Prop selection II

[JoeCrow]

I just bought a 2002 Merc, 125hp, 2 cycle motor for my 1986 Bayliner 19' cuddy
The new motor doesn't come with a prop
The boat ran fine with the old motor using a 12"x17p prop
Using Merc's prop selector, they suggest a 13"x23p prop for my boat and usage, fish and ski
Does this sound right?
Would the engine change cause a need to change from a 17p to 23p prop?
I'm just trying to figure out what prop to buy for the new motor

 

[Bondo]

Re: Prop selection II

Ayuh,.... What was the Old Motor,..??

Did you account for the lowerunit gear ratios,..??

 

[codertimt]

Re: Prop selection II

So, are you choosing "Fish and Ski" as the boat type when using the Merc prop selection tool? You need to choose "Runabout - Cuddy"...

When I ran the numbers, it guessed a 21" for overall performance and 19" for better accerlation.

I'm guessing you're probably coming from a mid 80's 125 Force? If that's the case, it would have had a 1.73:1 ratio versus the mercs 2.07:1. So you should definitely expect to be moving up in prop pitch. Whether the 19" or 21" would be better suited would only be a guess on our part...unless you happen to find someone with a similar setup. The closest thing I have for comparison is my Dad has a '98 115 Merc on a 17' Ranger Fish and Ski. It turns a 22" prop at 5200rpm. Given you are in a much larger boat, I would personally start with a 19" and go from there...but that's just a guess on my part...

I would really see if you could find a shop/store locally that would allow you to demo something to get a baseline...

Good luck.

 

[JoeCrow]

Re: Prop selection II

Thanks guys,
Your guess was dead on
it was powered by a 1986 Force 125
Great running motor, but it was a 20" shaft and I have a 25" transom
It gave me fits till thanks to everyone here that helped, we figured it out
So I went to a 2002 Merc 125
Thanks again