Fuel burn on 265 express

[seafarer94]

Hi guys,

I have been looking at your guys number on your fuel burn on your 265 express and I am liking your numbers better than what I am seeing. I am running a 2005 265 express with twin 225 Yamaha four strokes spinning the factory props. I am getting about 1 mile to the gallon and was wondering what props you guys are running or if you guys have any suggestions on my fuel mileage. My props are in good shape no chips or gouges. My bottom is heavy with bottom paint, but I am not sure if that is the cause of the fuel burn difference. I am panning on having the bottom paint removed this winter as this boat is fairly new to me. Any suggestions would be great.

Thanks

 

[captain swag]

2012 Merc Opti 225's with Rev 4 17". Cruise in avg 2' to 3' 2 to 2.25 mpg. I believe the four blade allows significant stern lift and reduced drag as a result. At troll we burn about .2 to .3 at around 6 knots per.

 

[Fowl Hooked]

I've got the same hull and until last spring was running the same engines and factory original props. I also have 10 years of bottom paint build up - which I really need to media blast and redo as it's rough and chunky but probably makes my rig very similar to yours. With a typical load of 100-125 gals of fuel, 3-4 guys, ice and gear I was seeing 1.6-1.8mpg running at 3800rpm which pushed me along at about 25-26mph and was my most economical speed. WOT at 6000 would put me into the high 40s for speed and about the 1mpg that you're seeing. You don't say what speed you're running to see 1mpg but if its at a modest cruising speed I'd say you've got a problem, if at top end than you're likely right in line with most of us. Over to the larger group for differing experiences.

Brett

 

[drbatts]

I'm also running F225s with the original factory props on my boat, which is also bottom painted and see better numbers then 1mpg. What speeds are we talking about here? Are you getting these numbers from the yamaha gauges? If so does the gauge speed match GPS speed? There are some other variable that will influence economy i.e amount of fuel/weight, wind, current and trim. More information will help.

 

[seafarer94]

Thanks for the replies. I am easy on the throttles. I am running 3800 rpms and seeing about 1 mpg and about 23.5-25 kts. I am carrying about 150 gallons of fuel. I do have the water tank full and I usually have no more than 3 guys on the boat. Are you guys trimming your motors fairly high and if so do you guys have cavitation issues in a chop? I understand that conditions will greatly change miles per gallons.

I thought the Yamaha gauges were off at first so I calculated off the gps and gallons burned. The gauges are pretty spot on.

Thanks again for your help

 

[Fowl Hooked]

Hmmm. Not sure what to make of it now. Similar loads, same (or very similar) boat and motors, same speeds. Not sure what could be causing the fuel consumption to be so different. Conditions will affect economy but I've run mine in a wide variety of conditions of wave, tide and wind and haven't seen that much of a difference. To confirm, you're running the 15 1/4 x 19 three bladed Yamaha props?

Just spit-balling now but with the same RPMs getting the same speed I'd have thought it was a calibration issue but if you've done the math and it works out the same than it's not that. Are you calculating by total fuel burn on the gauge or by what you've burned off a full tank when you refill? If off the gauge then I guess it could still be a calibration issue.

Once on plane I typically trim up to between 2 and 3 on the gauge depending on conditions, think it's about 4 or 5 bars on the digital scale and I haven't had any real cavitation issues unless I'm running mostly flat out and make a real sharp turn - which I don't do very often, smooth turns aren't a problem. Trim tabs start out fully recessed and only get used to either balance the load out or to push the nose down if the chop warrants it as that seems to smooth out the ride but they're typically not in play. I've heard that the mounting height of the motor can impact cavitation (which makes sense) but am not sure if it would have that kind of impact on fuel economy. Pretty sure mine sit all the way down on the aluminum transom cap but will have to double check the next time I'm at the boat.

 

[max366]

I have a 2004 w/ F225s and see essentially the same performance as Foul Hooked- as long as the motors are trimmed up even a little. With the bow down, the fuel economy drops quite a bit.
Also, my Yamaha fuel management gauge is off 18-20% (reads higher GPH and consumption than actual- both engines). This has been checked by multiple (6+) fill ups/reset gauge/use 100+ gal/refill and check gauge. I wouldn't be surprised that's what you're seeing.

 

[drbatts]

My numbers are similar to fowl hooked. However I cannot get over ~44 at WOT, which doesn't matter much to me as I never run at WOT. Maybe its a trim issue, the boat definitely runs better with her ass up and bow down. My motors are mounted on the top hole on the engine.

 

[seafarer94]

Thanks again for all the replies. I was able to run her today and trimmed the motors up around 2 or 3 on the Yamaha gauge. My mileage jumped up pretty quick on the gauge. Running across the bay at 3800 rpm I was up to 1.5 miles per gallon. Thanks again for al your help!

 

[Fowl Hooked]

Excellent, good news. Keep playing with the trim and the tabs (a little bit at a time) in different conditions and you'll get her dialed in to the sweet spot pretty quick.