Mini kayak or kneeboard construction

I am instested in making a very small kayak or kneeboard type boat.
For kids in very shallow water.
My question. What would be a good starting material?
Would it be reasonable to start with a surfboard blank.
Large wide short piece?
Or should I look to some sort of styrofoam and wrap it in fiberglass.
I need something to start with that is cheap and easy to form/mold.
I know I will be trying different styles and sizes.
I plan to make a small boat to play in the very small creeks by my home.
Just something for fun for the kids.
More of a hobby than anything.
I have been kicking around something like a kneeboard.
But I would need a wider and bit longer version.
Eventually I would like to make a mini kayak version out of plastic.
But that is down the road a bit.
For now I am looking for a proof of concept version.
Something I can make in the garage.
I do not have any boat building experience.
I figure all you boat building creative pros can help me get a good idea to get started.
Please and thank you

Senker

 

Check out some of the cute kid's boats at http://www.svensons.com/boat/ .

 

I like building skin-on-frame, fast and inexpensive (google "skin-on-frame kayak construction"). It can be done with scrap plywood frames, 3/4" wood stringers lashed in place, and you cover with canvas or nylon fabric and paint it to seal it. It is non-toxic and very inexpensive construction method. You can build a number of variations fast and cheap until you get close to a shape you like, and than build one with the much more expensive foam core with fiberglass skin.

You can also use plywood construction and fiberglass it. But the fiberglass adds a lot of costs, and it is very toxic material to work with until it cures.

very short kayaks (or any small boat for that matter) tend to get very wide to make them stable (longer hulls displace more water and have more stablity), and shot-fat hulls tend to be hard to paddle in a straight line. You have to add a skag or rudder, or make them longer. And of course both of these make it harder to steer into a tight turn.

Good luck, have fun.

 

Petros is telling you politely to build your boats longer than you have suggested. Kid boats ought to have a minimum length of 8 feet, and ten feet would be better. The building cost of a six footer is not a lot less than a ten footer. Building time is not much different either.