I’m trying to get a handle on what kind of range I probably have in my Henry O. It has a 1995 Johnson 88SPL (basically the same as the 90HP) and a 42 gallon tank. The Henry O has a pretty deep running hull and should use more fuel than shallower hulls. I see mpg ratings for some boat/motor combinations ranging from 1 mpg to 7.5.
I could fill it up, spend a few hours running the thing at 3800 rpms, and go back and fill it back up to see how much it burned. Track the path w/ the GPS and do the math. But, I never run the motor on a plane the entire time I’m out. There’s plenty of trolling and/or idling around. So, it is difficult to estimate how much range the thing has on a plane.
For current motors, I can go to places like http://www.scoutboats.com/models/pdfs/SCT-175Dorado-F90TLRB.pdf for a pretty good idea of what the motor is doing.
I fear my motor is old enough that literature like that is long gone.
Anybody have any experience with the 90HP Johnson from that era and how much fuel it would burn on the back of a big 17’ boat? Should I expect 1 mpg? 3? 4? 4 would be surprising. 1 would be a little disappointing.
I should say that this is for general information, only. I would not plan a trip to the ledge based on such information…even as good as you guys are… not sure I should place quite that much faith in any guestimates 
17’ Henry O Hornet
w/ Johnson 88spl
OK, I’ll put a blindfold on and try it.
3800 rpm I bet will get you going about 25 mph and you’re probably burning 10 gph so 2.5 miles per gallon?
That’s my guess and that is only what it is. Now as for off and on the throttle and all that who knows. I bet that boat averages 2 miles per gallon on a normal day out on the water. Let me know how close I am.
Grady White 222
what kind of GPS you got? It should tell you how many miles you traveled and then just fill the tank back up and that should give you a rough estimate like you stated. Always err on the side of caution.
No one knows if YOU are THE village IDIOT or not until YOU open your mouth and speak!!!
I would not expect more than 2 mpg. Probably 2.5 at best cruise. I had a 115 Johnson on a 17’ Whaler Outrage and that’s what I got at best. I used to burn about 12.5 gallons in a day of inshore fishing. Now I have a larger Edgewater that weighs a good 1000 pounds more with a 135 Optimax and burn about 7 gallons a day inshore. I haven’t seen many carbed 2 strokes boats that get near 3 or 4 mpg unless they are small and light like a flats boat.
Do what yourself suggested and track miles run and how much fuel you put in. I would just go out for the day and run it normally. It will still give you and good average of fuel burn.
Iain Pelto
Edgewater 185CC “Jumpin’ Bean II”
For about a buck and a half, you can get and install a Navman flow meter. This sweet little device will give a very accurate reading of rate of burn and remaining fuel. Well worth the investment.
GW 232GT Gulfstream
150Yam x 2
“3rd Day”
Gen. Chap.1 Vs.9-13
Thanks Guys.
hairball, that’s just what I was looking for… an estimate based on a fairly similar motor (same block, I think) with a fairly similar boat. I was thinking it should be around 2 to 2.5 mpg. With as much dead rise as my hull has, 'probably closer to 2 than 2.5. And, I realize these are guestimates. I will do something like a GPS track to get much better numbers before I make any trips that get anywhere close to my fuel range.
thanks
17’ Henry O Hornet
w/ Johnson 88spl
get a 6 gallon external tank and fill it up. run at whatever speed you usually run at. when you run out that is your mileage. no need to fill the big tank up all the way.
ft worry.
quote:
Originally posted by cordrayj1
get a 6 gallon external tank and fill it up. run at whatever speed you usually run at. when you run out that is your mileage. no need to fill the big tank up all the way.
ft worry.
Easiest way to do it. Done this on mine and a couple of friends.
one was a 17ft proline with a 88 spl similar draft and wt to yours he was 2mpg at 3800-4000. Mine a 1720 keywest w/90 yammy 2.2 at 3500
6-gallon can is a good idea.
And, thanks for a few more data points… especially a data point with an 88 spl.
17’ Henry O Hornet
w/ Johnson 88spl
Geez, I average over 2 mpg with my thirsty carbed 140, but I guess having a flat bottom helps me out a bunch. I’ve taken two big 60+ mile river rides in the last few years, neither of which used all of my 32 gal tank.
Baker
Old, beat up 17’ McKee
It is not really the size/horsepower of the engine that determines the fuel consumption. It is more a function of the power demand of the boat at given speed.
Iain Pelto
Edgewater 185CC “Jumpin’ Bean II”
I had a 17’ 96 HydraSport HydraSkiff w/96 90hp Johnson and I adveraged around 4mpg.
Bring plenty of Beer and ice.