What are the soundings on this chart measured in?

Which of the following describes the passage between Great Gull Island and Plum...

At 0726 you depart Lake Montauk with light 1 close aboard and set course 065° pe...

At 1014 you depart the entrance to Lake Montauk with light "1" close aboard. You...

At 1018 your position is LAT 41°14.4'N, LONG 72°07.2'W. At 1036 your vessels pos...

At 1020 your position is LAT 41°11.0'N, LONG 71°50.0'W. You are on course 056° p...

At 1113 you are in the entrance to Great Salt Pond on Block Island with buoy "5"...

At 1256 your GPS position is LAT 36°57.0'N, LONG 75°41.0'W. At 1336 your positio...

Your 1302 position is LAT 37°14.7'N, LONG 76°22.7'W. You are turning for 9.6 kno...

At 1712 your GPS indicates a position of LAT 36°54.8'N, LONG 75°39.8'W. You are...

At 1815 your position is LAT 41°05.5'N, LONG 72°47.3'W. You are making turns for...