4 blade prop for 5.0l 19'

[ker]

I have a 19.5' bowrider with a merc 5.0l and alpha 1 drive, currently have a 14.5x19 3 blade prop, I want to switch over to a new 4 blade prop. Currently I get about 42mph @ 4500rpm trimmed out. I understand that when switching to a 4 blade you usually step down 1" in pitch to maintain the same rpm. However, 18p 4 blade props are not common. So either I stay with a 19p 4 blade and take the assumed 200rpm drop or step down to a 17p prop and jump up 200rpm @WOT. I don't ever run at WOT so there isn't a concern about over revving the motor. I spend most of the time cruising or towing (mostly tubes). I have only had the boat a few months now and this is going to be my first prop change, so any suggestions would be appreciated.

 

[Fox River Runner]

Re: 4 blade prop for 5.0l 19'

I have a 22 foot Azure deck boat with a Merc 5.0 mpi. It came with a 3 blade 19 pitch. It was a challenge to get up on plane with more then 2 adults on board. We put a 4 blade 18 pitch on. What a difference. The boat handles much better and was able to get on plane with 8 adults on board. I did drop a few mph's on the top end. But that's not a problem, I'm not really into racing. Check West Marine, or Boat US, I'm sure they have them in stock.

 

[642mx]

Re: 4 blade prop for 5.0l 19'

I have a 19.5' bowrider with a merc 5.0l and alpha 1 drive, currently have a 14.5x19 3 blade prop, I want to switch over to a new 4 blade prop. Currently I get about 42mph @ 4500rpm trimmed out. I understand that when switching to a 4 blade you usually step down 1" in pitch to maintain the same rpm. However, 18p 4 blade props are not common. So either I stay with a 19p 4 blade and take the assumed 200rpm drop or step down to a 17p prop and jump up 200rpm @WOT. I don't ever run at WOT so there isn't a concern about over revving the motor. I spend most of the time cruising or towing (mostly tubes). I have only had the boat a few months now and this is going to be my first prop change, so any suggestions would be appreciated.

Actually Hill Marine recommends a pitch for pitch transition. You might have a look at there site: http://www.hillmarine.com/MercruiserAlphaProps.html I've never ran one, but I know others who have, with good results.

 

[Bifflefan]

Re: 4 blade prop for 5.0l 19'

However, 18p 4 blade props are not common. So either I stay with a 19p 4 blade and take the assumed 200rpm drop or step down to a 17p prop and jump up 200rpm @WOT. I don't ever run at WOT so there isn't a concern about over revving the motor. I spend most of the time cruising or towing (mostly tubes).

18p 4 blades or very common.
4 blade props on iboats
Quicksilver and Michigan Wheel both make them and are available at almost any boat dealer.
I have a 16p and 18p both 4 blades and will never use a 3 blade again.
The Michigan wheel 4 blade Vortex is what i use and on iboats it is a very good price.

 

[bobmac010]

Re: 4 blade prop for 5.0l 19'

I have a ProPulse variable pitch prop on my boat-
http://www.propulse.se
You can get them locally, (at least on-line).
They vary about 4" pitch.
Check 'em out. The are not that expensive either.
4 blades- It makes for a smoother ride, and not as much "steer" or "walk" on takeoff.
They have more bite in the water for acceleration, but do typically decrease top speed by about 2 knots because of the added rotational resistance.


Bob
19' Dixie Craft

 

[gmc1962]

Re: 4 blade prop for 5.0l 19'

I use the Propulse also, the variable pitch is in 1" increments and it gives me the perfect RPMs. I compared the performance to my SS props and it was almost identical at the same pitch. So bang for the buck the Propulse is a good option.......and extra blades can be stored on the boat easily.