You might also look at skin-on-frame construction. Its light, rugged, and can be pretty cheap to help make those novice mistakes less painful. Having built a 10' x 24" kayak for my first try at it, I'd opt for a few more feet even as a 'river' boat. A 10' kayak is painfully slow unless you are only going down stream. The frame-and-stringer "Yost" style construction is easy and requires minimal tools.

I have a "recovery" kayak built by Scott who also posts here, that was designed for mild whitewater (Scott, correct me if I am wrong). Its quite a fun little kayak, 10' x 23", handles very much like a plastic river kayak, a bit better performance than similarly-sized recreational kayaks due to the relatively narrow width. With the right skin, a SOF will be plenty durable as long as you don't purposely abuse it. I even use it on lakes, but its quite handicapped on flat water. The picture below from Scott's photo album (since I've failed to take my own photos!).

: Hello everyone. I was wondering if somebody might be able to get me pointed
: in the right direction as far as building my first kayak. I have some
: woodworking experience, and have been wanting to tackle my first boat for
: some time now. I figured that I should start small, so I gathered a plan
: to build a 12' kayak from Spira International. After talking with Mr.
: Spira for a little bit I decided that I wanted to modify his design to be
: a 6'4" kayak with about a 24" beam (Only because I would be in
: mostly rivers). I also want to build it as light as possible, so I think
: it might be best to go with stitch and glue. I was just wondering if
: anyone could give me an idea of how to start. If you notice in the
: attached picture, I want a little rocker so I have made a "keel"
: with a 1" radius that I will glue to the bottom plank to give it
: shape.I have been working in a 2 dimensional cad program to design the
: panels and I have attached the design to this post. I know this is a long
: post, but I really want to get started building this so I can take it on
: the river this summer.