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Fuel mileage

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david_r

Advanced Contributor
"ive got a question, probably

"ive got a question, probably been asked million times over, what kind of mileage should i be getting on 79'115? wot gets me bout 4-5 mpg, seems like a gas hawg to me. boat only 16.5' , 830#s dry then gear, motor, gas, and fishing buddy. doesnt seem under powered water spray well at back of boat and i mean ontop of the water. prop 13.?x19. any advice? adjusting carbs, cleaning carbs, little less on the hammer?"
 
"It is something called "

"It is something called " drag " caused by water. Try this ----put your truck on a level road, then put it up to 40MPH ---now put it in nuetral and let it coast. Measure how far you go. Now try the same with your boat.-----Now you may understand.It is the boat that uses the gas not the engine."
 
"gotcha. smaller fishing buddy

"gotcha. smaller fishing buddy lol
biggrin.gif
. thanks for your help."
 
"Just for comparison, my '

"Just for comparison, my '75 115 on an 18' trihull with one passenger and fishing gear (aprox 1800 lbs) running at a comfortable crusie speed of 30 mph (wot 40) with some idling gets about 3 mpg as calc by GPS distance and fuel used. It is tuned well."
 
"May I add, check your rpm&#39

"May I add, check your rpm's to see if that matches the manual listed range.

Also, there was an OMC bulletin to detune engines that were built in the leaded gas era. This procedure cost me some performance.

I would like to get 4-5 mpg!!!!!"
 
"Another point to remember tha

"Another point to remember that may save you some gas, is that if you reduce your throttle to about 75% of WOT, you will use about 25% less gas but only lose about 10% of your speed. Just a rule of thumb and will very a little for everyone, but 75% of WOT is considered the sweet spot on most motors."
 
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