Here is a general distance to fishing ground according to what type of trip you are going out on:

All Day Cod Fishing: 15 – 25 miles from the mouth of Gloucester Harbor

Half Day Cod Fishing: 10 – 15 miles from the mouth of Gloucester Harbor

¾ Day Cod Fishing: 10 – 20 miles from the mouth of Gloucester Harbor

Night Blue Fishing: Within 3 mile of the mouth of Gloucester Harbor

Evening Cruises: Within Gloucester Harbor and inner harbor