sea ray 197 prop question

old islander

Petty Officer 1st Class
Joined
Jan 27, 2013
Messages
302
Hello prop guru's
I just picked up a sea ray 197, 1978 model year 190hp merc 898 305 chevy V8. The boat came with an old well used and beat up stainless prop. I cant find any markings on it as to manufacturer or pitch. My question is, what prop would have come on this boat new as far as pitch goes? also, I intend to use this boat for trolling for salmon on lake Michigan so it will spend most of it's remaining life going 2.5MPH. I'm not looking for a ski or water sports prop. I'm looking for something that can get me 40MPH at 4000RPM. Any suggestions as to what pitch/diameter I should be looking for? I would like to go back to the aluminum prop for cost reasons. Is stainless a better bang for the buck?

Confused in Milwaukee
 

Bifflefan

Commander
Joined
May 27, 2009
Messages
2,933
For what you want, an aluminum prop is the ticket. No need for SS.
I would say a 17p should do you fine. You could go with a 19p also, but when you add trolling I think the 17p will be your best all around. A 16p 4 blade is good in my opinion as I think they add better slow speed handling on older boats, at least it did on mine and I could still do 40ish. It also trolled down very slow, slower than my GPS would register with any accuracy.
 

old islander

Petty Officer 1st Class
Joined
Jan 27, 2013
Messages
302
I like the 16p idea baffle fan, but what diameter would I use with the 16p 4 blade?
 

jestor68

Commander
Joined
Jun 12, 2012
Messages
2,308
Rather than guess:

A 1.5 gear ratio turning at 4000 engine rpm assuming a 10% slip at an actual 40 mph works out to a 17 pitch. But that doesn't mean your motor will do that, given it's age.

A 14.5 or 15 diameter would be appropriate.

4000 rpm as a target is a little low, since the rpm range is likely 4200-4600.

Regardless, a test run must be made with something in order to establish a base line.

The Mercury prop selector says that a 15 X 17 3 blade would be a good place to start.

Bear in mind that the selector assumes a new motor developing like new power.
 
Last edited:
Top