Boston to Florida on a Searay 340

You may have problems making it from Montauk to A.C. I suggest going up the Peconic Bay and fueling at the south side of the Shinnicock locks, then going out Shinnicock Inlet. You should be able to make A.C. from there. You should have a handle on your fuel burn by then. However, check your fuel burn from Boston to the C.C. canal (fuel @ Sandwich). There's a chance you'll have to fuel @ B.I. or Newport as well. If there is any doubt about capacity from there either go up L.I. Sound or through L.I.'s south shore bays to Fire Island inlet. (If you do take the south shore bays please PM me for instructions or you will run aground in Moriches Bay.) Either will cost you an extra day, but but beats waiting on the ocean for Sea Tow to bring fuel.
I doubt you'll be able to make the distance from Ocean City,Md. to Norfolk so plan to run up the Delaware to the C & D, then down the Ches. (another extra day). The inside run from Coinjock to Beaufort will also be a problem, but if you top off at the marina at the Alligator River bridge you should be OK. Beaufort-Georgetown and Georgetown to Hilton Head you should be OK outside, but after HH stay inside to Fernandina Beach. After that you should have no problems with fuel stops.
Remember that you can't and don't want to get to the bottom of your tank so do your calculations assuming at least 20% less usable fuel than you specs show.
I think you'll find these links helpful (if you don't have your computer you can call in to Dial-A-Buoy for sea condition reports):Weather & Sea Conditions:
NBNC-NORTHEAST USA Recent Marine Data
http://www.ndbc.noaa.gov/maps/Northeast.shtml

ICW Conditions: SKIPPER BOB
http://skipperbob.home.att.net
and
Cruisersnet.net
Finally, make sure you get along with whoever you're traveling with because, even then, you may not want to see them again for awhile after spending 10 to 18 days, 24/7 on that boat with them.

I have a 37' Carver and run twin 7.4L Merc's. I have done a few long runs and given the power to weight ratio, yours shouldn't be too different. My weighs in at 21,000 lbs and runs 620 HP total.

600 RPM (idle) - 3-4 kts and 4 GPH total use.
1000 RPM - 8 kts and 8 GPH total use.
1500 RPM - 12 kts and 14 GPH total use

anything between 1700 and 3100 RPM just plows through the water, throws a monster wake and burns the crap out of fuel.

3200 RPM (lowest planing speed) - 18 kts and 24 GPH total use
3600 RPM - 22-24 kts and 26-30 GPH total use
4250 RPM - (WOT) - 25-26 kts and 34+ GPH total use.

You will, obviously, have some differences due to hull design, weight, engine tuning, trimming, wind/weather, etc.

Good luck on your trip. I'd like to know how it is. We are looking to go from central Florida to NY sometime soon...I'd rather take it to the Keys, personally.