How Much Fuel Did We Just Burn?

The costs of operating a sailboat vs a powerboat always stun me.  I went for a 45 minute ride in my slip-neighbor’s 35′ sport fisher this morning, because he was demonstrating an engine performance problem for some of the other boat owners.

This is not his boat, but similar in size.

This is not his boat, but similar in size.

10 minutes of slow motoring got us into the open bay, then it was oscillating between wide open throttle and modest cruising speed for the next half hour, then a sedate idle back to the slip in Rockhold Creek.  I have no idea how much fuel he burned, but I know that his boat is powered with two 350 hp inboard gas monsters (that sound absolutely great, by the way – you gotta love that roar for the raw power it represents).  And I have to admit that it was really fun to be way up in the air on the fly bridge going slowly and going fast.  Really, it pushed the fun meter all the way over to the right. Kind of cool, too, to be at eye-level with the osprey nests.

Back at the slip, he adroitly parked the boat stern-first (I was impressed) and we tied up.  But again, how much fuel did we burn. . . ?  5 gallons?  8 gallons?  What would a 100 mile trip to Deltaville Virginia cost in fuel?  Again, not sure about that, but I do know that my slow, low-powered sailboat burns a gallon of diesel every 2.75 hours at cruising speed.  And I know I can afford that!


  1. I’d expect a lot of gas. I have a 2008 115hp 4 stroke Yamaha on our power boat and the best I can get is a bit over 6mpg at @ 4000 rpm which in smooth water speeds us along at about 25mph. I get in the 5mpg range going @ 5mph. From that up until plane it’s worse. And that’s a whole lot better than my old two stroke got me.
    So 6mpg @ $3.30/gal now for the “cheap” ethanol variety and not at a marina would cost us $.55/mile, not including the cost of marine Stabil addition or my effort to fill and deliver the gas to the boat. So at 25mph it takes a bit over 4 gallons per hour and costs us $13.75/hour to operate in the best case. Twin 350s have to burn much more than our puny 115hp. I expect it’s easily $3.00 a mile for his boat. Too rich for me. Glad someone has the money so I can watch though. Love a diesel. If your diesel costs $4.00/gal then it costs you $1.45/hour to operate instead of my $13.75/hour or his, maybe, $75.00/hour, or more. So if you “only” went 7 miles in an hour your operating cost is $0.21/mile. I like the trade off. And you can pass us by under sail when our tanks run dry.

    • Thanks for crunching the numbers, Greg. $75/hour. . . wow.
      I figure I can get close to 15 mpg/diesel (that’s nautical miles). I’ve had cars that didn’t get milage that good!

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