Read the book 'Deep Trouble,' which is about kayaking accidents. A number of these accidents resulted in a loss of life. Several common themes re-appear again and again in the accident analyses. One is the lack of adequate flotation. (As supplied by tight bulkheads and hatches.) You need to insure that after a wet exit your kayak will float high enough in the water for you to re-enter it and pump it out. Good bulkheads are an easy and permanent way of doing this. Alternatives are sea socks and inflated flotation bags.