23 pitch prop for rebuit Mercruiser 4.3

[Jgcrock99]

Looks like your prop is right in the parameters for the engine. You can check recommended propellers at the Prop Wizzard
https://turningpointpropellers.com/PROPWIZARD/ (working link below), but for this engine and similar boat it recommends either 19 pitch or 21 pitch with the right diameter. As for the nicks on the blades, if they are not too deep and the blades are not deformed, just use the file and take the nicks out, that is what the shops do.

Thank you, I used their prop wizard to get to the 4 blade hustler 19p. I was under the impression that if I have a towing propeller on for water sports and heavy loads I should reach the top of my rpm range if not exceed it under light load conditions? I thought raising the pitch decreased max rpms? I lowered pitch and my rpms went down and I was concerned about over straining the engine. I'm new to the process and I definitely don't want to cause any issues. Strange also, while testing the propeller I ended up with cavitation burn after only running for about two hours. I did ventilate once but only for about 2 seconds. Hull is clean so I'm not sure what would cause it and I didn't think it should be able to cause the prop to burn in such a short amount of time. Are there any brand preferences out there? Powertech? Michigan wheel? Quicksilver? Turning point? Thanks

 

[dlogvine]

Thank you, I used their prop wizard to get to the 4 blade hustler 19p. I was under the impression that if I have a towing propeller on for water sports and heavy loads I should reach the top of my rpm range if not exceed it under light load conditions? I thought raising the pitch decreased max rpms? I lowered pitch and my rpms went down and I was concerned about over straining the engine. I'm new to the process and I definitely don't want to cause any issues. Strange also, while testing the propeller I ended up with cavitation burn after only running for about two hours. I did ventilate once but only for about 2 seconds. Hull is clean so I'm not sure what would cause it and I didn't think it should be able to cause the prop to burn in such a short amount of time. Are there any brand preferences out there? Powertech? Michigan wheel? Quicksilver? Turning point? Thanks

I have not encountered any cavitation problems, but I use the stainless steel prop, it might be better withstanding cavitation. Or there might be a better design (mine is 19p quicksilver) that does not create a cavitational bubbles. Increasing the pitch should reduce the max rpms, since it means the engine must work harder and push the boat further on one rotation of the prop. This is what I think from the physics perspective, maybe there is something more to it that im not aware off. But from what I saw, if you trying to get higher speed, you chose a higher pitch prop (in your case 21 pitch), for higher load or towing, you chose lower pitch (19 pitch according to the prop recommendations). There are still slip factors and material from which the prop is made (later im not very sure how it does affect the rpms and top speed).

 

[Chris1956]

JG- that TP prop should be a good one for your application. 4500 RPM is fine for that 4.3, as it is not good to rev them up, IMO.

I would try it with the water sports you cited. I think it will be fine, as I had a similar boat/motor combo and a similar prop and pitch. My prop was a 21P SS Rapture, which is real close to the TP design.

I also get some cavitation burn on my 23"P TP hustler, however, it is on a 60+ MPH high performance speed boat. I would not expect your boat to have similar issues. Maybe you overtrim a bit? Just a guess.