Building your own kayak or canoe is pretty easy usisng the strip building technique.
Very usefull books about this subject can be found at "Wooden boats"

Design 1
Clear lines, kayak suitable for inland waterways kayaking

Section comparison
In the figure below you se a comparison between a more plumb sectioned canoe (blacline) and a nimble sea-kayak (blue line). The sea kayak is considerably less stable as there is less volume under the waterline further from the centerline.
The more circular shape of the sea kayak means less resistance (the ration surface area/volume is better)
The skeg attached to the hull of the seakayak is clearly visible, this skeg helps the cours-satbility considerably. cours-stability is the tendency of the kayak to follow a straight line.

Design 2
Nice canoe, personally I do not like the tumble home of the standard canoe sections so I have drawn plans without tumblehome and with vertical ends to the sections

Some pictures with great ideas on the internet
There is much more wher these came from, have a look around and you will find websites, with how to build stories etc.

Quite intersting website about building a canoe
The link I got the pictures form is not working anymore, hope the buildier will conatc me. Then I will add a link.