

An option is to beg, borrow, steal a 17 to 20 foot canoe, Adirondack Guide Boat, or St Lawrence Skiff. Saw the sheer into a straight line about 8" or10" above the bottom. Install a deck on the straight top line. Leave the deck rectangular in plan view so that it looks like a raft. The person from whom you borrowed the canoe may not like the boat as well when it is returned. Explanations may become neccessary after the fact.