Boat fuel efficiency

Jim Sargent

Well-Known Member
Yesterday I had a chance to perform an interesting experiment. I have a Crestliner 1850 Fish Hawk with a Merc 200 main motor. I have added two after market items that add weight, a 15 hp. kicker and an 18 gallon auxiliary fuel tank installed when Dangling Rope Marina closed.
We left Wahweap at first light with both tanks full. Heading uplake on smooth water I was able to make the entire trip at peak effiiciency for my boat which is 4500 rpm and around 40 mph. Tom Pryor from AZ Marine actually spent a day fishing with me and helping me learn the ins and outs wlhen the boat was new so I am pretty confident that he helped determine the best speed and rpm for maximum fuel efficiency.
After fishing all day using only the electric trolling motor I switched from the main tank to the auliliary for the run home. The first part of the trip we had smooth water and ran from 46-50 miles per hour. Somewhere around Gunsight we found rough water and wake boats so I had to slow down to 24-30 mph for the remainder of the trip in.
When we fueled at the Maverick Station the main tank took 4.5 gallons and the auliliary tank took just over ten gallons. A fairly dramatic example of how important it is to be aware of your driving technique on Lake Powell.
 

Jim Sargent

Well-Known Member
Gem,
I have to admit I am not an expert. I think Tom Pryor was seeking the best overall combination of efficiency for the time it takes to get to the fishing spots and fuel usage. I have fished with him for years and know he has been doing this for a long time.
Jim
 

Jim Sargent

Well-Known Member
Gem,
Your question motivated me to do some online research. On good water at 4500 rpm and 40mph I get just over 5 miles per gallon. Looking at the Mercury website and some of the walleye chat rooms it appears that with my set up I would exceed 6 miles per gallon at 3500 rpm so you are absolutely correct.
Jim
 

Rainbowbridge

Escalante-Class Member
This is a great thread that brings so many interconnecting issues for us powerboaters.

Fuel, speed, weight, aux tanks, running time...........wakeboats.......😋

Gem brings up a very valid point that my first 'floscan' in 1984 proved beyond a doubt. On plane and a tad more gives best fuel economy......but won't get you where you wanna go fast. I actually moved that floscan to several different boats & motor combinations and the results were always interesting. Floscans are still manufactured, not too expensive.

For example, on an 18' Maxum with 120HP, running at 3200 RPM 28MPH burned 1/3+ less than running 4500RPM @ 42MPH

Even tho time was saved, MPG was substantially less.

But, fast is funner.....

:cool:
 

Ryan

Keeper of San Juan Secrets
Good info, but I don't think you can take any of it in a vacuum. You have to consider both MPG and GPH. As long as I have the capacity, I will happily run at a faster speed, and burn more fuel to get in a few more casts at the end of the day, and still make it back to camp before dark.
 

Rainbowbridge

Escalante-Class Member
Fuel burn is now built-in to newer (2004+) Mercury ECMs. You just need to add the Bluetooth module to send the data to your phone using the free VesselView Mobile app. The app will display GPH, MPG, distance until empty, etc. It's been a game changer on my fishing boat.


Wow, that would be a game changer!

Sent the vid to several Merc friends that did not know about it. Thanks!

Things have changed slightly since 1984......

:LOL:
 

Gem Morris

Escalante-Class Member
That is a great video Bart. My Yamaha has a diagnostic port like that but it has to be read with a laptop computer. I haven’t used/owned a laptop since 2005ish so I’ve never plugged in to it. I wonder if other boat manufacturers are implementing this kind of technology on an app?
 

Meatwagon

Keeper of San Juan Secrets
That is a great video Bart. My Yamaha has a diagnostic port like that but it has to be read with a laptop computer. I haven’t used/owned a laptop since 2005ish so I’ve never plugged in to it. I wonder if other boat manufacturers are implementing this kind of technology on an app?
My Etec has a diagnostic USB port as well, but I don't think there's a mobile app for it like mercury offers.
 

Meatwagon

Keeper of San Juan Secrets
Jim, I was hoping that you made a run to bullfrog marina to get a long range average 😉. Oh well it sounds like it's sipping the Dino juice on calm seas.
It also demonstrates how much water conditions as well as how a boat is loaded down can impact your fuel consumption. Thanks for sharing.
 

Edward Gerdemann

Well-Known Member
Yesterday I had a chance to perform an interesting experiment. I have a Crestliner 1850 Fish Hawk with a Merc 200 main motor. I have added two after market items that add weight, a 15 hp. kicker and an 18 gallon auxiliary fuel tank installed when Dangling Rope Marina closed.
We left Wahweap at first light with both tanks full. Heading uplake on smooth water I was able to make the entire trip at peak effiiciency for my boat which is 4500 rpm and around 40 mph. Tom Pryor from AZ Marine actually spent a day fishing with me and helping me learn the ins and outs wlhen the boat was new so I am pretty confident that he helped determine the best speed and rpm for maximum fuel efficiency.
After fishing all day using only the electric trolling motor I switched from the main tank to the auliliary for the run home. The first part of the trip we had smooth water and ran from 46-50 miles per hour. Somewhere around Gunsight we found rough water and wake boats so I had to slow down to 24-30 mph for the remainder of the trip in.
When we fueled at the Maverick Station the main tank took 4.5 gallons and the auliliary tank took just over ten gallons. A fairly dramatic example of how important it is to be aware of your driving technique on Lake Powell.
Wow Jim! I burned 17.8 gallons on our day out Wednesday! Your setup is ruining well.
 

VikingRanch

Active Member
This gives me context for how light the fishing boats are. Your efficiency is amazing!

