what size prop do i have?

[fisherman rick]

Hi everyone i hope someone can help me. I have read alot of post and it sounds like everyone knows there stuff when it comes to boats. I just bought a 1986 Astroglass fish and ski with a 1985 115 hp Mercury outboard. The person i got it from said they blew the hub out on the prop and just slapped another prop he had on the boat. Even though the tach is not working it does not sound like it is hitting high RPMs. I need to know what size prop i have so i have a starting point in getting the best prop for my boat. The only marks that i see is RM 315 cup. It is scatched up so the 3 might be a 5. The person i got the boat from said it had a ss prop on it and he took it in to get fixed but it has been i month now and he keeps forgetting to pick it up.....lol
Thank You

 

[steelespike]

Re: what size prop do i have?

There may be numbers under the prop nut. Being a merc they may begin with 48.
You'll need to havev thetach working and a speedo or gps so we can find the wot rpm and speed. lightly loaded.

 

[fisherman rick]

Re: what size prop do i have?

I have searched all over that prop and no more numbers. I am buying a tach this weekend and once i get the boat back in the water i can get speed and WOT info.

 

[steelespike]

Re: what size prop do i have?

You may have to have a prop shop measure it for you.