4 blade prop vs 3 blade prop to pad measurement

[okskeetertzx190]

In general do 4 blade props need to be higher on the jack plate? Lower on the jack plate? Or the same height when switching from a 3 blade to a 4 blade. The two props I would be comparing are a 25 t2 and a 25 RX4. Thanks for any advice.

[Pulsare2020]

Someone with experience with those two props will hopefully reply. I have found not a hard fast rule that applies to all props. They generally tell you to run 4 blades higher, especially larger diameter 4 blades like the Bravo types. My two main props are a Bravo FS and a ProMax. Both are 4 blades, and the ProMax is more than 1/2" less in diameter, but has more cup and rake, and I can run it at least 1/2" higher than the Bravo FS. The slip on my Bravo FS increases after a certain height, but the ProMax will run higher before it slips. At one time I also had a 3 blade Solas Scorpion which is the same diameter as a Bravo FS, but more similar to the Yamaha 3 blade props. That 3 blade had a lot of rake and it would run as high or higher than my ProMax. I think all that will also change with the weight of the boat and torque of the engine. So what worked on mine might not work the same on another boat.

[bentzboatwhisperer]

@okskeetertzx190 start off running the RX4 at the same height as the T2. You are most likely going have to raise it maybe try 2 dots at a time that way you can always go back down 1 dot for fine tuning.

[okskeetertzx190]

Thanks. I started with one dot up. Mine was at 8. I am at 9 now. Gonna try to see how it does this weekend or Monday.

[bentzboatwhisperer]

That is whats up, cant wait to hear back.