I used pry-outs on one boat and I was getting 100 water seal. I used the larger round on on the back deck and the smaller one on the front. As Brisn mentioned, I made some hold downs for the back hatch, because I would sometimes hit it with my PFD doing an extreme lay-back roll. I made my own with some scrap plastic and a screw. I never did that on the front one with no problems ever. The only other thing is that I put a string grab loop on the covers for easy removal.

http://www.beckson.com/prydp.html