  LNM32/73 (7/11/73)-- MASSACHUSETTS-GLOUCESTER HARBOR- A 32-FOOTLOBSTER BOAT HAS BEEN REPORTED SUNK IN 16 FEET OF WATER ABOUT 600 YARDS, 032 DEGS. FROM BLACK ROCK DAY BEACON (LL PAGE88). MARINERS ARE URGED TO PROCEED WITH EXTREME CAUTION WHEN TRANSITING