Gas friendly hp size

[user 20022]

I know it's not a realistic thought, but i figured I'd ask what's the normal consumption of outboards between 25 and 40? What size tank should I put in my tin for a day of fun.

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[mdduby]

I get about 6 miles to the gallon with a Johnson 40hp on a 15.5 bass boat that's running at 4800 rpm.

 

[user 20022]

What speed would you say your going at that rpm?

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[mdduby]

With 2 persons and fully loaded it runs 25 to 28 miles an hour. This is a fiberglass boat and is pretty heavy.

 

[user 20022]

Good deal! Thanks! I'm anxious to hear what everyone has to say. I am thinking a 30 to 40hp May be the solution to power my tin.

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[PATRIOT]

Good deal! Thanks! I'm anxious to hear what everyone has to say. I am thinking a 30 to 40hp May be the solution to power my tin.

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2-stroke or 4-stroke?

 

[user 20022]

2 stroke. At this time.

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[lckstckn2smknbrls]

The rule of thumb is a 10hp motor will burn 1 gal of fuel per hour a WOT. a 20hp motor 2 gals, a 25hp motor 2.5 gallons.

 

[Skiffing]

I get 7.5 miles / gallon + at cruise 4800 rpm 23 mph with a 40hp Merc 4stroke on a 16' welded MonArc. 2 people and gear - total weight ~ 1,300

 

[user 20022]

6-7 mpg doesn't sound bad

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[DaleH]

One rule of thumb is that an OB of about 75-80% of the hull maximum rated horsepower will give the best fuel efficiency.

To back this up, there are some boat tests I've seen from Bob Stearns, a noted marine/boating author. He tested the same boat/same hull with a 90, 115 & 130 or 140hp motors and the 115hp was the most furl efficient.

It was only 3-4mph slower at WOT, but more impressive, was only 1mph slower at the most efficient cruise speed, yet yielded about 3/4 mpg better fuel efficiency.

 

[user 20022]

That's really interesting DaleH. Thanks for the info.

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[hankthecrank]

Im running a Evin 20 hp modified to 30hp on a 16x48 tin, at WOT 28mph im getting 6mpg.

 

[user 20022]

Im running a Evin 20 hp modified to 30hp on a 16x48 tin, at WOT 28mph im getting 6mpg.

That's really cool! What year Evin do you have?

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[RiverBottomOutdoors]

I had a yammy 25 4 stroke on a 1448 and could ride for days on 6 gallons.

 

[user 20022]

I had a yammy 25 4 stroke on a 1448 and could ride for days on 6 gallons.

What year was that motor? That sounds awesome. My tin is pretty wide. I'm not sure how that will affect the speed though. Thanks

Im running a Evin 20 hp modified to 30hp on a 16x48 tin, at WOT 28mph im getting 6mpg.

That's really cool! What year Evin do you have?

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[RiverBottomOutdoors]

I think it was a 2011 model.

 

[user 20022]

Thanks man. I'll have to save up for one of those. I bet they are pretty pricey.

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[hankthecrank]

Texas Prowler, its an 89 Evinrude tracker motor, I opened up the intake and put a 30hp carb on. I've seen 29mph on my gps.

 

[user 20022]

Dude that is freakin cool. I'm impressed. Most wouldn't attempt modding a motor. I'm up for something like that if I am presented the same situation.

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