What kind of cruise range do I need?

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nyc_bob

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While dreaming about cruising I got to wondering what kind of range I would need to get from South FL to the Bahamas, cruise the Bahamas for a while and then make my way down to St. Thomas.

Are there any long stretches where I wouldn't be able to easily find fresh diesel?

Just for reference, my boat:
Fuel tank: 260 US gal.
Engines: Twin Volvo TAMD63P.
Fuel consumption from an online source (most likely clean bottom and moderate/light load):

RPM MPH Knots GPH MPG NMPG
650 7.6 6.6 3.0 2.5 2.2
1000 9.5 8.2 7.0 1.4 1.2
1250 10.9 9.5 10.2 1.1 0.9
1500 12.2 10.6 21.6 0.6 0.5
1750 14.3 12.4 31.4 0.5 0.4
2000 19.4 16.9 35.0 0.6 0.5
2250 24.8 21.6 36.6 0.7 0.6
2500 29.7 25.8 38.8 0.8 0.7
2800 35.1 30.5 41.0 0.9 0.7

Thanks for helping me dream :-)
 
Just a few things derived from what you have posted:

At 10 kts, you ( may ) get about one NMPG. With a 20% reserve, range is 200 NM, with 30%, 180 NM. At "cruise" on a plane, your range is in the neighborhood of 125 NM. ( Reserve is a "command decision". I favor around 1/3 total. Others are willing to stretch it out more than that. This is "recreational", after all. No need to push such limits at the planning stage. ).

Before you make any such trip, confirm those theoretical numbers on fuel consumption. While useful for "rough" planning, they are almost certainly in error to some degree. Better to prove the numbers before you bet your life on them.

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I've never made the trip. I will wait for others with experience to comment. But I suspect that you are "ok" within the Bahamas, but south of that more careful planning might be required.

--edit--

I suspect the consumption chart is one based on prop demand that comes from an engine mfg. Note that that means the numbers are representative of good/ideal theoretical conditions rather than the real world of currents, wind and seas, all of which will affect the range, usually in a negative way.
 
10 kts is the wrong if not worst speed. 9.5kts on 10.2gph 10.6kts on 21.6 got so figure 15gph at 10kts...

Your max range speed will be 8.5 to 9 kts. Not a fraction more over 9kts

I wouldn't rely on a magazine test but on actual burn numbers. Running in a swell or even just 3 footers can cost you 10% speed / fuel... add a current and here goes another 10%.

Just got back from the Exumas this afternoon. Your range should be ok for most of the Bahamas, at least down to Gtown and Long Island Past long island the hops become longer with limited shelter and fuel. I don't think there is fuel in Crooked or Acklins so you have to make it all the way to providenciales Worst will be the run from the Caicos to the Dominican Republic

Not what kind of boat you have but I m guesssing 40/45' based on tankage and fuel curve. Wrong boat to go that far, doable but it s supposed to be fun. Stick to the Bahamas down to the Exumas. It's the best part of the Bahamas anyway and in many ways better than the Virgin Islands If you like crowds and want to cruise the VIs, rent a boat down there. Cheaper and safer
 
I am thinking smaller than 45 maybe under 40. With that tankage the Abacos down through the Exumas to Long Island is certainly in your range. We stopped at Emerald Bay on Great Exuma because the runs to South from there are outside the scope of our ability and a stretch for the boat which is a 43 M/Y. We have run from Spanish Wells to Great Exuma on a tank easily but we hold 385 gallons. Our normal mileage is about 1.2 npg. We tanked up down there before we returned.
What you have to consider going South from Georgetown (known as chicken harbour) is that you go up and around Long Island and then you have very few places to duck into. Weather will dictate your stays and the openings on that side down to the DR are few and far between.
We decided that it would be better to either;
1) buy a boat in the BVI
2) ship our boat down
3) charter in the BVI once in a while.

Otherwise, screwing off in the Abacos and the Exumas is a great way to piss away a ton of cash while having a great time. Having done this for the last 8 years I can attest :)

P.S. Do not under estimate the Mona Passage.
 
Good boat for everything including Georgetown and North. Depending on equipment (water maker, dink etc.) you will have a great time.
 
Pascal, I read the "chart" wrong. The line I wanted to use was 10.9 mph/9.5 kts. ( Below the speed where you start to "rise on the hump". ) 9kts ( interpolating ) would be "around" 1 NMPG. Still, I would use the chart as a starting reference point, but carefully verify the numbers before relying upon them.

It was my mistake.
 
T & Cs to the DR is like 120 mm. So well within your supposed 200nm range.

On the way to the T & Cs you'd get fuel on Long Island at Flying Fish Marina.

There is a great place to stop before the jump to the T & Cs in Abraham's Bay Mayaguana. Well protected from the prevailing winds with good holding, great diving and fishing.
 
There should be more than enough places to tuck into passed Flying Fish if you keep an eye on the weather. It least I've always found that to be true.

And on a boat with that kind of speed the Mona Passage should be a piece of cake. Again with watching the weather.
 
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