Io is a simple and fun child's kayak that can be built over the course of a weekend or two. Designed by Nick Schade, the Jupiter Point series also includes an adult-size kayak called Ganymede. This cute little boat design has a peaked fore-deck to shed water and a raked cockpit that provides easy entry without being too big.
I originally made this boat for my nephew Peter when he was 5 years old. He took to it immediately. Since it is not meant as a stable boat the first thing I had him do was capsize. He enjoyed this so much that he did it another dozen times before heading out on a paddle. Being 5 this expedition amounted to out around the raft and back, but it didn't take him long to figure out how the paddle worked and how to steer and go straight. I made a very simple Greenland style paddle for him out of a short piece of 2 by 3.
Nick Schade, designer
The construction of this boat is very simple: three pieces of plywood for the hull, another three for the deck and an easy lamination for the coaming. The inside and outside are both covered in fibreglass and epoxy. Built like this it is rugged and should last several generations. It is light enough that if you are in another boat beside your child you can pick up the kayak, empty it and help the child climb back in after capsizing.
It should have enough buoyancy for kids up to about 80 pounds (36 kg).
As Io is meant for children, it is up to an adult to make sure it is used safely. You should expect that they will capsize in this boat and you should encourage them to try capsizing right away so they know what it is like. It is probably a good idea to have them wear a life jacket at all times and be comfortable swimming. You will probably want an adult very close by at all times.
Plans for the Io kid's kayak are available for free download from Nick Schade's website.