I’ve replied to Matt with skeg pictures 🙂
As for durability, I’ve found that I no longer worry – I’ve seen marine life and debris brush up through the floor enough times and it still causes concern, but nothing yet has caused a breach or puncture. I don’t drag it along shore or docks, and I only launch and land directly in the water to reduce the amount of abrasion the bottom would take. If I had to make a change to the design I would suggest a slightly thicker floor while preserving the use of 70D for the tube. That would be enough to quell all my concerns for flatwater use!