The granddaughter I built the kayak for is small for her age and quite slim. Partly for that reason, I made the cockpit quite small so that a child who was too big for the kayak could not get in it. It is 12 ft long and 17.7 inches wide. It weighs 5.7kg or 12.5lb.

Not surprisingly, it looks quite a bit like the Parr. It also looks like a child size version of the kayaks paddled by her grandfather, grandmother, father and mother. :)

The photos below show my granddaughter when she was about 4 years old and a tall 10 year old girl. Largely because of the cockpit size, the 10 year old was about as big a child as could fit in it.

With a bigger cockpit, the kayak would support a slightly larger child, but since your son is already as big as that girl, it would probably be better to build a 14 foot version.

If you are interested and have "Kayak Foundry", I could send you the file and you could modify it to suit. Otherwise, I could modify it before I send it. You would need a copy of "Kayak Foundry" to print the forms.

I am quite pleased with the design, but of course, I am a bit biased.