SS or Monel Shaft?

[billh22]

Looking for formation on the difference between stainless steel and monel shaft. When would you use one over the other?

[Fritz]

Monel is approx. 1/3 copper and 2/3 copper. K-500 is the sheet, but it is expensive. Monel makes a superior shaft material and is often used by the US Navy. The Leprechaun had Monel shafts when we stripped her last year and to the best of my knowledge these were at least 35 years old going to back to running gear damage I remember back in the 70's. I am no boat builder, but I think Monel is superior to stainless. Others may differ in their opinions.

[gottaflylee]

Monel is approx. 1/3 copper and 2/3 nickel. K-500 is the sheet, but it is expensive. Monel makes a superior shaft material and is often used by the US Navy. The Leprechaun had Monel shafts when we stripped her last year and to the best of my knowledge these were at least 35 years old going to back to running gear damage I remember back in the 70's. I am no boat builder, but I think Monel is superior to stainless. Others may differ in their opinions.

Monel has a specific gravity of 8.82

Stainless is about 10.5 I think...

[Fritz]

Monel has a specific gravity of 8.82

Stainless is about 10.5 I think...

There are of course varying grades of stainless.

[terr]

Here are a couple of links that may be of use.

A comparative chart of different marine metals, shaft and otherwise.

and Aquamet grade comparison.

Marine Machining and Manufacturing is a company that machines Aquamet shafting. I don't think they make Monel shafts. I have not found any numbers from a maker of Monel shafting.

It looks to me the size shaft you need can factor in on which material is best. Based on the Charpy test it looks like the Aquamet 19 has the best impact resistance, i.e. less likely to crack if you ground of hit something big and log like. That is what a lot of the charter boats out of Oregon Inlet and Hatteras use.

That being said it is hard to argue against 35 years of use.