Buying new SS prop

[countvlad]

Because my current 17 pitch Stiletto Advantage SS prop is banged up and because I'm only turning 5200 rpms, with my setup, I decided to repitch it to 16 and also purchase a jack plate. I called the local prop shop today and he quoted me @200 to get the prop repitched plus he said that he doesn't recommend re pitching the SS prop.

Looking around the internet i found a web site that sells the 15' stiletto prop for $240. So my question is: if i get the 15' prop that should bring my rpms up from 5200 to approximately 5600,correct? if so how much would the jack plate raise the rpms up by, 200?

According to my assumptions that should put me around 5800 or would that number be lower/higher?

Should I get the 15' prop? or a different pitch based of the rpms that I'm currently getting out the boat?

 

[Frank Acampora]

Re: Buying new SS prop

The generality is that a two inch change in pitch of the same prop will result in about a 400 RPM difference.

However, while dropping to a 15 pitch, depending upon hull and other factors, while RPM may rise, speed may either stay the same or drop.

A jackplate does not raise RPM per se. It sets the engine back a bit into cleaner water and you can raise and adjust the engine height on the transom for maximum performance.

Best if BEFORE you drop big bucks, if at all possible, test a couple of props.

OH, and by the way: It is a GIVEN that the other fellows on this forum will be asking for much more info--engine size, hull type, length, weight, average load, etc. Without these numbers, a proper recommendation can not be given.

 

[Dhadley]

Re: Buying new SS prop

We always like to see folks make one change at a time. Adding a jackplate may indeed help your set up to the point you can reach your target rpm with the 17" pitch. It might be helpful to know what boat & motor we're dealing with.

 

[countvlad]

Re: Buying new SS prop

The motor is a 120 Hp 1989 Johnson
1976 Rinken 19" CC Deep V
weight: 1600lbs average: 2000lbs
with the old aluminum prop: 41@5800 (GPS)
cruising speer aluminum: 31@4400(GPS)
SS Stiletto: 43@5200(GPS)
cruising speed Stiletto: 33@4200(GPS)
current prop: diam 13 1/4' , 17 pitch
i dont do any water sports so usually i either troll(for striper or crab) or cruising to a fishing or crabbing spot.

ok so what do you guys recommend: fix the 17' SS and go from there? would i be able to achive my 5800 goal with a jack plate? what should be my next move?

 

[PROPer]

Re: Buying new SS prop

Dhadley had an excellent point... If you are set on getting a jack plate, do that first and then run your current prop on it. That could change the way the boat and motor runs and it might be better regarding the RPM. Once you get that jack plate up a bit, you will most likely get some more RPM.