Long shaft motor - what qualifies?

[kenmiller476]

I want to put a larger horsepower motor on my 1989 Lowe pontoon. May be a 40, 50 or 60 horsepower; might be a Johnson or a Mercury. I understand from reading the posts that I must buy a long shaft motor, but I don't know what that means in terms of shaft length. Would a 20" shaft qualify or does it need to be a 22" or longer?
The transom on my boat has no adjustment available, it is fixed.
Thanks.

 

[Silvertip]

Re: Long shaft motor - what qualifies?

20 inch leg constitutes a long shaft motor. Mercury Big Foot (40/50/60 HP) are long shaft. Do not buy a standard (non-bigfoot motor for a pontoon). Whatever engine you end up with, mount it as low as it will go (resting on the transom bracket.)

 

[VaGent]

Re: Long shaft motor - what qualifies?

Why do you say NOT to put a non big foot Mercury on a pontoon boat? I am new to pontoons & am trying to learn everything I can. Is there something special about the big foot engine verses a non big foot? And exactly what is a big foot engine verses something like a Johnson 70 hp engine?

 

[Jeep Man]

Re: Long shaft motor - what qualifies?

Why do you say NOT to put a non big foot Mercury on a pontoon boat? I am new to pontoons & am trying to learn everything I can. Is there something special about the big foot engine verses a non big foot? And exactly what is a big foot engine verses something like a Johnson 70 hp engine?

Mercury Bigfoot is designed for pontoon boats and boats carrting heavier loads. they incorporate the gears of a larger engine which are 33% bigger in size. Designed for more thrust they have a much larger prop (14"). I suppose other manufacturers have an equivilent, but I cannot give any detail on those. Regular long shaft Mercs have a tendency to develop prop ventilation when underway.

 

[nhtrax]

Re: Long shaft motor - what qualifies?

Congrates on your new (to you) pontoon, I my self for the first time just bought a 98 crestliner 2080 it came with a 50 hp Evinrude the dealer put it on so I'm in trusting that this 20'' shaft is correct. From what i've learned doing the same you are doing (reshearching) the turbulance is much greater between the pontoons than a v hull so the shaft needs to be deeper for a better grab, I hope to find out soon but bought this alittle late in the season will take her out next year good luck engine shopping 40hp or 50hp anyways

 

[Silvertip]

Re: Long shaft motor - what qualifies?

There is not much of an issue with Johnson/Evinrude 20 inch engines because the gear ratios in these units favor the larger diameter props. Mercury on the other hand in their standard 40/50/60 non-Big Foot have small gear cases with 1.83:1 gear ratios. This requires small diameter props which do not work well in pontoon service because of the turbulent water. Some get away with it but if you have the choice, protect yourself and go Johnson/Evinrude, Merc Big Foot, or Yamaha Hi-Thrust. As for the power heads, there is no difference. And by all means, install a pontoon specific prop. For Merc Big Foot that's a 14" diameter x 11 pitch. Pontoon props have very large roundish blades that simply provide better thrust in both forward and reverse than a standard prop. This works to your advantage in reverse where docking maneuvers are a little more tricky than with a regular boat.

 

[kenmiller476]

Re: Long shaft motor - what qualifies?

Thanks. You guys are great and this forum is a terrific resource for those new to the pontoon world. I think I'm going to stick with Johnson/Evinrude motors with a shaft length of at least 20". I'm sure Mercury Bigfoot motors are great, but beyond my budget. Thanks again.
Ken