SS vs. Aluminum

[jstaz]

I am new to the boating thing and am learning fast. I have been looking at props and pitch and all that and have noticed that SS is far more $$$ than aluminum. I have heard SS has better performance and durability because the material is harder than aluminum. Just how true is all that? I want to get a new prop because the one I have is aluminum and is a little beat up. So, is it worth spending the extra money on the SS prop or does it not make much of a differance?

I have a 17 foot fiberglass boat with a 60 hp Tohatsu. GPS says it goes about 30 mph. I typically fish on the river and Mobile Bay.

Any help would be great. Thanks in advance.

 

[steelespike]

Re: SS vs. Aluminum

Stainless props are more durable when soft contacts(sand,mud)are likely however if hard contacts are likely while they hold up better repairs are more.A L. props are easily damaged and easily repaired.Generally ss props will out perform aluminum
but there are AL. props the do very well at about 1/2 to 1/3 the money.
Is the motor 2 stroke or 4 stroke?Year? Your wot rpm and speed?

 

[paultjohnson]

Re: SS vs. Aluminum

An aluminunumumum prop provides protection to your drive in that if you hit sumtn The prop blades break .. SS will transfer much more shock to your lower unit.
SS is more rigid, so you get somewhat better performance. Probably wouldnt notice much diff in your lower Horse Power engine. An alumimimumumum prop has a little bit of flex when u put alot of HP to it.
I put an alum prop on years ago - knocked 1/4th of each blade off 1st use. took me 5 mins Been running SS ever since and I make sure my insurance covers underwater inpact

 

[Bifflefan]

Re: SS vs. Aluminum

I typically fish on the river and Mobile Bay.

Unless that river stays deep, and has no hidden trees, rocks and such, i'd stay with alum or composite. They can take a hit and leave you with a good working drive still.

 

[FHB]

Re: SS vs. Aluminum

I bought my boat used. It had a stainless prop on it 20:1. A buddy told me that was the wrong prop and that I should run a 15:1. Money was tight so I bought an aluminum prop. The performance difference was huge even in aluminum. Having the right prop made a big difference - I would guess more than the metal.

Frank

 

[jstaz]

Re: SS vs. Aluminum

Thanks for all the input. I am thankful to have gotten such a good response. I am thinking about going alum.

Oh and my motor info is as follows...

1994 Tohatsu M60B 60 HP rpm range 4800-5100 RPM I think 2 stroke.

Another question for you all,
I took the current prop off it find the size and pitch and I can not find that info on the prop anywhere. Any help would be great. Where can I find that info? It is not stated in the owners manual. All it says is the typical factory pitch that model comes with is 13.

 

[Robbabob]

Re: SS vs. Aluminum

Thanks for all the input. I am thankful to have gotten such a good response. I am thinking about going alum.

Oh and my motor info is as follows...

1994 Tohatsu M60B 60 HP rpm range 4800-5100 RPM I think 2 stroke.

Another question for you all,
I took the current prop off it find the size and pitch and I can not find that info on the prop anywhere. Any help would be great. Where can I find that info? It is not stated in the owners manual. All it says is the typical factory pitch that model comes with is 13.

A 60HP set-up that does 30 mph, , , sounds pretty good the way it is. What is your actual rpm at WOT?

The diameter and pitch should be on the back of the prop near the inner edge. Something like 12X13. I assume the 13 at the end since your documentation states 13" pitch is typical for the engine.

I also wouldn't bother with SS. Aluminum flexes, but under higher load than what your boat should see.

 

[jstaz]

Re: SS vs. Aluminum

The last time I took my boat out the WOT rpm was 5100 right at my manuals stated top range.

I will take my prop off again and look for the size. I could have missed it. Is there any chance that the size would be stamped underneath the hub? Would I have to remove that to see it?

 

[Robbabob]

Re: SS vs. Aluminum

Given that you are at your top rpm at WOT. Increasing pitch 1/2" should drop your WOT rpm while increasing speed. You will lose a little hole shot in the process.

You should be able to see the size while the prop is attached. The problem is that it may be worn or pitted (as you state the prop condition). Look closely around the nut on the prop -- use a flashlight and feel with your fingers for any digits.

Hope this helps!

 

[jstaz]

Re: SS vs. Aluminum

Iwill definately try feeling for the size. I know there is pitting around that whole area. So, my guess it will be difficult to find it but I will look. Thank you for your help. I will try a higher pitch.