We have a 240 sea ray underpowered with the 5.0 mercruiser, and generally a fair load of people camping gear and dogs. I experimented did some math and ended up around 12.5gph at 27mph, more or less 4000rpm, as the sweet spot for speed and consumption. So just over 2 mpg. We carry 114 gallons for 3 days, but that lets us go up the Escalante from Waweap, and have a solid reserve. We also can run the same speed even in the worst of the channel near Antelope, love that boat for Powell.
 

Erik

Member
This gives me context for how light the fishing boats are. Your efficiency is amazing!

We have a 240 sea ray underpowered with the 5.0 mercruiser, and generally a fair load of people camping gear and dogs. I experimented did some math and ended up around 12.5gph at 27mph, more or less 4000rpm, as the sweet spot for speed and consumption. So just over 2 mpg. We carry 114 gallons for 3 days, but that lets us go up the Escalante from Waweap, and have a solid reserve. We also can run the same speed even in the worst of the channel near Antelope, love that boat for Powell.
I'm very much in the same situation. 5mpg seems obscenely high compared to my situation.

I'm running a early 90's 23' Four Winns with a 5.8L (which also seems a little under powered for the weight of the boat). We also often run with a considerable amount of people and equipment. Before I fixed my trim/tilt I was getting about 2mpg. In the absence of Dangling Rope, fuel management is so much more important now when visiting mid-lake. I had the trim/tilt fixed and I'm now getting about 2.5mpg (assuming the lake is calm-ish) and try desperately to maximize efficiency. 3200rpm @ 27mph (loaded down)...which seems to be the sweet spot.

I carry 60gal in the main tank plus an additional 20gal on the back in cans. My last trip was 150miles in total and burned a little under 60gal. (~2.6mpg)

I'm curious Viking, what does your boat weight? I'm at 3700lbs (boat and engine) and we seriously struggle with hole-shot when initially headed out with all our stuff (6 people plus camping equipment ***obviously a lot of weight***). I have to ask people to move forward to the bow to hold it down such that we can get on a plane.... and we still drag for some time before finally coming up onto a step. I wish I had a better strategy.
 

BartsPlace

Moderator
Staff member
I'm very much in the same situation. 5mpg seems obscenely high compared to my situation.

I'm running a early 90's 23' Four Winns with a 5.8L (which also seems a little under powered for the weight of the boat). We also often run with a considerable amount of people and equipment. Before I fixed my trim/tilt I was getting about 2mpg. In the absence of Dangling Rope, fuel management is so much more important now when visiting mid-lake. I had the trim/tilt fixed and I'm now getting about 2.5mpg (assuming the lake is calm-ish) and try desperately to maximize efficiency. 3200rpm @ 27mph (loaded down)...which seems to be the sweet spot.

I carry 60gal in the main tank plus an additional 20gal on the back in cans. My last trip was 150miles in total and burned a little under 60gal. (~2.6mpg)

I'm curious Viking, what does your boat weight? I'm at 3700lbs (boat and engine) and we seriously struggle with hole-shot when initially headed out with all our stuff (6 people plus camping equipment ***obviously a lot of weight***). I have to ask people to move forward to the bow to hold it down such that we can get on a plane.... and we still drag for some time before finally coming up onto a step. I wish I had a better strategy.

You might be over-propped for Lake Powell. If you're getting 27mph at 3200, you're pushing a fair amount of water with a 5.8L engine. That's closer to what you'd expect with an 8.1L. Maybe drop down a size? It would get you on plane faster and might make the sweet spot a little more gas efficient (though a bit slower).
 

VikingRanch

Active Member
I'm very much in the same situation. 5mpg seems obscenely high compared to my situation.

I'm running a early 90's 23' Four Winns with a 5.8L (which also seems a little under powered for the weight of the boat). We also often run with a considerable amount of people and equipment. Before I fixed my trim/tilt I was getting about 2mpg. In the absence of Dangling Rope, fuel management is so much more important now when visiting mid-lake. I had the trim/tilt fixed and I'm now getting about 2.5mpg (assuming the lake is calm-ish) and try desperately to maximize efficiency. 3200rpm @ 27mph (loaded down)...which seems to be the sweet spot.

I carry 60gal in the main tank plus an additional 20gal on the back in cans. My last trip was 150miles in total and burned a little under 60gal. (~2.6mpg)

I'm curious Viking, what does your boat weight? I'm at 3700lbs (boat and engine) and we seriously struggle with hole-shot when initially headed out with all our stuff (6 people plus camping equipment ***obviously a lot of weight***). I have to ask people to move forward to the bow to hold it down such that we can get on a plane.... and we still drag for some time before finally coming up onto a step. I wish I had a better strategy.
Barts on it. We weight about 6000 without all the gear and people, it’s a heavy boat, small bathroom, water system, etc., On the Bravo3 drive I’m down to a 20pitch 4 x 4 prop set from the stock 22 pitch. Made a big difference in getting on plane, but did reduce top speed. We cruise at just under 30mph, and wide open throttle gets us to 35 mph…. Low pitch sucks for speed, and the Bravo is great but not a high speed drive in general.

The best way to check your prop is to look up the maximum rpm rating on the engine, then see how close you are getting at wide open. With the 22 pitch loaded I was at 3900 and very challenging to get on plane. With the 20 pitch I’m up to 4500. Target for the motor is 5000, so I’m still a little over propped. I’m just not willing to give up any more speed, and am looking towards swapping to a 383 stroker and maybe a 24 pitch prop set. Being up there in October on glassy water has me craving more top speed.
 
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