Replacing well used prop

[jd438]

Here is what I have.
Alumacraft Trophy 185 with a 1998 Mariner Optimax 135 hp.
I am running an alumimum Black Max 14.5 x19 prop.
Hole shot is great and I run about 41-42 mph at 5600 WOT with 2 or 3 in the boat. (I think WOT on this motor should be 5000-5600)
The original prop has seen better days. The previous owner nicked, dinged, and bent it some, so I know I am giving efficiency up.
I would like to put a stainless model on, and I found a decent deal on Tempest plus 14.625 x 19. I have run this through a prop selector, but I don't really know what I am giving up on the current prop. I would expect my WOT to go down some. How much?

 

[steelespike]

Re: Replacing well used prop

Is your speed by gps?
I can't speak to the Tempest but it appears your present slip is a little high at 16%.Just going to a new prop should improve your slip.
and speed.If slip ended up at 6% speed would be about 47.Thats disregarding any effects from the tempest.
It's difficult to estimate changes when going from al to al when you add in a ss prop it becomes unpredictable, at least for me
a Tempest expert may be able to predict better.
For instance Any new prop is likely to load the motor more but may get the boat up better allowing more speed and rpm.
making any rpm change a wash. It is safe to say that the tempest should provide across the board improvement.
How much is the question.

 

[sschefer]

Re: Replacing well used prop

Is your speed by gps?
I can't speak to the Tempest but it appears your present slip is a little high at 16%.Just going to a new prop should improve your slip.
and speed.If slip ended up at 6% speed would be about 47.Thats disregarding any effects from the tempest.
It's difficult to estimate changes when going from al to al when you add in a ss prop it becomes unpredictable, at least for me
a Tempest expert may be able to predict better.
For instance Any new prop is likely to load the motor more but may get the boat up better allowing more speed and rpm.
making any rpm change a wash. It is safe to say that the tempest should provide across the board improvement.
How much is the question.

Well said! I ran a 135 on a similar fish/ski and found that a 19p Silverado (SS) was just a little too much. I could no longer get the motor up to max RPM (5800). I dropped back to a 17p Silverado (SS) and it was a much better fit. I attributed it to the lack of flex and lower slip rate of the SS prop vs the Aluminum. The design wasn't all that much different both the prior Al prop and the Silverado were basic general pupose props.

 

[jd438]

Re: Replacing well used prop

The speed is on GPS, and is fairly consistent.
Tempest Plus is Mercury prop designed for bigger fishing boats.
It is supposed to have a high rake and bigger cup for lift and handling.