According to a CG report, a vessel was offshore tied to a rig while the four occupants slept.  One occupant awoke to find water in the vessel so they cast off and ran the boat on plane.  Shortly after turning on the outboard engines, the flooding increased.  The boat capsized and the four people with dog were located on top of the hull.  They were rescued by a fishing vessel.  The vessel was left adrift and could not be recovered.  THe operator had recently recaulked the thru-hull fittings and believes one of these failed.