SS prop

[Jamesnl]

I have a 1725 explorer ss with alum prop 19 pitch, would like to up-grade to SS, what pitch and prop would you recommend? Thanks 115 4-stroke mercury

 

[180shabah]

Re: SS prop

Gonna need some more information if you want any meaningful recommendations...

If you read through the stickies, you will see what is needed...

 

[limitout]

Re: SS prop

the important thing is do you need a different aluminum prop? because just swapping to a ss prop doesn't change the pitch you need so if your not trying to solve a problem get the exact same prop you have now but in ss

not trying to insult because oi don't know what you do or don't know about props but you only need to change pitch or prop design if there is a performance issue you are trying to resolve

 

[Jamesnl]

Re: SS prop

Slow out of hole, top end 38 mph, at 5600 rpm, wondering if I would get better performance?

 

[Texasmark]

Re: SS prop

Slow out of hole, top end 38 mph, at 5600 rpm, wondering if I would get better performance?

You could up the load on the engine a tad beins you are over the upper limit of your rpms. Increased pitch will do that if you stay with the same prop from the same mfgr. Rule of thumb is 150-200 rpm per inch. So increasing your pitch with the same prop from the same mfgr 1" will get you about 2 or 3 mph improvement....SWAG (Scientific Wild Arsed Guess) and drop your rpms to within the upper limit of the RECOMMENDED rpm range. Course for that small change, why bother? Human nature. We are never satisfied, regardless. Always want something better. Ok fine.

Mark

 

[SkiDad]

Re: SS prop

if you have poor hole shot i would move to a 17 pitch prop - that will get your RPM closer to 6000 and improve your hole shot - right now you have 12% slip, which is average, so I would say you speed would drop to approx 37 if you stay with the same type of prop but lower pitch but you will have a much nicer running setup. My guess is your boat is pretty heavy loaded ?

 

[jayhanig]

Re: SS prop

Not to hijack the thread but you mention slippage. How do you calculate that?

 

[SkiDad]

Re: SS prop

I used Propeller Calculator / Prop Calculator

I used 2.33 for gear ratio. You have to look up the ratio for a particular engine. Then plug in 3 of the other numbers and the 5th one will be calculated for you.

 

[Texasmark]

Re: SS prop

Not to hijack the thread but you mention slippage. How do you calculate that?

go-fast.com has a BAM prop slip calculator that I use. You can plug in different types of numbers and it will calculate the missing info for you.

Mark

 

[steelespike]

Re: SS prop

According to the Merc site the 115 is rated for 5800-6400 rpm
At 5600 your not even in the range.
As suggested a 17" prop could add up to about 400 rpm.
The Solas Amita and Rubex have a good reputation for good predictable performance.
It will very likely feel like a new motor and at about 1/3 the cost of stainless.