I'm 144 pounds, and I built a modified S&G NH, reduced in volume by 8%. It's also on the heavy side (from my poor building skills). I notice the slapping as well.

I recently built a skin baidarka, on the light side (30 lbs.). In comparison, there's a lot less slapping.

I think each boat design has its own advantages and disadvantages. So many choices, so little time...

>>I may have the same problem as Allan as I'm around 150 pounds, which is at the light end of the recommended weight for this kayak.