Operator/Owner were heading out to go fishing when a wave came over the stern and swamped the boat.  According to operator the boat capsized within a minute sending everyone into the water.  All persons were wearing pfds.  Two out of the 3 men were able to climb on top of the capsized vessel.  Injured was unable to stay with the vessel and began to drift away.  CG was called but in the meantime a nearby vessel rescued the three men.   According to Harbormaster who responded to the accident scene there was heavy fog and poor visibilty.  Seas were very rough with waves 4-5ft.  Winds were strong.  These sea conditions were determined to be the cause of this accident.
Barnstable                    