stainless on a 40hp?

[1973Chieftain]

I am putting a '96 Force onto my 15' aluminum boat, which I plan to use for general boating and pulling a tube. My engine needs a new prop and I am debating on either a ss or aluminum. I have heard that the benefits of ss would not be noticable on a small engine like a 40- is this true? Would there be a noticeable difference? Thanks for your ideas!

 

[steelespike]

Re: stainless on a 40hp?

If you read "read this first" at the top of the page and the helps on the prop store page it will help you understand
prop selection
The good news is your prop is the same as the same year Merc 40 so more are available than older Forces.
You should be able to get your prop repaired, then do some test runs and get us the wot rpm and speed,by gps.
A ss prop will cost about 3 times that of an aluminum. If your boat was setup well with a good al prop the ss
could provide performabce improvement across the board that could range from a few tenths to a few mph.
If you boat where a hard contact is likely the ss will cost about twice as much to repair. If a soft contact is likely(sand or mud)
the ss may hold up better. Depernding on where you boat a al repair is probably 40-60 ss about twice as much.

 

[1973Chieftain]

Re: stainless on a 40hp?

Thanks for the reply steel! I read the sticky first, but since I don't have the engine on the boat yet, nor do I have a specific problem. My question is more along the lines that I have never used a SS prop. I've heard they can increase performance on larger engines but that the benefits are negligible on a 40. I am wondering if this is correct?

 

[steelespike]

Re: stainless on a 40hp?

I think I covered it pretty well.Assuming an al prop setup the is really good the ss results would be less impressive.
I do think that on a boat able to make 50+ mph easily that a ss prop has more of a chance to larger improvements.
If your dealing with a fast boat that may not be at its peak I think there is room for more improvement.
Than in a boat with a max speed of say 35. A 50 mph boat 10% short of speed might gain 5 mph or more
A 35 mph 10% short you have only about 3.5 mph to make up.There are a number of al props that can perform close to ss.
The Turning point Hustler and Rascal are 2.There is no doubt that a ss prop will very likely improve overall performance.
But you can't make a blanket statement of impressive improvement there are too many variables.
It is generally thought that a boat that runs over 50 is less likely to gain signifigant speed with a prop change.
There are 135 hp boats that run about 35-39 mph that would require about 200 to 220 to run around 50.
I think that you could see a change to stainless isn't likely to add a lot. if your near the top of those speeds in the first place.
Then there are props that might produce excellent top speed but may fall short on hole shot and viceversa.
There are those that will spend 100s and some 1000s of dollars for a couple of mph.
If a person has a boat with a poor setup they might add 5 to 10 mph and maybe not even buy a prop.
Jeez I'm rambling.lol