Yanmar fuel consumption

[ed c.]

The boat is a 1975 model with 315 Yanmars. 845 hours. 231 gal of diesel. The engines are 3 years old. Loaded up with about 200 lbs. of ice, 4 big guys and their equipment. Flat seas on the outbound to the Lindenkohl Canyon. Ran 86 miles at 26.5 knots. Trolled around just a little. Set for the night and fished for tuna and swords. Caught 8 tuna and gave 1 away to our dockmate as we had no more room. Average fish size was 70 lbs. Ran back to Cape May inlet at an average speed of 26.8 knots. Total trip was 190 miles, total fuel use was 149 gallons. I hope this helps
some of the guys and gals figure their use and compare. Good fishing to all.

[nic]

Thanks for posting that Ed, we are still trying to get exact figures for our 315s in a light(ish) boat.

I make that over 4lbs of fish per gallon, sounds like a great trip!

Nic

[ed c.]

Nic, i think the older models were heavier. Capt. Pat and UV would know. I forgot to add in the flats of bait we took to the canyon, figure another 130 lb.

[Bruce]

The older hulls were thicker, but not enough weight difference to increase fuel usage.

[Brewster Minton]

My lp6 315 burn the same amount loaded or with a half load at cruise. I do not see any differance on my flowscans.

[ZeroCavity]

Ed what was your RPM @ 26 knots ?

[JohnCranston]

What gear ratio and props are you guys running? Trying to get an idea of what to start with on my 315 repower. What's the best cruise speed with the best fuel burn? My bahia mar will be very light.

Thanks in advance.

[Tommy]

Since this thread is about Yanmar 315 fuel consumption and performance, I hope it is not considered hijacking to branch off to gears and wheels. I have the Yanmar 315s and have 2:1 gears swinging 20X23.5 four-blades.

3000 RPMs = 24.9 kts
3200 RPMs = 26.7 kts (my preferred cruise, 14-15 gph total)
3400 RPMs = 28.0 kts
3600 RPMs = 29.6 kts (maximum continuous operating RPM)
3800 RPMs = 31.5 kts
4000 RPMs = 33.0 kts (WOT)

Full fuel, full water, 2 people, moderate gear.

Tommy

[ed c.]

I was running around 3400 RPM's. I have a 2:1 gear with prop. sizes of 20x23.5. The boat does top off at about 33.5 knots.

[JohnCranston]

Thanks for the stats and info. Looks like a couple of miles to the gallon at cruise...very impressive.

[CHolgerson]

We have a light 1971 Bahia Mar with the 315 LPs and we have not burned more than 120 gallons on an overnight trip. We ran 192 nautical mile from Moriches Inlet NY to Indian River Inlet Delaware on 92 gallons. Last canyon day trip was to the poormans trolled all day and went home on 90 gallons. We are running 1.5:1 gears and are turning 18X20 DQX wheels. We are looking to take some prop out next season.

2800 = 25knts
3000= 26-27knts
3100 = 28knts
3850 = 35knts

All of these speeds are SOG on a Northstar 951. Hope this helps.

Chris

[JohnCranston]

Chris,

I'll admit, I'm a little confused. Trying to decide on what ratio to go with. Everyone tells me to go with 2 to 1, but it sounds like you're pretty happy with the 1.5 gears. If you were to do it all over again, would you stick with the same gears? Need some help, please.
My bahia mar will be very light.

Thanks.

[CHolgerson]

John,

We had our repower done by Dante Grover on Long Island, NY. We have been told by many that he is one of, if not the best repower center in the NorthEast. He has done many B31 repowers including some for the faithful (Charlie Johnson's "My 4 Girls"), . I fish alot with Brewster and he is also running 1.5:1 gears and his boat is a lot heavier than ours and his performance and fuel burn numbers are very close to ours. I have not been on a B31 with 2:1 gears so I can not really compare the two. On all of our canyon trips we always calculate total NAUTICAL miles and gallons burned and we always seem to burn 1.9 MPG. It seems that every trip we make regardless of load weather or length we always burn the same. We very rarely cruise faster than 28 knots and I do not think we have ever been able to run that fast to and fro on any single trip. We ran 26 knots for 7.5 hours on our trip to delaware and we averaged 2.04 MPG on that trip. My father likes the 2800-3000RPM range on these motors because that is where the motors makes most of its torque (550ft-lbs) and it also has a decent fuel burn (6-8GPH). We like the 1.5:1 gears :)

Chris

[JohnCranston]

Chris,

Man, that's what I needed! I'm sending my ZF 220a 1.23 gears back to them on Monday for a different ratio. Charging me a 15% re-stocking fee, but that's ok. Really appreciate it, Chris.