prop for 28 spl on 25' pontoon

[gelston5585]

I picked up a 1991 crest 25' toon with a johnson 28 spl. It looks like the prop on it is a standard 12 pitch. I don't have a tach, but from what i'm reading I should probably go lower. Especially since most weekends I will have my wife and kids on board.
I found a 9 1/4 x 7, which I believe is the lowest pitch for that motor. Should I buy it while it's available or try a 9x9" first?

 

[ahicks]

You don't plan on being in a hurry with it do you? Have you tried the prop that came with it to see if it will work for you?

 

[gelston5585]

I know i'm slow. I'm definitely not in a hurry. I've gone across the lake a couple times with it.
I just want the best option for small motor/big boat and to keep the motor as happy as possible.

 

[Scott Danforth]

You just bought a 28 year old boat and motor that has been running fine for 28 years.

Just go boating

 

[gelston5585]

True. I could just keep it on there. I know it's not the original prop, but I'm not sure when the previous owner replaced it.

 

[ahicks]

Let's say you pursue your interest to get it done "right". You'll need a tach for starters - no "if" to it. Then you go do your sea trials, get a good tach reading, and purchase the perfect prop, one that let's the engine turn it's rated rpms at wide pen throttle.

On your next sea trial, how much difference do you think you may notice? My experience tells me that the only difference you're going to see is on the tach you installed, and then, at your normal cruise speeds, very little if any difference. The motor isn't going to care about the money, and trouble you have invested in that new prop, unless you're running it at wide open, or nearly wide open frequently. Your call!