RedactedNarrative: Approximately 20-30 minutes into operator's voyage he noticed the back deck of his vessel began gathering water. He observed a couple of waves break over the transom an his bilge pump was not pumping out water fast enough. He moved to the back deck and attempted to manually bail the water out but could not keep up. The vessel began to roll over and was able to position himself on top of the hull. A local commercial fisherman spotted him on the hull of his boat about 3 hours later without a pfd and called for help. Officer determined that the vessel capsized due to a shift in the center of buoyancy created by a buildup of water within the vessel directly related to bilge pump failure. The water either short circuited the pump or the pump may not have been working at all. As the water continued to rise in the bilge it caused the vessel to ride low in the water making it more susceptible for waves to break over the transom. One waves flooded the back deck the vessels center of buoyancy shifted forcing it to roll over.