Can't go wrong with the 1/3rds rule.
Note: the trips I went 40 miles were up the coast rather than dead east. At least if something went wrong I would have died within site of land! Makes it a lot easier to for the coasties to recover the bodies.
Its a good idea to have at least two VHF radios (fixed mount and handheld) 2 compasses, two cases of beer, and associated safety equipment. Know your heading so if the GPS goes out you can make it back in on the compass. Know how to relay your position to the CG.
J/K on the beer....that is optional equipment.