aluminum to stainless ?

[FishHog]

So I have a 1999 4.3L mercruiser in my 23' sylvan aluminum boat. It has a 13 3/4 x 21P aluminum prop on it now and runs well hits the right RPM so I'm good with its performance.

I want a spare prop, and was thinking about upgrading to a stainless and keeping this one as a spare.

If I do that, should I get the exact same prop in stainless to maintain the current performance?

Or should I just be happy with what I have and get a spare aluminum one?

thanks for the help guys.

FishHog

 

[r.j.dawg]

Re: aluminum to stainless ?

Stainless props are very unforgiving. In other words, if you were to hit something like a deadhead, chances are you could cause damage to your drive. Aluminum under the same circumstance would probably get bent up but will save the drive. Better to replace a prop than repair a drive.

 

[etracer68]

Re: aluminum to stainless ?

If your happy with the alum prop, I would stay with alum, if you are looking for a bit better performance, then try an SS 19 p. If the boat can go to the high end of rpm with the alum, maybe a 21p. I agree with r.i.dawg. I would see if you can use a SS prop from friend or dealer. Some people may suggest a 4 blade too. How big is your wallet. I have 4 props for my boat and will change them, depending on number of people in the boat and lake.

 

[FishHog]

Re: aluminum to stainless ?

thanks guys. I know ss is less forgiving, but there isn't much to hit where I boat. Had one on my last boat for 10 years with no issues. Just figured I might gain a bit of speed or fuel economy if I go to SS, but wasn't sure if I should get the same size of change. Boat can hit max rpm now with the Alum.

appreciate the info

 

[Texasmark]

Re: aluminum to stainless ?

You know what you have and how satisfied you are with it. With a new prop you are just fishing, hoping for the best, but setting yourself up for the worst.

I went through 3 SS props before I found one that gave me what I call maximum performance from my boat......was looking for every bit of speed I could get from my stock rig. Let's see $300 each roughly, on sale ......Hmmmm.

Most SS props are cupped, 2" pitch change, thin blades, 1" pitch change, high rake bow lifting, 2 inch pitch change, porting, 2" hole shot pitch change. These are the potential differences in your alum and a high perf SS in answer to your question "should I get the exact same prop in SS"......in short you can't. Yes you WILL get better performance from SS, but at what cost.

Food for thought.

Mark

Edit: Oh, and the prop that I liked the best for the best high speed performance, was so heavy and had so much pitch that my little triple Merc chugged and chugged at idle to the point where to load it on the trailer I'd shift between F and N to control the speed without all the chugging and banging. Didn't have that with the lesser pitch props.

 

[robert graham]

Re: aluminum to stainless ?

Maybe just get another aluminum prop just like the one you've got....for everyday cruising around, fishing, etc., I doubt you'd ever notice the difference in performance, especially considering the price of Stainless Props$$$

 

[Thalasso]

Re: aluminum to stainless ?

So I have a 1999 4.3L mercruiser in my 23' sylvan aluminum boat. It has a 13 3/4 x 21P aluminum prop on it now and runs well hits the right RPM so I'm good with its performance.

I want a spare prop, and was thinking about upgrading to a stainless and keeping this one as a spare.

If I do that, should I get the exact same prop in stainless to maintain the current performance?

Or should I just be happy with what I have and get a spare aluminum one?

thanks for the help guys.

FishHog

Check into a composite prop. I read they fall somwhere between aluminum and stainless in performance. You snap a blade on the composite you just replace the broken blade.

 

[cyclops2]

Re: aluminum to stainless ?

Well FishHog.

Your post was for a SS prop. Should be thinner blades which give you more speed or acceleration or a TINY bit of each if your present prop is close to perfect.

You need a VERY ACCURATE tachometer to do prop swaps. If it is wrong. You do not know if this prop is perfect or not. Any changes will be blind & time consuming. With a GPS in your hand or dash board you can do loads of swaps to see what helps.

The stock prop on my boat is excellent. The 5 L 220 hp Merc winds out to the rpm limiter just as I get the tilt trim right on maximum rpm at GPS 50 mph. If you can get the rpm governor & tilt trim to both peak with highest GPS speed. Join me & stay with your Aluminum prop.

That is all there is & there is no more to gain.

What EVER YOU DO. DO NOT buy any props!!!! Borrow them from a prop repair shop. Deposit required for any loss or damage to props.

 

[cyclops2]

Re: aluminum to stainless ?

I forgot to say how forgiving my 9 year old Aluminum prop is. Lots of idling clunks on rock shoals & ledges. Still doing 50 on the speedo & gps. The nicks on fat blades cause less losses then on a thin SS ding.

 

[FishHog]

Re: aluminum to stainless ?

good info, thanks guys