Fuel Consumption Poll

[captainmurph]

I'm planning a long trip and need to come up with a fairly accurate guestimate of my fuel consumption and estimate range.

I haven't carefully calibrated this on recent trips since I had some sailing, some motorsailing and little prolonged motoring. I would estimate (hopefully on the conservative side) .9 gallons per hour at a normal 1200-1500 rpm cruise.

My boat, as operated, likely weighs in at 9000-10,000 lbs. I have a 2-bladed, non-feathering prop.

Any of you with comparable sized boats: What is your estimate on your A-4's fuel consumption (Gallons Per Hour)?

[ndutton]

I'd plan on 1 GPH and not be surprised if it ended up closer to 3/4 GPH. One GPH makes the math easy and doing better than the estimate is emotionally uplifting. The error will be to your benefit.

If, for example, you went the other way and estimated 3/4 GPH and actually consumed 0.9 GPH you'd be in a funk. Who wants that?

[Marian Claire]

A few years back I tried to keep track of fuel consumption. I was heading south on the ICW. I motor sailed, jib only, as much as I could. Also the currents work for you and against you. Plus I use a marked stick as my fuel gauge. So FWIW my consumption ran from .6 GPH to 1 GPH. IIRC. I do not have my log with me. I did use the adjustable main jet to lean out the mix before the trip. Having said all that I use the same approach as ndutton for an estimate. 1 GPH.Then monitor fuel level daily and adjust my fuel stops accordingly. Do remember to not use the full capacity of your tank in your math. My tank can hold 35+ gallons but I use 30 to allow for what is below the pickup tube.
Dan S/V Marian Claire
Edit: The MC is heavier and I have the 2 to 1 reduction so my RPM is higher but the load on the A-4, vacuum gauge reading, may be close to what you have???

[ndutton]

What's your fuel capacity Murph? How many tanks?

[romantic comedy]

I ran the ICW and got 1 statute mile to a gallon of gas. I always use MMO also.

This was on my Tartan 34, 12000 pounds, just launched clean bottom. Indigo prop, 6 kn, 2000 rpm. Some current helped, some hurt.

[captainmurph]

What's your fuel capacity Murph? How many tanks?

Right now, it is only 20 gallons and, due to the range I'll need heading down the rivers next summer, I'll either have to install another tank or refuel with 20L Jerry Cans strapped to a board and lifeline stanchions.

Even with my WM discount, it'll cost over $100. for four new Jerry Cans, vs about $350. for another 25 gallon tank, deck fill, 2-tank valve and plumbing.

I kind of like the idea of having a new tank, but love the idea of gas-freeing the 20L cans and storing in the lazarrette when I don't need them.

I agree that estimating 1 gph is pretty safe. I need to have a 250 mile range from Hoppie's on the Mississippi to Kentucky Dam Marina on Kentucky Lake (Tennessee River).

It seems that 35 or 40 gallons is still pretty tight - although I'm going downstream for all but about 35 miles on the Ohio.

I may have to consider adding a tank and carrying Jerry Cans!

Murph

[hanleyclifford]

I have run the ICW (and back) seven times in the last 19 years and have developed fairly accurate fuel consumption data. .9 gal/hr is a good figure to work with. In my case this includes a lot of running on the hook to maintain batteries while cooking with a 1600 watt toaster oven (I have two inverters including a 2500 watt unit); hence my "steaming" consumption may be down around .75 gal/hr. FWIW, adding a fuel ratio gauge (oxygen sensor activated) and an adjustable main jet gives you the ability to "dial it in"; also helps keep you burning clean.

[Marian Claire]

"I kind of like the idea of having a new tank, but love the idea of gas-freeing the 20L cans and storing in the lazarrette when I don't need them".
I have used Jerry cans for years. I have never stored them below even when "empty". Always on deck and I made a simple sunbrella cover to slow down the UV breakdown.
Dan S/V Marian Claire

[captainmurph]

"I have used Jerry cans for years. I have never stored them below even when "empty". Always on deck and I made a simple sunbrella cover to slow down the UV breakdown.
Dan S/V Marian Claire

Funny you should mention that. I'm in the process of making four zippered bags for a customer that wants to UV shield his Jerry Cans. I had planned on making them for me as well!

[Mo]

Hi Murph,
I have a C&C 30 with a 3 blade non-folding michigan prop 12 / 6 pitch. I get 3/4 of a gallon motoring at 5.5 to 6 kts in relatively calm seas. Let's say waves and swells consistent in open ocean with wind up to 15 kts. If I have sea and wind on the nose in the 15 to 30 kt range, consumption is more like 1 gallon an hour. That would be with the boat loaded (over 11,000 lbs) with clean bottom and clean prop.

The 3 blade prop might make a difference as it will indeed help keep the boat moving forward in heavier weather. This past summer we motored through Sambro Channel and a Hunter Vision 32 couldn't do it with her 30 hp diesel and two blade prop...they were getting stopped by waves. There were actually two diesels that headed into Sambro Harbor because they couldn't keep enough way on and were taking a beating.

So, from my experience on my boat, I think you should bank on using 1 gallon an hour. That is with the carb set up just right, not too rich, not too lean, good plugs, wires etc etc.

In conditions in below video, I'm 1 gallon an hour and making 4 to 4.4 kts if memory serves me correctly. Once I get the wind off the nose, and not driving straight into it, the speed and mileage improves.
[YOUTUBE]q7rJN8YAvxA[/YOUTUBE]

[ndutton]

If you decide to go with a second below deck tank

. . . we need to talk.

[Mo]

. . . we need to talk.

Oh yes, you do have dual tanks.

[roadnsky]

Want some good advice?...

Go with dual tanks AND talk with Cap'n Neil about it.

[ndutton]

OK, I've learned back channel that the addition of a second tank is being considered. We had a discussion of my dual tank system a while back including the ability to transfer and polish fuel from one tank to another.

For starters here is the thread where we talked it up, system drawing is in post #29.

[hanleyclifford]

After multiple runs down and back on the ICW I learned a few things about fuel that I'll share with you. FWIW, as always. First, if you lash a bunch of fuel jugs on deck, in addition to the obvious issues with safety and seaworthiness, you are going to look like exactly what you are - a "floater". The ability to blend in with the locals becomes especially valuable as you get into Florida where transients are viewed askance. I finally ended up with three "built in" fuel tanks, one of which is removable. It is important to be able to fetch fuel apart from marine fuel docks (good example, South Mills lock). But of course the installation must meet USCG standards. Same discussion applies to water. In both fuel and water, there is no such thing as too much capacity. Again, FWIW.