bigone

Running new(to me) used boat. 34 Twin 300 Cummins, very heavy farily slow boat cruise at 19-21mph, carry 275 gal. for boat and generator. Think its enough to get to the rigs, troll, get back with fairly decent weather?

bigone

sorry, from Perdido

Downtime2

Stay out of the throttles and yes. Idle out at a 4-5 gph rate. Fish, the cruise back in. Should be fine.

bellafishing

Depends on what type engine you're running, pitch of blade, weight of boat, how many passengers, seas, wind, etc..... Typically though, on a calm day with the boat full of gas and a few passengers, you should be fine.

Bob

poseidon

BigOne,

Yous should have plenty of range. The specs on the 270 HP cummins fuel burn are as follows: 1200 RPM=1.8GPH, 1400RPM=2.7GPH, 1600RPM=3.7GPH, 1800RPM=4.9GPH, 2000RPM=6.4GPH, 2200RPM=8.4GPH, 2400RPM=10.7GPH, 2600RPM=14.2GPH.

The specs for the 330B's are as follows: 1200rpm=2.0gph, 1400rpm=2.8gph, 1600rpm=3.9gph, 1800rpm=5.1gph, 2000rpm=6.6gph, 2200rpm=8.2gph, 2400rpm=10.4gph, 2600rpm=13.2gph, 2800rpm=16.8gph.

These are the published burn rate # from Cummins for thier "B" Series engines. Figure out what your cruising at a given RPM and you will have your range. Range & Cruise on anything under mid 40' is dramatically affected by sea condition and load (load in the boa that is).

With 275 Gals, you should expect maximum range based on 215-220 gals of fuel (80% of listed full capacity) so that you will have some reserve and can account for "dead" fuel - the fuel you cant get out of the tank.

Hope this helps.

Rastaman

you may also consider shutting the generator off during non essential periods. it seems like an inconsequential burn of fuel but they usually take from one tank, which makes the level in that tank your limit. If its set up right your generator pick up will be higher than that for your engines so it will go out first.

a couple of times on my previous Cabo we stretched the range and used different tricks like shutting the generator off, trolling out and home once we got into deeper water and staging the trip by running to the double yellow or petronious tying up and shutting down for the night.

you could also consider a soft sided fuel bladder on your first trip to give you some confidence.

last thought: remember that you need 20% or more contigency for rough weather. with a heavy boat you will burn more fuel coming home facing 3ft seas!!

38bat

Sounds like you got some good advice. We have a 38' twin diesel and another tip if you need have the range is to shut down one engine. I can run on 1 engine at displacement speeds and get tremendous economy. Makes for a slow ride at eight knots but it is an option if you are worried and will save you a bunch of money in fuel to boot.