I have posted a pictorial accounting of a kayak I had built in hawaii by Hunt Johnsen. It weighed just 31 pounds with battery, battery box, and wet cell sonar transducer installed. It is a composite sit-on-top kayak. There are some good shots of the molds and on-the water shots of this kayak linked at the end of the building story. This yak is fast(5.5 MPH) clocked on GPS.

RL