Mercury 175 prop help

[chelmke91]

I recently put a 2020 Mercury 175 Pro XS on my 2016 Bayliner 190 deck boat. I stopped by a local prop store and they gave me a prop that does not seem to be working out. I included the specs below. The boat will get on plane but there is a lot of cavitation during the hole shot. It will immediately rev up to about 5200 rpm and stay that way until it gets up to speed. Mercurys website claims that max rpm at WOT is 5400-6000 rpm. At WOT I'm hitting about 5600 rpm at 40mph. Any suggestions?

Prop specs:

Diameter: 14.25
Pitch: 19
Blades: 3
Metal: stainless steel

 

[WesNewell]

PCS holes too big? Prop not mounted flush? Prop make and model?

 

[chelmke91]

Prop is definitely mounted flush. Make is Power Tech Propellers. Part number is RAS3R19PMS275

 

[QBhoy]

Are the vents missing out the prop ? Sounds like pvs issue. I’d also strongly suspect that you are way way underpropped with a 19” on that set up. That is likely capable of close to or right on 60 mph with that engine. Is the hull rated for that power ?

 

[chelmke91]

The boat is definitely not made for speed. When I had the 115 on the boat I would get it to 37 at WOT with one person on it. I'm hoping to be around that speed with the boat loaded up now. There are no pvs holes on the prop. I put all of my information in to Mercurys prop calculator and it is saying I should be at 16 diameter and 13 pitch. Does that sound right?

 

[QBhoy]

The boat is definitely not made for speed. When I had the 115 on the boat I would get it to 37 at WOT with one person on it. I'm hoping to be around that speed with the boat loaded up now. There are no pvs holes on the prop. I put all of my information in to Mercurys prop calculator and it is saying I should be at 16 diameter and 13 pitch. Does that sound right?

No. That doesn’t sound right to me. Pretty sure there won’t be a prop of 13” pitch to suit that gearcase and even more unlikely it’s a 16” diameter and 13” pitch.

Just for clarification and being from the U.K. what is a deck boat ? If it’s what I think you should still have a fast boat with that engine on the back of it. Those motors are serious things and likely putting out closer to 200hp than 175hp. You should easily run a 19”...if not a 21” would be my thoughts. No way a 13” pitch is anywhere near correct for that set up. I’m 100% on that one.

 

[jimmbo]

A 13" Diameter would be too small for a V6