Usable Fuel in 2023 R25?

[paulrice]

I am about to run a 200+ mile leg in my R25 (250HP Yamaha) from Hoppie's to Paducah, and there are no available fuel stops. The tech info in the R25 literature say the fuel tank is 99 gallons. I have only run the tank to 80 "gallons used" on the Yamaha fuel computer, but the fuel "gauge" was blinking on the last bar, indicating I was almost out of fuel. I will be taking extra fuel with me (even though I don't like the idea of storing gasoline on the boat). Do any R25 owners know the actual amount of usable fuel in the 99 gallon tank? I will literally be filling the tank to the top (visible) before starting.

 

[emtlibby]

Not based on fact, but based on how I think of it, given ullage and the fact that fuel needs to be picked up by a tube, I always aim to keep a 20 gallon reserve. That gives me about 80 gallons usable in my mind. I usually get 1.2-1.4 mpg. Based on that, I keep my legs to about 100 miles max. Bad weather will use more fuel. That said, if you slow boat around 6kts, you could stretch that since then you'll be getting 2 - 2.5mpg.

 

[paulrice]

Not based on fact, but based on how I think of it, given ullage and the fact that fuel needs to be picked up by a tube, I always aim to keep a 20 gallon reserve. That gives me about 80 gallons usable in my mind. I usually get 1.2-1.4 mpg. Based on that, I keep my legs to about 100 miles max. Bad weather will use more fuel. That said, if you slow boat around 6kts, you could stretch that since then you'll be getting 2 - 2.5mpg.

Thanks, I pretty much use the "80 gallons used is empty" rule too. But that is my cause of concern. If I use that rule, I will be very close to being out of fuel (even though I theoretically have 19 gallons left). I get between 1.9 and 2.1 mpg on a plane between 4200-4300 rpm. 2/3rds of the 200 miles will be down-current in the MS River which will help, but then I travel up-river on the OH for 40+ miles. I plan to bring 27.5 extra gallons of gas, and think I can make it. I unfortunately may be testing the "below 20 gallon in the tank is empty rule" we both use. I was hoping the factory (or someone) had run a full tank to the point of fuel starvation and noted how much fuel the Yamaha computer said they had used. Slowing the boat for extra mpg on the down-current leg is a good idea. Going up-river, the 2-3 knot current would be less % of total speed if I stayed on a plane.

 

[emtlibby]

The F250/300 really hates to be run dry, so you may be hard pressed to find someone who's run it to empty.

 

[Rode Trip]

Too many variables to get more accurate than 'save 15-20%'. How high above the tank bottom is the fuel suction tube? Which end of the tank is the suction tube and what is the boat's trim? What is the sea state? (you only need to suck air briefly if the tube is exposed due to sloshing fluid to shut down the engine, even if the stationary level is high enough.) How accurate is your fuel gauge? Are you going to be in a place you can just anchor and call a tow, or are you going to be in real trouble if you shut down suddenly and without warning? All variables that warrant leaving 20% in the tank, even if you could run it down to 5%.

 

[paulrice]

Too many variables to get more accurate than 'save 15-20%'. How high above the tank bottom is the fuel suction tube? Which end of the tank is the suction tube and what is the boat's trim? What is the sea state? (you only need to suck air briefly if the tube is exposed due to sloshing fluid to shut down the engine, even if the stationary level is high enough.) How accurate is your fuel gauge? Are you going to be in a place you can just anchor and call a tow, or are you going to be in real trouble if you shut down suddenly and without warning? All variables that warrant leaving 20% in the tank, even if you could run it down to 5%.

Thank you for the input, I am going to bring more gas! It makes it tough that there is a 200 mile stretch of the Great loop with no fuel.

 

[Akboaters]

We also learned that not every tank is the exact size the factory spec sheet states. For example, our R-23 has a 78 gallon tank. Our Garmin is set to think that max is 75 to give a small buffer.