# 2000 Johnson 25hp (2 stroke) fuel consumption



## Cricket Chunker (Mar 17, 2008)

Ok,  here is a question for all you who have expierance with 25hp 2 cycle outboards.

I recently purchased a used 17' alumnimum bass type layout Lowe with a 25hp Johnson (2000 model).

The guy who had it before me had two 6 gallon tanks in the rear.  I have not had it out yet, and I'm wanting to put in a 24v trolling motor as an upgrade to the 12v on it now.  So I'm looking at loosing one of the tanks to make battery space.  My concern is why did he have 2 of them in the first place?

How much fuel does a 2 stroke 25hp generally use?  Or how far should I expect 3 gallons to get me (3 gallons out and 3 gallons back to dock)?

Any thoughts?

And a follow up question....  

I'm looking at a 80# MinnKota 24v (digital model) and will 2 of the group 29 MarineMaxx batteries in series for 24v give me all day power with a 80# trolling motor?


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## seaweaver (Mar 17, 2008)

Well it ain't no 4 stroke but it should get reasonable fuel economy..what that interprets into is variable. Its harder to float in fresh water than salt. How long/wide  the plane surface and over all weight will play a big part.
The best bet is to run it.
I just put a 50hp on a 13 whaler. It's working at what I would guess in the lower third of it's power range.
W/a light boat  I can do 38mph.
W/ a 2nd man, beer, and two 200 hogs I still can do 34.
I think you are going to be working the top third of your power range. A tank(42lbs) less a new batt(60lb) is about a 10lb gain(less the troller) . If you can get that weight towards the center of the boat you will be much better off. I would guess you have a 14.5 planing surface which is good.
I don't know if you have ever used a Dolfin but I put them on every motor I own(25,40,50,115) except the 8hp. The amount of lift is great which really helps you maintain lower plane speed and thus fuel savings. Getting on a plane is much quicker which is another fuel saving effect and if you are forced to put that battery in the back...your gonna need it as I assume it's a tiller steer which means your wight too.
My 25hp was on a 14' plywood batau that was a rocket...fuel was cheep...so I never noticed the true consumption. we had a nearly 4' wide flat bottom so it was a skate and seemed to run forever on 6 gal.
Fill it and run it..and try to keep the weight in the middle.
cw


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## Cricket Chunker (Mar 17, 2008)

It already has a dolphin stingray installed.  It is not a tiller, but a remote side console model (it's layed out like an aluminum bass boat with front and rear decks, pedestal seats side console, and 28 gal livewell opposite the console).  It's all aluminum so it is a very light boat for the size.  It's a 17x56 bottom if that helps.

I'm not overly concerned about top end speed, as that will be what it is.  It's got a 10x13 prop on it and there is a more aggressive model available for more speed (but is there a drawback to that as well? Remember I'm new at this).  If I can manage the mid 20's or better I'm happy on speed

I was just wondering does a 25hp 2 stroke use that much fuel that it needed the 2nd tank.  For me a long trip would be putting in at Highland Marina on West Point and heading down to the lower end of the lake for hybrids and maybe ending the evening tied up under the 109 bridge fishing for crappie.

Keep in mind this is my first gas powered boat so I have no prior reference.

Thanks

Here are a few photos to give you an idea of what the boat actually is.


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## stevetarget (Mar 20, 2008)

nice looking boat. Boats always get less mileage than you think. take both tanks until you get a feel for how far you can travel. A stiff headwind can cut your gas mileage, extra weight from all the big fish you catch might cut you a little low on fuel.


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## Doyle (Mar 21, 2008)

Years ago,I had one of those fuel flow computers on a boat I owned that gave a constant MPG readout.   I found that just a few hundred RPM above or below your ideal cruise speed and your mileage would go down - sometimes by a lot.


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## Twenty five ought six (Mar 21, 2008)

Well, I had one of those motors for years, and 12 gallons of gas will run you all day, and then some.

I had two gas tanks, and here's the reason --you mix gas in units of 6 gallons.  With two tanks, it's easier to mix (no math) and you can run one dry, and always have fresh gas.

Rule of thumb for two cycles is that a motor at WOT will use one gallon of gas per ten HP per hour -- so a 25 would use 2.5 gallons per hour, or almost 3 hours of running at WOT on a 6 gallon tank.  This formula was consistent with my experience.  The less time that you spend rinning at WOT the less gas you will use.  An hour run is a long time in a flat bottom boat.

I used to fish and hunt on the Altamaha where I would have some long runs.

Mid to low 20's is about what you will get.  I changed props, and there's just not a lot of difference.  Best thing I did was put on a SS prop, but that's just because of all the sandbars.


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## Cricket Chunker (Mar 21, 2008)

Thanks for the info.

I would like to loose one of the tanks so I can put in a 3rd battery (24v for trolling motor, seperate for other electronics & starting Johnson).

There is only so much space back there and it already has two of the group 29 MarineMaxx batteries.  To add a 3rd, one tank must go (or set on the deck).


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## bassboy1 (Mar 22, 2008)

If it were me, I would lose the tank, and add the battery.


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## Cricket Chunker (Mar 23, 2008)

I think I found a solution.  I measured the space I have back there today.

I can put 3 of the MarineMaxx group 29's from Wallyworld on one side of the rear compartment (already have 2 that hold excellent charge and are same age).  I can then put a 12 gallon tank on the other side.  I found a 12 gallon tank that will fit with room to spare.

Batteries will outweigh the 12g tank a little, but I'll put the batteries on the side opposite where I sit  (I'm a big guy ok).  With them that close to the centerline, I don't think it will matter anyway.

That way I get the best of both worlds. 3 batteries and tons of fuel for the 25hp.


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