How to tell if a prop is actually stainless?

[496 Cubic Inches]

My dealer is going to install a stainless prop on my new 150hp Yamaha 4 stroke. He says they come painted black to deter theft. How can I tell if the prop is actually stainless? <br /><br />I'm paying for a stainless prop and I don't want to end up with an aluminum or steel.

 

[ob]

Re: How to tell if a prop is actually stainless?

No 100% mild steel late model props that I am aware of.The SS prop will be considerably heavier than aluminum.Far as I know , props are painted black to conceal an unpolished finish or forging flaws.The coating is also teflon content I believe and helps a bit on reducing surface rust.Probably helps a bit against oxidization on an aluminum prop.The aluminum prop won't pull a magnet.Many of the lower nickel/monel content stainless props will.I seriously doubt that your dealer would try to hose you ,but who knows.

 

[WillyBWright]

Re: How to tell if a prop is actually stainless?

Another big advantage of painting it regards corrosion. Bare metal props make great conductors in the water, which aids elecrolysis, which eats metal. Motors with bare metal props corrode much faster. Yamaha sells glossy white aluminum props and painted stainless props are dull black. Painting is cheaper than polishing, so they can be made and sold cheaper. Except in racing situations where fractions of a mph can mean the difference between 1st and 4th place, there is no practical reason to polish the prop nice and shiny. It's mostly for eye appeal ... it's mostly a Marketing thing. Give a blade a flick. Stainless props "ting". Aluminum props "twack".

 

[b.gagnon]

Re: How to tell if a prop is actually stainless?

I have seen some OMC SS props in the past come painted.

 

[PAkev]

Re: How to tell if a prop is actually stainless?

You will find the Yamaha part number stamped on the back hub along with the size and pitch.<br /><br />Compare this with the part number which Yamaha lists in this link<br /> http://www.yamaha-motor.com/outboard/products/perfbullpropdetails/3956/6G5-45978-03-98/propsku.aspx <br /><br />I have the same motor with black powder coated SS prop. I've dunked it in salt a few times and have worn the powder coating away. The prop that came with my motor was 13 3/4 x 19 but the prop the performance bullitan with my boat calls for a 17 pitch. I am only getting about 5300-5400 top RPMS with the 19 pitch and therefore plan on replacing it this season. I am going for the polished SS since I use it in salt a few times a year.