brass prop question

[krs60]

I googled and used the search here on the forums with no clear answer.

What is the deal with brass props? Are they vintage? How are they performance wise (better or worse than other props)?
I've only seen one before...it's on my 58 evinrude 50 starflite. Thanks.

 

[Frank Acampora]

Re: brass prop question

Brass is an alloy of copper and zinc. Bronze is an alloy of copper and tin. It is a very common error to call props brass when in fact they are bronze. The zinc in brass will dissociate from the copper --especially in salt water-- and corrode while the tin will not. THUS: All brass looking marine props and fittings are actually bronze.

Bronze and monel were the metals of choice for strength and durability before better casting and machining techniques were developed for stainless.

Bronze props were much stronger than aluminum and did give better performance. If you were racing, Bronze was the only prop to use.

However, now, except for some larger inboard boats bronze has been supplanted by stainless. In fact, for outboards you can not find a new bronze prop. Used and new old stock (NOS) is all that there is available.

 

[Texasmark]

Re: brass prop question

Brass is an alloy of copper and zinc. Bronze is an alloy of copper and tin. It is a very common error to call props brass when in fact they are bronze. The zinc in brass will dissociate from the copper --especially in salt water-- and corrode while the tin will not. THUS: All brass looking marine props and fittings are actually bronze.

Bronze and monel were the metals of choice for strength and durability before better casting and machining techniques were developed for stainless.

Bronze props were much stronger than aluminum and did give better performance. If you were racing, Bronze was the only prop to use.

However, now, except for some larger inboard boats bronze has been supplanted by stainless. In fact, for outboards you can not find a new bronze prop. Used and new old stock (NOS) is all that there is available.

Nice job Frank.

I was one of the first recipients of the OMC decision to go with SS. Cost me $185 for my 125 Johnny in about '73. It was referred to as the SST, was black Teflon coated and had a bronze diffusor ring that it didn't take much back country bass fishing to knock off. Bigggg improvement over my OEM alums. Prior to that, as I recall, Michigan wheel was the source for props, especially Bronze, if you wanted anything other than OEM alum.

Mark

 

[krs60]

Re: brass prop question

Great info, thanks a lot!