  LNM5/82--NY AND NJ-NY HARBOR-NJ PIERHEAD CHANNEL AND BAYONNE TERMINAL CHANNEL- TUG ENDEAVOR REPORTS HITTING SUBMERGED OBJECT CAUSING PROPELLOR TO FALL OFF IN APPROX. POS. 40-39-29N, 74-04-12W, APPROX. 400 YD. WEST OF ROBBIN'S REEF LIGHT.  (ENT DAS 05/0