These should get you started. https://activecaptain.com/ http://cruisersnet.net/ http://www.waterwayguide.com/ http://lists.samurai.com/mailman/listinfo/great-loop http://www.coastalguide.com/IntraCoastalWaterway/ http://www.skipperbob.net/
Much better going up than returning to FL If you are experienced then go offshore in displacement and use the extra 6 knots you gain following the gulf stream. Probably average around or slightly over 1g/mile but going south figure 3g/mile.
I was looking to buy one of these boats, can I safely cross the Atlantic in this boat? Would I need to add auxiliary fuel tanks? Is auxiliary fuel tanks possible? I live near Boston.
Seriously ? Short answer is no. Even with auxiliary tanks, if you could even carry even fuel, as strong as these Hatteras are built they are not designed for ocean crossing.
Go out Buston about 100 miles and shut down your engines. In 8 to 12 months you should be able to drift close enough to get towed in. Your gen-set may only offer 80 hours of run time so be frugal for heat.