H9943/81--OPR-J217; UNIDENTIFIED OBSTR FOUND BY ECHOSOUNDER INVESTIGATION; 57 FT SHOALEST DEPTH; LOCATED IN LAT 30-14-15N, LONG 87-12-04W; POSSIBLY ADDITIONAL BRIDGE RUBBLE (SEE AWOIS #761); EVALUATOR RECOMMENDED CHARTING AS SUBM DANG OBSTR. (ENTERED 1/8