Bertram 25

[MichaelVT]

I'm hoping someone can guide me to where I can find a calculator to determine what prop I should be using for my given engine and outdrives.
I have a 1966 Bertram Sportfish, repowered with 2,1996 3.0LX motors with 135HP each. I just replaced the Pre-Alpha outdrives with Alpha 1 Gen 2, 1.81 gear ratio.
Mercurymarine.com has a tool on their site but they don't have a pull down choice for the 1.81 ratio but they do for 2.0.
When I input my data for the boat, the recommended prop with the 2.0 ratio is a 3 blade 14 diameter, 23 pitch.
How can I translate that result into a 1.81 gear ratio?
Bonus question: What size and pitch could I use for a 4 blade aluminum prop from the above results?
The prop I'm looking for would be for general all around use.
Thanks.
Michael

 

[Sandy]

Here are a few you can try playing with ( Google):

https://www.vicprop.com/planing_size.php

https://www.marksmarineinc.com/choose-your-prop-with-the--prop-calculator

http://www.rbbi.com/folders/prop/propcalc.htm

http://legacy.qsprops.com/prop-selector/#

 

[pdecat]

After you mess with the prop calculators go to a good prop shop. they will usually let you try props until you are satisfied.

the actual weight of how you use the boat will be important. I suspect that salt or freshwater makes a difference as well.