I'm bothered by some of Yakmandu's comments here. My comments are in red.
Yakmandu wrote:
...my latest theory - what if the air in the hull lifts the hatch during these extended submersions. I don't think spray is the problem. Once the hatch is lifted even a little, air escapes and is displaced with water. I also think the flow of water over the hull might also create a lifting force on the hatch, much like lift on a wing. I don't think it is possible for the hatch to "lift" when it is under water. Where is the lifting pressure coming from? Air? If this were the case, everyone's boat would leak. Many boats are effectively dry. Some of us drill small holes in the top of our Island (right behind the front seat in a tandem) so that it can breath if necessary.
My sea kayaks have non-stretch webbing straps with latches to hold the hatch down. This creates a bone dry seal no matter the conditions or flexing of the hull. I am going to add these straps and latches to my front hatch to replace or augment the bungies. I just don't think the bungies create a tight enough seal. The idea of strengthening the bungees is OK, but the potential problem with "non-stretch webbing straps" is that they can distort the Hobie hatch cover leading to serious leaks....
MrMako at last year's Everglades Challenge did have non-stretch cam straps to secure his front hatch cover. Note that the straps are near the ends of the cover and that the cover is re-enforced. Cam straps have another problem. While the exterior of the cam clamp is zinc coated, there is an interior spring for spring-loading the cam clamp which is ordinary iron and will rust and fail fairly quickly. MrMako will be back at this year's EC. I will be interested in all his innovations.
Keith
