SS vs Aluminum

[roadrunnr]

I damaged an aluminum prop this weekend on my 1989 SR 1700 17 foot Maxum with a 85 HP Force running a 13 1/2 X 15 prop. The engine RPM at WOT is around 5200, speed is about 35 MPH. I believe the engine is propped correctly, my question is, will a SS prop of the same size and pitch give me any performance increase. I have a line on one that is used but in pristine shape, or am I better off sticking with aluminum. I'm running with my spare aluminum prop, so repairing the damaged prop will not keep me off of the water! Thanks for your replies!

 

[Frank Acampora]

Re: SS vs Aluminum

The stainless will usually give about 200-400 RPM more and usually about 2 MPH more with the same brand, style, and pitch. I only use stainless on my Force engines. All my aluminum props are spares!

Now, here is the disclaimer: Different brands of props run differently so it is possible that the stainless will load down the engine more. Additionally, if the stainless is cupped, it will only increase RPM by about 200 over the aluminum.

However, I say: Try it. Stainless in good condition is relatively easy to resell if you don't like it.

 

[roadrunnr]

Re: SS vs Aluminum

Thanks Frank, I'll see if it's still available and give a try if it is! I'll post my opinion after this coming weekend!

 

[craze1cars]

Re: SS vs Aluminum

I have found the opposite to be true regarding RPMs.

Usually stainless will turn slower than aluminum of same pitch, because stainless is more efficient and bites the water harder...so I say you might see a 200 RPM loss while maintaining or slightly improving on speed/holeshot. If you see a 200 RPM gain, it means the stainless was less efficient than the aluminum it replaces, and it is slipping...

This will vary all over the board by design of your current prop, design of replacement prop, etc...

Noticability of improvements goes up with HP. Small HP motors like your 85 outboard will see substantailly less benefit from stainless, when compared to putting one on a 250+ HP application...

I agree that nothing can answer the question better with absolute facts than an actual test-drive...

 

[FichtFan]

Re: SS vs Aluminum

Typically if it's the same prop dimensions, stainless will give better results. However, I don't run one because if I ever hit something I know the prop will break before the lower unit is damaged (typically). If you hit something with a stainless it is much more likely that you will damage the lower unit because of the rigidity of the stainless prop. So be careful since the reason you are getting a new prop is because you already hit something.

 

[Icyharp]

Re: SS vs Aluminum

I have both easily within reach. On lake I know well I run my stainless, on some of the rockier lakes I will switch to the alum. Reason for it that is the alum one is way more forgiving than the stainless one. I have seen too many shafts sheared off or twisted from a stainless prop, I would rather limp in on a damgaged alum prop than be towed in and have to have the lower unit fixed. Just my 2 cents though.

 

[Icyharp]

Re: SS vs Aluminum

Typically if it's the same prop dimensions, stainless will give better results. However, I don't run one because if I ever hit something I know the prop will break before the lower unit is damaged (typically). If you hit something with a stainless it is much more likely that you will damage the lower unit because of the rigidity of the stainless prop. So be careful since the reason you are getting a new prop is because you already hit something.

LOL we must have been typing at the sametime......

 

[roadrunnr]

Re: SS vs Aluminum

Typically if it's the same prop dimensions, stainless will give better results. However, I don't run one because if I ever hit something I know the prop will break before the lower unit is damaged (typically). If you hit something with a stainless it is much more likely that you will damage the lower unit because of the rigidity of the stainless prop. So be careful since the reason you are getting a new prop is because you already hit something.

I actually didn't hit anything, but foolishly had the lift too low and loaded the boat too far forward. What should've stopped the lower unit instead bent one of the prop blades. While anything can happen I boat in Green Lake, which is the deepest lake in Wisconsin so I'm not overly concerned about hitting anything, as I haven't in the past 8 years. Transport to a different lake and the switch back to aluminum would be wise. I am concerned about an 85 spinning a heavier prop. I'll see what happens this next weekend and report back. I can return the prop for credit if I'm not satisfied, but not a full refund!

 

[Bamaman1]

Re: SS vs Aluminum

Aluminum props are getting better--erasing some of the performance gains with stainless steel props.

I used to have to rebuild or purchase a prop a year when using aluminum. When I switched over to stainless, I've gone 12 years on the same propeller. To me, stainless steel is a long term investment--that pays off in durability alone.

 

[Irv964]

Re: SS vs Aluminum

Aluminum props are getting better--erasing some of the performance gains with stainless steel props.I used to have to rebuild or purchase a prop a year when using aluminum. When I switched over to stainless, I've gone 12 years on the same propeller. To me, stainless steel is a long term investment--that pays off in durability alone.

Couldn't agree more with the bold, been running a Turning Point prop now for a few years and have no desire or reason to even try a SS prop.
I bought for cost, more forgiving, and vertially zero theft risk. (review below)
http://forums.iboats.com/showthread.php?t=269778&highlight=review+turning+point+props

 

[roadrunnr]

Re: SS vs Aluminum

Well, tried the SS prop this weekend and the results were disappointing! The WOT RPMS dropped by 200 and the speed dropped by at least 2 MPH. I believe the hole shot an turning was better. Looks like this is way too much prop for an 85 HP and I'll probably go back to the aluminum.

 

[FichtFan]

Re: SS vs Aluminum

Atleast the weather this weekend was nothing short of AWESOME! lol

 

[mrdancer]

Re: SS vs Aluminum

FWIW, in my 25 years of boating in shallow waters, I've run about a 50/50 mix of aluminum and SS props. I've broken/bent three prop shafts in that time, and all have been with aluminum props. Now, I only run SS. However, my hazards are stumps and shallow sandbars, not rocks, so YMMV.