Is there a brand of prop that is better to have than others?

 

[rolmops]

Re: SS vs. Aluminum

this little pdf file might be of some help.It may look like mostly advertisement,but it holds a treasure of information.
http://www.propline.com/Propeller-General-Information/Michigan_Wheel.pdf

 

[Expidia]

Re: SS vs. Aluminum

I'd Google prop repair shops. I've sent mine in 2-3 times already. They repair them (even a broken off ear) and spray them like new for around $30 plus $5 shipping.

You may get them repaired locally too, but probably for more money.

Even if you buy a new one get your old one repaired and keep it on board as a spare.

SS is expensive, more appropriate for larger outboards and is "very" easily stolen right off your outboard unless you spend even more for a prop lock nut or similar device.

Like others have said . . . SS can blow your lower unit where aluminum absorbs the impact. . . . ask me how I know this like 3 times already

 

[jay_merrill]

Re: SS vs. Aluminum

I went from an aluminum prop to a SS prop of the the same diameter and pitch. I did it because I wanted greater ability to hold plane at the lower end of my speed range.

I have a trihull and one of the techniques that works well for reducing "pounding" when operating into a headwind (sea), is to just slow down. I can reduce to about 12 mph, which kicks the bow up quite a bit. My SS prop will hold this configuration better than the aluminum prop did, because it has less flex in the blades.

As a bonus, I ended up gaining about 125 rpm at WOT. Since I was in the midrange of my acceptable WOT, this bumped me up a little closer to the top of the range and reduced "lugging." I suppose I am running a little higher at the 12 mph speed too, which probably adds to my ability to remain stable in that speed range.

The top end that I get with the SS prop is only slightly higher than with the aluminum prop. Flat out, I make around 29 mph (gps), which isn't particulalry fast compared to many of today's boats, but is just fine for me, especially since I have half the rated hp on my boat.



???

 

[WIMUSKY]

Re: SS vs. Aluminum

I went from an aluminum prop to a SS prop of the the same diameter and pitch. ???

I read somewhere that if you go from aluminum to SS that you need to change the pitch on the SS. I forget if you go up or down. Just a guess, but, maybe down to accomodate the extra weight of a SS? Is it true to change the pitch? Anyone?

 

[rolmops]

Re: SS vs. Aluminum

It is true ,but not always.
The difference between stainless and Aluminum of the same pitch is often an increase of 200 to sometimes 300 rpm at WOT. If you go higher than max rpm at wot because of a change to stainless,you should increase your pitch accordingly,that way you will not over rev your engine at wot.
but if your engine was lugging before,the stainless can bring the RPMs up to where they should be at WOT.In this case you should not increase your pitch

 

[Robbabob]

Re: SS vs. Aluminum

Let's look at the repair side a little closer.

You are currently operating within specification with a prop that needs minor repair. Chances are, fixing your current prop will improve eficiency and most likely reduce max rpm (unkown until repaired).

Think strongly about having your current prop repaired... they will also be able to tell you what size it is. You may find it works perfect and a change would have been detrimental.

On the flip side, if you still make a change, you have a newly refinished prop that you know the size of for advertisments Instead of going to the junk pile, you'll be able to recoupe your repair money and everyone is happy.

Let us know which direction you go........

 

[jstaz]

Re: SS vs. Aluminum

I was really thinking about getting a second prop just to have a back up. I hear from a lot of people that it is wise to have a back up on the boat in case something happens. I don't think my current prop is in that bad of shape. I am not sure if it even really needs to be fixed. I will post a picture soon to see if y'all think it should be fixed. there are a few nicks but not as bad as other props I have seen. Are there some guidelines to follow to judge if your prop needs to be replaced/fixed?

 

[Tail_Gunner]

Re: SS vs. Aluminum

Manufacturer: Tohatsu
Model: "M70B"
Year: 1994
Horsepower: 70.0
Cylinders: 3
Type: 2 stroke
Gear Ratio: 1.92:1
Min WOT RPM: 4900
Max WOT RPM: 5600
Spline Count: 13
Drive Type: Outboard


http://www.go-fast.com/Prop_Slip_Calculator.htm

Your gps speed is 30mph...gear ratio 1.92...Just need the actual pitch. You may go the outboard section and find where that motor runs best...theres quite a spread in the rpm band there..