OK,
My original thoughts on this are that a kayak should be stronger than a similarly built canoe.
Now I would like to use this yak for more than this race that is why I chose the combo double.
This kayak would be in the unlimited tandem class.

Design changes:
1. Rudder controls in both cockpits. This allows one paddler to sleep.
2. Longer seat straps. This may allow sleeper to lie down. This may be removed after wet exit trials.
3. Cloth hatches. All gear to be put into Dive type net backpacks. Pull over remove packs and have the lightest craft to portage. The skin in this area would be tied to the deck stringers. The cloth hatch can be laced and Velcro on top of this.
4. Nylon or poly cloth and a hapalon sealant. Something that can take some scrapes.
5. Quick replaceable rudders.
6. Reinforcement between cockpits and a sail mount. This would be removed for the race.

I have no problem increasing the wall thickness. This kayak needs to be able to land fully loaded in surf for me to be happy.

Good idea with taking along spare tubing and a hack saw. Maybe some type of hand drill, jig and rivet gun.

I am not trying to win this race, but would like to finish in a respectable time.

I would also have canoe paddles to change the mussle groups used.

Sage