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Author Topic:   Propellers 101-Aluminum/Stainless steel
Jim Turnbull posted 04-15-2002 12:41 PM ET (US)   Profile for Jim Turnbull   Send Email to Jim Turnbull  
Need some help on this. In simple terms, why is a stainless steel prop more effecient through the water than an aluminum one?
Why is it that an engine outfitted with a stainless steel prop will be 3 to 5 mph faster than an identical engine with an aluminum propeller?
If I want an extra 5 mph, is the SS prop the way to go??
where2 posted 04-15-2002 01:15 PM ET (US)     Profile for where2  Send Email to where2     
SS is stiffer than Aluminum. Therefore, SS can be made thinner, and will have less blade flex than a similar aluminum. With less flex of the blade, and less resistance to the water, more of your HP pushes the boat forward with every revolution of the engine.

There's the simple explaination.

jimh posted 04-15-2002 02:10 PM ET (US)     Profile for jimh  Send Email to jimh     
See for some discussion of this.
Bigshot posted 04-15-2002 02:19 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
You theoretically gain 3-5. I get more to end with an alum right now. Once you break 40+mph it is more crucial to performance. I only run SS props but am having a tough time finding one that performs better than my aluminum.
Jim Turnbull posted 04-15-2002 06:16 PM ET (US)     Profile for Jim Turnbull  Send Email to Jim Turnbull     
Thanks for the comments guys.

I have a 1999 13 GLS. Currently I am using a 15inch pitch aluminum prop on my Mercury 40 2 cylinder 2 stroke engine. Using my GPS receiver, I have measured my speed at between 35 - 36 mph.
If I switch to a 15 inch pitch stainless steel prop, am I likely to increase my top end speed by much? Say up to 40 mph?


EasyE posted 04-15-2002 06:36 PM ET (US)     Profile for EasyE  Send Email to EasyE     
Yes you would get more like 40mph. If you dount carry alot of load, I would say a 16pitch to be on the safe side.-EasyE
EasyE posted 04-15-2002 06:44 PM ET (US)     Profile for EasyE  Send Email to EasyE     
I wonder if Whaler still has the mold for the older 13's. Perhaps I can special order one for say $10,000? It should be worth big bucks in about 40 years?
kamml posted 04-17-2002 06:58 PM ET (US)     Profile for kamml  Send Email to kamml     
BS is it possible you have reached maximum hull speed with the weight/hull design and HP available? Is is possible to reach a theoretical maximum speed with a given setup and the only way to gain any additional speed is with additional HP regardless of prop configuration?
lhg posted 04-17-2002 08:50 PM ET (US)     Profile for lhg    
Jim T - If you really want to make that Mercury run, get one of the newly designed Mercury SS Trophy Sport 4-bladed performance props for it. I hear they are super, and are for engines in the 30-60Hp range.

Conventional SS props ("elephant ear design") give better acceleration, better holding, a little more bow lift, and better top speed than aluminums. Mercury says the thinner, and stronger blades have less drag. Jumping to their performance lines, like this Trophy Sport model, for boats that will do over 35, enhances these qualities even farther.

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