: I have built a few fairly light kayaks designed with Kayak Foundry.
: I have some 15' sea kayaks that weigh just over 10kg and a 15'
: TK1 that weighs 8.3kg.

: You could get it a bit lighter than that because I used 125gsm
: (4oz) glass inside and out. The sea kayaks are made from 5mm
: strips and the TK1 from 4mm. I used mostly Paulownia, which is
: about 20% lighter than WRC. I would not hesitate to use 4mm for
: any kayak used on inland lakes. You could get the weight down a
: bit by using 3mm strips and 80gsm glass. ...

I can recommend the paulownia - I made a Black Pearl with tight weave lightweight fibreglass (about 3oz) that's 12kg with 2 interior layers, 1 external layer across the hull and roughly the same layup on the top half. I used thick foam for the bulkheads. The wood is super light. Strength seems ok thus far.