After spending much time in New England, and boating some, pull it. Unless it is a wood hull, then talk to the marina people. While it is out of the water, clean the hull.

Once again I find myself going back many, many years so please forgive me if I get this slightly wrong.
Dep or departure is the miles between the longitude of ones point of departure and ones point of arrival. It will be different from the difference of longitude in minutes of arc.

It can either be calculated from the following formulae :- dep = dlong x cos lat or by the interprolation in using the traverse tables in Norries or other smear nautical tables.