Propeller Interchangeability

[sec56]

I had to replace my 1999 175hp Evinrude with a 2005 200hp (3.0l) Mercury Optimax. The company which rebuilt the Optimax sold me a 15 x 19 prop with the Flo-Torq hub. They also told me my 15 spline prop from my Evinrude would fit the Optimax, so I kept the prop from my Evinrude for a spare. The 15 x 19 prop at W.O.T allows me to reach the low end of the RPM range for w.o.t. My primary cruising rpms are 4000 to 4200. My boat is a Crestliner Eagle 2360 SST. I was going to put the prop form my Evinrude which is 15 x 17 on the Mercury to let the Mercury run a little higher rpm's but found out quickly that it doesn't fit Mercury's front thrust washer that current prop fits on. The prop from my Evinrude, the hub is pressed rather than being a Flo-Torq hub. My 1st question is can I use a prop with a pressed hub on the Mercury Optimax? Can I get the proper forward thrust washer the fit the prop from my Evinrude to the Mercury output shaft? Both props are stainless steel. The Mercury prop is a Mirage Plus and the prop I don't know who the manufacturer is on the prop I kept from my Evinrude. Any answers regarding interchangeability would be appreciated.

 

[QBhoy]

Hi. In my opinion, a mirage is a hell of a big heavy and huge diameter thing for anything other than a big block and bravo drive to turn. Even on them…I’m not a fan and since their era, there are since much better props at doing what they were meant for initially.
You’d be better off with a more conventional diameter or prop, if he sure. Most 19” would be about 14” diameter. There isn’t much to go wrong with, using the old tried a tested laser 2, on most applications. Again. These have been superseded and bettered recently, but you get my point. Pound for pound or bang for buck…ain’t much better.
But…can also suggest that the more recent tempest plus prop…is an amazing thing for things like your set up. Has the best bits from a laser 2…but the momentum of the bigger props for efficiency and cruising well.

 

[sec56]

In an article I read, the Tempest Plus props are cupped. Although my Mirage prop looks like it may be slightly cupped too, but I'm not totally sure. I ran into the cupped problem with the Evinrude that used to be on my boat. The cupping cost me rpms and was aluminum. I bought a used stainless-steel prop at the same diameter and pitch without the cupping which let the motor reach max rpms at wot. What other brands/models' of stainless-steel props would you suggest without any cupping out side of the Mercury brand or is your preference sticking with Mercury brand props?

 

[sec56]

If needed, my boat is aluminum, weighs in empty at 2300lbs, carries a maximum of 83 gallons of gas (2 tanks), approximately 600lbs for passengers, and probably another 500 to 600lbs in gear. Boat length is recorded as 23' 4" and has 102" beam. The Mirage prop is 15 1/4 x 19.

 

[Texasmark]

Cupping is said to add 1" to the pitch of the prop, obviously putting more load on the engine. Cupping is necessary for high trim angles where the tip of the blades are close to the surface.....gives you grip where otherwise you might have a blowout and loose speed rather than gain. My 2c.

 

[Chris1956]

You should be able to use the OMC prop on your Merc. You will need to find a thrust washer that fits. I used a Merc V6 prop on my Johnny 150HPV6, without issue. I had to drill out 1/2 of the splines, because the Johnny's propshaft splines are a lot shorter than the Merc's I think I ground down the taper on the Merc thrust washer to fit properly on the Johnny's propshaft.

It doesn't matter if the prop hub is pressed in or modular.