Shaft length advice for Bass boat

[Joe Bush]

I have a 91 Nitro 2000DC bass boat and I'm thinking of putting on a Merc 2.5 with either a 25" or 30" shaft. What are your opinions with or without a jack plate?

 

[05GlastronSX]

Re: Shaft length advice for Bass boat

my guess would be a 25 inch shaft. im not sure but since its a bass boat, it most likly has a short transom and therefore it needs a shorter shaft or a longer shaft with a jack plate. id go shorter but don't quote me on that...

 

[rickdb1boat]

Re: Shaft length advice for Bass boat

What do you have on there now and how does it perform?

 

[Joe Bush]

Re: Shaft length advice for Bass boat

Its a 91 Johnson Faststrike 175. The speedo is not working, so I'm guessing about 65mph. I have only had it out once. Plan to check the speed with a gps.

 

[spego]

Re: Shaft length advice for Bass boat

Everything I can find looks as though your transom is a 20". I have a boat that is a 20" with a 25" motor on it and I would highly not recommend it to anyone. I bought the boat this way and to get any performance out of it I had to get a custom built jackplate for it....not even worth it. The motor sits way up high....which makes it look mean but just not worth the trouble. Buy a 20" if thats what your running now (which I would bet on it).

 

[Joe Bush]

Re: Shaft length advice for Bass boat

I measured to the bottom of the transom to the top and it looks like it is almost 22".

 

[spego]

Re: Shaft length advice for Bass boat

yeah 20" will work fine.

 

[walleyehed]

Re: Shaft length advice for Bass boat

Even with a 25" transom, I'd still go with a 20" on a jackplate. With low-water pick-ups, thats where a 25" would be anyway...

 

[Joe Bush]

Re: Shaft length advice for Bass boat

The motor I'm looking at is a 92 Merc 2.5. I don't what the HP is. Maybe somebody can tell me. (230 to 250)?? I thought it was a 25" but now know its a 20" shaft. The motor only has only 20 hours on it as it has been sitting since 1997. Hardly a scratch on it.

 

[JasonJ]

Re: Shaft length advice for Bass boat

If its a 92, it may be the "260", Which basically means it puts out around 260-ish horsepower. The downfall of the 260 is its charging system. It can barely keep up with all the accessories, trim, power jack plate, and you end up with an undercharged battery. The 260 also runs rougher at idle to mid-range. If it is the "280", it has a much improved charging system, engine idles and runs better in the low to mid range, and puts out roughly 280-ish horspower. You can tell the difference by popping the cowl off and looking at the top of the motor. A 280 will have an automotive style alternator driven by a belt, a 260 will have the under-flywheel type charging system.

The only reason I know this is because I just read about it in "Bass & Walleye Boats" magazine...:$

Another good thing about this motor is it weighs around 400 lbs. Show me any other big horsepower outboard that is that light...

 

[phatmanmike]

Re: Shaft length advice for Bass boat

first...bass boat equal 20" motors.

second, jasonj, why do you think its a 260 or a 280.

third, in that year, the motors above 200 hp have the 40 amp dual voltage regulated systems. my 1994 2.5l 200hp has the 40 amp dual reg system. but just today i swapped it out for the 16 am system from a 1989 150 hp with the lighter flywheel and 16 amp stator.

lighter flywheel = easier rpms
less magnetic force= easier rpms

 

[phatmanmike]

Re: Shaft length advice for Bass boat

first...bass boat equal 20" motors.usually

second, jasonj, why do you think its a 260 or a 280. if its a 2.5 it could be a 175, 200, 225 almost anything....

third, in that year, the motors above 200 hp have the 40 amp dual voltage regulated systems. under 200 had it as an option. my 1994 2.5L 200hp has the 40 amp dual reg system. but just today i swapped it out for the 16 amp system from a 1989 150 hp with the lighter flywheel and 16 amp stator.

lighter flywheel = easier rpms
less magnetic force= easier rpms