115 Merc 4-stroke Nitro 189 fish and ski

Okiedust

Recruit
Joined
Feb 15, 2009
Messages
5
I recently purchased a 2007 Nitro 189 Fish and Ski with a 2006 Mercury 115hp
4-stroke. The boat and motor is in excellent condition appearing like new in all areas. Boat length is 19'5. It has a Vengeance 13&1/8 x 16 SS prop. During my first and only test run we had 3 adults (485lb) and no gear. The hole shot was great but with WOT we hit 7000rpm with a top speed of 43mph on choppy water. This prop will probably be good for a boat full of people and pulling a skier but my main goal is mid-range crusing with occasional top end. The Nitro stats stated that this boat with a 115hp merc had a top end of 49. I wonder what prop they were using for their tests? From what I'm reading, I'm leaning toward a 3 blade 13.5" x 20 prop. I have no experience here so any help will be appreciated.
Thanks,
LarryD
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: 115 Merc 4-stroke Nitro 189 fish and ski

First I think I'd have the tach verified. It's highly unlikely the motor was really turning 7000. If it is accurate your new prop will be in the 23" range.
 

xxturbowesxx

Chief Petty Officer
Joined
Apr 20, 2008
Messages
491
Re: 115 Merc 4-stroke Nitro 189 fish and ski

I recently purchased a 2007 Nitro 189 Fish and Ski with a 2006 Mercury 115hp
4-stroke. The boat and motor is in excellent condition appearing like new in all areas. Boat length is 19'5. It has a Vengeance 13&1/8 x 16 SS prop. During my first and only test run we had 3 adults (485lb) and no gear. The hole shot was great but with WOT we hit 7000rpm with a top speed of 43mph on choppy water. This prop will probably be good for a boat full of people and pulling a skier but my main goal is mid-range crusing with occasional top end. The Nitro stats stated that this boat with a 115hp merc had a top end of 49. I wonder what prop they were using for their tests? From what I'm reading, I'm leaning toward a 3 blade 13.5" x 20 prop. I have no experience here so any help will be appreciated.
Thanks,
LarryD

A 16pitch seems very underpropped for that boat.. I would say 19p or 21p.. i have had 2 fish n ski boats similar to yours i had a 17.5 procraft with a merc 150 that had a 21p and now I have a winner 18.5 with a 150 that has a 23p and while it will run 65mph with that prop Im guessing when summer comes around and I start towning skiers I will have to go back to a 21p. Take it back to a dealer or a good prop shop and they will let you test until you find the right one for you.
 
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