Fuel Consumption

K

KenT1

New Member
May 30, 2011
19
California
Boat Info
1992 Sea Ray 370 DA
Engines
454's
Help please...This weekend my son and I made a 100 mile round trip. I was trying to get a feel for (our) new 370 DA and its fuel consumption. We topped off the gas tanks prior to leaving started out. When we arrive at the first destination we burned 1/4 tank (per engine, per tank). Then we made a short run of 7 miles to where we were to spend the night. In that short tip, the starboard engine burned another 1/4 tank. At first I thought I may have picked something up in the Starboard screw. But after putting on the swim trunk's and getting pretty darn cold....Nothing. Matter of fact the bottom, prop's and rudders were squeaky clean. In our trip back home today, the Starboard ate up the rest of its tank of fuel, and Port burned another 1/4. I avg 15 knots turning about 2800rpm with both engines synced.
Long story short; the Starboard engine had twice the fuel burn as the Port. Help my wallet....Please, any idea's
 
Some things to consider/look at. First, are you looking at your fuel tank guages or do you have flow meters? 22 year old fuel gauges are notorious for being incorrect. I just replaced mine. When you topped off, did you fill it until the gauges showed full or did you fill until the vent flowed fuel out? Did you fill up upon return and one tank took more than the other or are you going by the gauges? How long has it been since a tuneup? You might have a bad cap, coil, rotor, spark plug, etc. Has the timing or compression been checked? Are you running a generator off one tank? It's not unusual for one engine to burn more than the other but they are usually within reason. Good luck!
 
What year is your boat and what engines do you have. If they are gas engine your rpms are low you should run it at least 3400 rpms. What you should do is fill your boat up with fuel run it at the correct rpms for about 2 hours then go fill up again divided by the hours you use it will give the gallons per hour.
 
Thank you for the replies,

First, are you looking at your fuel tank guages or do you have flow meters....I am watching the gauges, no flow meters. But I thought it odd they were the same for such a long period.

When you topped off, did you fill it until the gauges showed full or did you fill until the vent flowed fuel out? I stopped when the gas pump handle popped off, nothing out the vent and wasnt watching the gauge. But they both read full upon start up.

Did you fill up upon return and one tank took more than the other or are you going by the gauges? Yes I went down today and topped them off again. The Port took 60 gallons and Starboard took 100 gallons.

How long has it been since a tuneup? Not sure, I just bought the boat about 6 months ago. I do know I have not had them tuned up yet.

Has the timing or compression been checked? Again un-sure. I would like to assume it is ok.

Are you running a generator off one tank? Yes the gen does run on that same tank. But we only had to run it for about 20 min. That shouldnt be an extra 40 gallons.

For now Im going to check the timming, plugs,etc. myself. And see about a price on new sending units...Hope that maybe the tank wasnt full and a bad sending unit...
 
You can't run at that speed! That is just about max fuel burn. Go very slow or up around 3200 to 3400 RPM.
 
Last time out I pulled up to the fuel docks and the attendant filled my boat. He stayed by the hose and when it clicked off he pulled the hose and started to put it away. The boat only took 62 gallons and I was thinking it was lower than that, however the gauge showed just under full. He tried again and it took an additional 24 gallons. That's when I replaced my sending unit. The new sender appears to be accurate and the needle bounces slightly as I'm moving, something the old one never did.
 
HUMPH said:
You can't run at that speed! That is just about max fuel burn. Go very slow or up around 3200 to 3400 RPM.
Click to expand...

I have meters, and I can't even tell you how much I burn at 2800 - I don't think I've ever paused there! Even if it were an efficient speed, the slow, plowing, bow-up attitude gets on my nerves.

Having said that however, my boat is more efficient at both 3,000 and 3,600 than it is at 3200.

IMO, every boat with gassers 5.7L and above, logging more than 20 hours per year NEEDS fuel meters.
 
Thanks for the insight. My next trip out I will run at 3000 or 3600 rpm. I hope that gives me a better burn rate. I agree with the plowing bow; It does get on the nerves. But to my defense, I was told that should be a better rpm / burn rate for my bank account. Now I am thinking the gentlemen that told me that owns a fuel dock.
 
Every boat is different. 3000 RPM is an annoying, but efficient point on my boat. At 3200, consumption increases more than speed and that trend reverses again higher up. These sweetspots are also fluid, depending on well, how much fluid I'm carrying.

Those points for your boat could very well start at 2,800... My intended "take away" is: get fuel meters! Being early in your ownership experience makes their payback even more likely.
 
Do your engines only draw off 1 tank or do you have a cross over system that allow's both engines to draw off both tanks?
 
My engines will draw off of either tank. The current config. is Port feeds Port and Starboard feed Starboard. I am getting the feeling the "sweet" spot will be a bit different for every boat. And perhaps I need to go and look into fuel meters. Does anybody have a recomendation for meters? Not looking for brand "A" or brand "X" maybe something in the middle???
 
You must log in or register to reply here.

Forum statistics

Threads
113,188
Messages
1,428,235
Members
61,099
Latest member
Lorenzo512
Back
Top