Figuring fuel burn?

8v92's should burn 9-10 gph for both at 1000rpm's. At 800 rpm's your looking at 7gph probably.

you assume the potential purchaser is looking to run the boat as a cruiser. If I was asking Dave his fuel burn, I would want to know it at his 19 knot cruise. why would you all assume this person is interested in running a sportfishing boat at 8 knots? I've been looking at moving up for the last 18 months and never wondered what the boat burns at 8 to 10 knots, since I either run it at trolling speed, cruise or WOT to run in from weather.

some of us have something more important than a stateroom hanging off the aft of our boat!

btw- I troll at a fast idle 7 knots burning about 4 gal an hour, 1 gal for the gen set, so that would be about 1.4 gal per hour. hard to figure someone who would run their boat with it in gear with no fuel. the engines would load up in a matter of hours. the potential purchaser needs to find a boat meant to cruise at that hull speed, not a convertible meant to cruise at 2.5 times what they want.

Because if you are buying the boat and have to take it long distances to get it to where you live, it's a huge factor. For example from Key West to Cancun it's 345 NM and there are no stops. So you do 8-10 knots through the night to conserve fuel, safety and it increase range and at first light you hook up and run at cruise. Also 8 to 10 knots is trolling speed if you're trolling artificials for Marlin.

Also you can run DD's at 800rpms-1000 rpms for 4-6 hours, then run them up to cruise for 1/2 an hour, then back down for another 4-6 hours. If you're delivering a yacht north and have to run the ICW the whole way, there are some days you might not even get a chance to run it up to cruise at all. If the boat travels a lot, and you have a crew, why not run it like this and burn 1/5th of what you'd burn at cruise to get it there.

oops.... .7 gal per NM roughly

I troll marlin at 7 knots here in the GOM. thats idle and it seems to work for the fisherman down here.

Capt J, I appreciate your comments and understand where you come from. using your trip of 345 NM, if a boat runs 10 knots and burns 7 gal per hour or 10 gal per hour, the difference is approximately 350 gallons at 3 per gallon or 1 grand extra for the trip. not enough for me to not buy a boat because I can't take it home.

ssems to me the person asking the question would be asking it for all the time they would be running it other than the 35 hours (using your trip).

Dave, tell him more fuel than your Hatteras, but a much better ride in the rough stuff!

On the cancun trip, you have to go slow because you can't carry enough fuel to run at cruise the entire trip, nor do you have enough daylight. So it is what it is.

Tell me about it. hehehee..... I did the great loop (5300NM) on a 75' Hatteras MY and burned less then 7500 gallons for the whole trip. Not to mention we anchored 75% of the time on the trip with the generator running all night for simplicity. It took 3-5 minutes to drop the anchor. Versus 45 minutes of securing the boat, putting out fenders, shorepower cords, water hose.....each way. Had I run the boat at cruise everyday when I had the opportunity, we would've burned 25,000+ gallons. I saved the owner $80,000+ on fuel, with an additional crew expense of probably of less then $10,000 (extra days, extra crew, food etc).

I did a straight shot from Ft. Lauderdale to Beaufort, NC at 10 knots for a little over 2 days and cut out over 250NM by following the coast, and we picked up another 2-3 knots from staying in the gulfstream the entire trip.

It also saves you 2 hours each day at the fuel dock, filling up the 1,000+ gallons you burned each day, and you only have to fuel every 5th day. If you're full time crew it really saves the owner money. A lot of times it also saves having to rinse and chamois the entire boat down.

On the 103' Johnson I work on from time to time. Sometimes we run at cruise (19 knots) the entire day, then spend 2-3 hours topping off the fuel tanks, depending on the owners schedule. Then rinse/chamois for 2 hours, after getting all of the lines and fenders on and off each day. If we have the time we'll do 12 knots or less, and do 2 days at sea or so before stopping, and cover greater distances if we ran at cruise everyday. It saves us (crew) a lot of physical work as well as the owner a lot of money, so long as you have enough crew to cover the watches. It's easy do do a few watches everyday. I enjoy 10-12knots as most yachts are very stable at this speed and you can walk around, cook, or whatever without hanging onto everything.