Yamaha 21- M Saltwater Series Prop markings

[maineidyl]

I got a spare prop for my Paramount when I purchased it. In looking over it, I found markings on the rear hub that says 14 7/8 x 21 M. It is also marked on the outer hub 21-M. What I do not know is if the markings on the prop hub RSS 67645 is a factory marking or does this mean the hub was re-pitched etc....Any idea what this means. I plan to try the prop this weekend but would like to know if it is a 21 pitch or larger.

Can a shop reduce the pitch or can props only have the pitch increased?
Thanks in Advance
Tom
2003 Paramount
2003 Yamaha VMAX200

[XstreamVking]

21M means 21 pitch. The other numbers sound like a prop shop has marked it for their id purposes. Props can be re-pitched up or dn 1-2 inches in pitch. It is not generally best to re-pitch a prop. Better to get a correct pitch one. jmho

[maineidyl]

Thanks. I did not understand the RSS markings. Guess I will just try it and see how it works on my VMAX.
Tom