The 56 foot long fishing vessel Silver Lady suffered an explosion while berthed at Port Townsend, Washington.   The vessel was recharging its batteries when it exploded.  The explosion damaged machinery on board, but the hull remained intact.  The Coast Guard responded quickly as the Cutter Osprey was docked nearby.   The explosion may have resulted by acetylene tanks and oxygen tanks stored near the batteries.   No reports of injuries.   The Coast Guard is conducting an investigation into the incident.