fuel usage

any roundabout fuel consumption numbers for a 250DA with a merc 260, 1986-ish? this year i went through 105 gallons of fuel and i bet i only put 5-10 hours on it, probably closer to 7. it runs perfectly fine and was tuned up towards the end of last season. i'm running a 14.5x17 prop and usually 2 or 3 people on board. my typical day is to start it up and spend about 5 minutes idling to warm it up then about 1/2 mile of no wake then maybe a 3-4 mile run then anchor up and shut it down. same thing coming back. on plane i run about 3200RPM at about 26MPH. seems like about 15 GPH with about 1/3 of my time either idling or no wake speed (about 900RPM and ~5MPH).

does this seem about right? i'm fine with it if it is normal but if it isn't i would like to figure out why and fix it. engine doesn't load up at all and doesn't smell rich. i haven't pulled any plugs to look at them yet. i rebuilt the carb earlier this year.

example; i filled the tank 2 weeks ago and with my typical day noted above i probably have about 10 miles on plane and 20 minutes idling and about 2 miles of no wake and i'm at about 1/2 tank now (~35-40 gallons used in that short time).

my hour metr is broke but i plan to install a new one over winter to get a better read on this

The only way to really measure how much fuel you are using is to fill the tank and note the hours - then next fill up note the gallons to fill and hours and do the math to figure out gal/hour. Could not find a test for your boat, but here is a 2000 240Da with a 5.0, which is close. It shows 11.3/gal @ 3500rpm. Without an hour meter to accurately measure engine time - I think you are just having too much fun and running the boat longer and faster than you think!

[h=2]Test Results - Change Measurement Unit[/h]

RPM	MPH	Knots	GPH	MPG	NMPG	Stat. Mile	NM	dBa
1000	5.7	5.0	1.7	3.4	2.9	208	181	72
1500	7.9	6.8	2.9	2.7	2.4	168	146	74
2000	9.3	8.1	5.0	1.9	1.6	116	100	77
2500	14.0	12.2	7.3	1.9	1.7	119	104	82
3000	23.3	20.2	8.4	2.8	2.4	173	150	83
3500	30.6	26.6	11.3	2.7	2.4	169	147	84
4000	35.5	30.8	13.6	2.6	2.3	162	141	87
4600	42.0	36.5	18.1	2.3	2.0	144	125	89

you could be right Bill. my estimate may be far off but just seemed like this last tank went pretty quick so i started to crunch numbers and seemed like alot of fuel

You could always install a fuel flow meter and get real time results on fuel burn.

We get 8/10 of a mile per gallon with our boat.

i will be ordering a new hour meter in a couple of weeks so that will help me to get a more accurate measurement. i know the one day i filled it i thought i was a little under 1/2 tank so filled a 30 gallon tank and after about 20 gallons i was full so my estimations are likely off too. in fact, that may have been from the tank mentioned in the original post. if so then i only used about 20 gallons for that week mentioned. my fuel gauge reads about 1/4 tank lower than it actually is so its a guess at best

Two things come to mind. Is the space between the hull and floor(deck) foam in place? I had an an older Formula. I pulled the deck. The foam was saturated. The rebuild was decades ago but I'll bet the additional weight topped 500 to 700 pounds. Secondly, are you reaching max RPM or slightly above with your current prop?

At 3200 rpm, you should only be burning about 9-10 gallons per hour with that engine. I would verify your tach also, maybe youre turning more rpm than you think. My 1991 250da ran 25 mph at 3700-3800 rpm turning a 15.25x15 prop. Also verify your wot rpm and speed. This will tell you everything you need to know about how the boat is running.

my top speed is about 33-34 MPH GPS verified at about 4000 RPM with a 15.25x17 prop so i am low on RPM. my manual says top speed should be about 32 MPH and max RPM i think is supposed to be 4200-4400 so i seem to be getting the speed. i think my manual calls for a 15x15 prop from the factory. and i would like to verify my RPM as well. being 30 years old it may be off a little. not sure about the foam but as far as i know it is dry but no way to verify is there?

I had a 95 Campion 25ft pocket cruiser very similar to yours (lighter than your 250 I think) with a 5.7 Mercruiser with carb . I had a fuel flow meter. At cruise maybe 28 to 30 mph, it burned 10 to 10.5 gph, right around 2.1 mpg (2.5 per Canadian gallon). So maybe you need to buy Canadian gas :smt043

Creekwood said:

I had a 95 Campion 25ft pocket cruiser very similar to yours (lighter than your 250 I think) with a 5.7 Mercruiser with carb . I had a fuel flow meter. At cruise maybe 28 to 30 mph, it burned 10 to 10.5 gph, right around 2.1 mpg (2.5 per Canadian gallon). So maybe you need to buy Canadian gas :smt043

Click to expand...

My Regal 2465 was slightly less (8-10 gph against the current / 5-6 with) with a Volvo 5.0L, 220HP. Again, I cannot speak highly enough of the Piranha composite 4 blade prop and their customer service. It paid for itself in 2 seasons.

Creekwood... Those are Canadian miles so they don't really count except in Canada. You're really getting less MPG than a carrier. Check you fuel bills... No....that won't work. You pay those with Canadian money. I give up!!:smt043

To the OP. To find out if there is water in the glass, whack the hull with a rubber mallet. It should thud. If there is a surveyor around, he/she could do it in a couple of minutes and tell you. Beyond that see if you can rent an IR camera or a moisture meter. UNLESS the boat has been trailered, garage kept and covered there is a distince possibility of moisture. Check the stringers.

i did hit the transom with a mallet before i bought it. nothing odd sounding. if i remember correctly it was kept on a lift and it was stored indoors in the winter. i bought it from the original owner. i currently keep it in underground storage in the winter but it stays in the water all summer for the last 2 years but i did re-seal all transom holes with 3M 4200 before putting it in the water this past summer. i always keep the camper top on it when i am not there. it has a mooring cover too but i don't use that. i believe it was slipped under cover before i got it but would have to check with the PO to be sure.