See our HowTo section for pictures of butt blocks and splices. For small boats we usually specify butt blocks. A butt block is very simple: a piece of plywood epoxy glued on top of the two pieces to join. Very often we use that extra thickness in a strategic place as a reinforcement. Often, we hide it between frames or under seat. Another method used on larger boats is a fiberglass splice, same principle but with fiberglass. It is important to use biaxial as we specify because of the fiber orientation. In all cases, the seams between plywood panels are also joined but the fiberglass seams of the boat. For larger boats, they are covered by several layers of glass in and out. The resulting joint is always much stronger than the plywood: try to break one of our butt blocks or splice and it is the plywood that will fail, not the joint. Visit our builder's web sites for pictures of the two methods.