Which numbers on the prop are important

[weekendfisher]

Hey Guys
I have a Johnson 50Hp with the small gear case my prop is pretty banged up so i want to replace it.
The markings on it are 11-3/4-17 what I want to know is the 11-3/4 a sige number to indicate the diameter or is that two separate numbers with different numbers ?
The reason i as is that it has been very difficult to find that size in Aus and Iboats aren't shipping outside of USA or Canada at the moment and i am in a bit of a rush to replace the prop.
As it is damaged i am not willing to run it to WOT toget all of the figures so i need to replace it with something the same or very similar.
So far i have the option of 12 1/4*15 which i believe is a smaller pitch which would lower my top end speed
13 1/4*17 so larger diameter but same pitch as original ???
That is what is locally available without having to order one in... Will either of those suit or should i try chasing some outboard wreckers as i need it for the weekend.
Thanks

 

[tpenfield]

Re: Which numbers on the prop are important

verify the diameter with a tape measure, but . . .

it looks like you have 11-3/4 " diameter and 17 inch pitch.

 

[Georgesalmon]

Re: Which numbers on the prop are important

Diameter is not as important as pitch. If you can't get your WOT RPM numbers I think you should stay with 17 pitch, going down to 15 may allow your moter to over rev. which is not good. Although going up in diameter and down in pitch may work OK and depends on where you were in the WOT RPM range for your motor to start with. Hard to tell for sure without trying it and getting those numbers. And, your speed might even stay the same since the 15p may allow higher RPM.