Gallons / Hour Discussion

[zeehag]

capttman--my boat weighs in at 28000pounds displ. is spozed to be 34000..she is light.

[sailorboy1]

Originally Posted by virginia boy

I think something must be seriously wrong with mine. I have a Yanmar 20ymsomething with roughly 1000 hours on it, I run it at 26-2800 rpms and I use 1.5 gallons/ hour! It runs great just burns a lot of fuel. Could a feathering prop cause such a large increase in fuel consumption?

My last boat would do the same. But at 1500 rpm it would use .65 gph. Speed has it's price, slow down some.

[Cheechako]

My CT/Tanton 44 with Perkins 4-108 burned about .6 -.65 gal per hour at 8 knots.
My lagoon 42 with two 3gm30 Yanmars burned less than .5 gal per hour per engine.
Passport 47 with Nanni/Mercedes 85 Hp burned a little over 3/4 gallon an hour.

All boats had Max props....

[unbusted67]

Originally Posted by virginia boy

I think something must be seriously wrong with mine. I have a Yanmar 20ymsomething with roughly 1000 hours on it, I run it at 26-2800 rpms and I use 1.5 gallons/ hour! It runs great just burns a lot of fuel. Could a feathering prop cause such a large increase in fuel consumption?

26 to 2800 rpms is a high rpm. You might want to have a look at your engine manual to see what your optimal rpms should be. Also some of those Yanmar 20somethings are getting a tad long in the tooth, maybe you are having injector issues? Don't take my word for it though I am no expert.

[Cheechako]

Originally Posted by virginia boy

I think something must be seriously wrong with mine. I have a Yanmar 20ymsomething with roughly 1000 hours on it, I run it at 26-2800 rpms and I use 1.5 gallons/ hour! It runs great just burns a lot of fuel. Could a feathering prop cause such a large increase in fuel consumption?

That is way too much. Not sure which one you have, but most Yanmars are something like 3600 rpm upper limit. Reportedly that's what yanmar wants them run at... but then maybe they sell alot of parts that way!
How does your exhaust look?

[DRS]

.55 US GPH combined on 2 MD2030 Volvos at 2400 RPM and 7 knts. 38 foot cat at about 17000 pounds

[zeehag]

my yanmar 2qm20h is so beautifully fuel efficient--- make sure all you injectors are good and the elbow is good mebbe get a 600 hour overhaul. does wonders for stuff'n' stuff that stops working. i did that when i bought my ericson in 2004--yes, i still have it...

[DeepFrz]

A 2ym15 should use a little less than 2 liters/hr. at 2800 rpm according to Yanmar

A 3ym20 will burn about 2.75 liters/hr at 2800 rpm.

If you are really burning 1.5 gals. per hr something is wrong, or you have a different engine or you meant liters, not gals.

[Adelie]

Originally Posted by capttman

Heavy displacement boat 16 tonnes with 4-108 I burn about .75 gals an hour at 6 knots, if I have wind indefinite the tank never goes down haha

Indefinite, I don't think so. More like 20,000-40,000 mpg as the stuff evaporates.

[David M]

On a plane at 18 knots about 20 GPH.

[malbert73]

Yanmar 3YM30 on a 6.5 ton 33 foot sailboat. At 2600 RPM I get 6 knots and burn 0.5 GPH.

Engine has 500 hours and no oil burning whatsoever, and barely discolor the oil 1/2 way, or 50 hours, through the season. A smooth little machine...

[onestepcsy37]

i actually keep track of this in my engine log.

perkins 4-108 in a 20K lb full keel gets .8 gph running at mostly 1700 rpm and 5.5 knots.

[hogfighter]

Originally Posted by virginia boy

I think something must be seriously wrong with mine. I have a Yanmar 20ymsomething with roughly 1000 hours on it, I run it at 26-2800 rpms and I use 1.5 gallons/ hour! It runs great just burns a lot of fuel. Could a feathering prop cause such a large increase in fuel consumption?

My previous sailing vessel was a 32' Morgan with a Yanmar 20ysomething, and at 80% rpm I would burn about .5gph, achieving around 5.5kts. When I would push her hard, I'd gain 1/2 knot and burn well over 1 gph! Try backing off just a touch, I think you may be surprised at the newfound fuel efficiency. Let me know if that helps....

[taildragerdrive]

My Universal M35 gets .8 gph at 1800rpm, MaxProp boat weight 18000# about 5 kts. Recently did a short trip at 2200 rpm, 6kts and had much higher consumption but was not able to calculate consumption, estimate over 1 gph.

[nes]

I have a Hunter 326 with a Yanmar 18 hp 2 cyl. (probably a 2ymsomething). Per the manual, 3400 max for an hour and 3200 continuous, no perceivable difference in speed of the boat from 3000 to 3200, so my max is 3000 rpm boat speed ~5.5 kn. Approximate fuel consumption is .4 gals per hour.