Which would you pick going form AL to SS???

[packerman]

Hi
Changing from AL to SS prop. I have a 14 1/4 x 21 aluminum prop now that works well. WOT has changed from 4800 RPM to 4900, with a little use and a few tiny nicks. So being 100 RPM over WOT and wanting a SS prop anyway, I'm looking at Ebasic Marine's, SS Express prop and Overton's, SS Stiletto prop. Anyone have thoughts as to which prop they would choose and why. Thanks..................

 

[Texasmark]

Re: Which would you pick going form AL to SS???

If you really want the correct answer, try before you buy, period. There are so many variables that affect performance. Things you expect just don't necessarily happen. BTDT

The old salts on here say to perfect your setup then go after the prop. Makes sense to me. Course if you have an I/O (you didn't say) nothing you can do to the setup.

HTH

Mark

 

[mwmotorsports]

Re: Which would you pick going form AL to SS???

I was using a 12 3/4 x 21 aluminum for the longest time with great results on my boat. A couple weeks ago I chipped the prop and got a used stainless at a great price for a quick fix at the same size and pitch as the aluminum. Well, after I bolted it on and went to the river the boat wouldn't go anywhere. I could not believe the difference in performance. My motor just couldn't push the same size prop in stainlaess as it did in aluminum. It seemed like I dropped about 500rpm's at least and top speed was 28mph compared to 42 with the alum. Watch what you buy compared to your aluminum. I am thinking dropping 2 sizes in stainless to get the same performance as alum. Luckily I got to return my prop and got my alum one repaired.

Good luck.

 

[packerman]

Re: Which would you pick going form AL to SS???

It's an I/O. I thought the SS would bring it back down into WOT range and I'd still have 400 RPM of room to work with (4400-4800). Seems pretty safe w/that much room to work with. Thanks for your thoughts guys!!! P.S. Texasmark... what's BTDT and HTH mean. By the way, my sister has been married to a SA Texasmark for about 20 years now. She's a couple thousand miles away...........................

 

[Texasmark]

Re: Which would you pick going form AL to SS???

Been There Done That!

Hope This Helps!
--------------------------
On the comments, appears to me that the SS was way higher performance than the alum causing a load on the engine and I'd guess preventing the engine from being able to reach the peak of it's torque curve. Being an I/O it is possible that the boat was unable to come out of the water enough to realize gain from the higher performance.

Sometimes boats perform better with the same dimension of SS (over alum) because the SS is usually higher performance and the hull is able to rise up out of the water more, reducing drag, thus requiring less hp to do the same thing, so for a given setup you wind up going faster and sometimes turning more rpm's. This happened to me on a light fast hull. I had a 17P SS and it was way under propped. I went to a 21 figuring (calculated) that this was just right. Wrong again. Went to a 3rd prop of 24" and was still 100 rpms over max but the boat speed was stellar....48-50 gps out of a little 90 hp on a 17' boat....wake pic in my avatar.

SS is usually cupped and alum usually not so folks on here use 1" additional pitch for cupping which translates to approx 250 rpm drop with the same dia/pitch in SS.

So, like I said, the only way you really know is to try it before you buy it.

HTH,

Mark

 

[Tail_Gunner]

Re: Which would you pick going form AL to SS???

It's an I/O. I thought the SS would bring it back down into WOT range and I'd still have 400 RPM of room to work with (4400-4800). Seems pretty safe w/that much room to work with. Thanks for your thoughts guys!!! P.S. Texasmark... what's BTDT and HTH mean. By the way, my sister has been married to a SA Texasmark for about 20 years now. She's a couple thousand miles away...........................

A few thing's, type and year, boat lenght, motor size and what are you looking for, all out speed or hole shot for water sport's?