I was wondering if anyone knew of any shops that carry props that I could try out on my 2004 yamaha 25hp 2 stroke. I think I have too much pitch but I don’t know my rpm’s so its kind of a shot in the dark. I’m thinking I have too much pitch. Any suggestions?
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.”
-Benjamin Franklin
Malibu Stealth 12
94 J16 Carolina Skiff/2004 yamaha 25
not to many props available for a 25! Good luck!
Do you have a tachometer or have any idea what RPMs it’s turning with the current prop? Need to know RPMs to match prop size. It should turn up to very close but not over 6,000. A Tiny Tach connected to a spark plug is probably the easiest way to measure a 25 hp.
Capt. Larry Teuton
Cracker Built Custom Boats
“Ships are the nearest things to dreams that hands have ever made.” -Robert N. Rose
quote:
Originally posted by Cracker LarryDo you have a tachometer or have any idea what RPMs it’s turning with the current prop? Need to know RPMs to match prop size. It should turn up to very close but not over 6,000. A Tiny Tach connected to a spark plug is probably the easiest way to measure a 25 hp.
Capt. Larry Teuton
Cracker Built Custom Boats“Ships are the nearest things to dreams that hands have ever made.” -Robert N. Rose
I have nothing to check, but I might look into a small tachometer if that it’ll help.
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.”
-Benjamin Franklin
Malibu Stealth 12
94 J16 Carolina Skiff/2004 yamaha 25
quote:
Originally posted by Cracker LarryDo you have a tachometer or have any idea what RPMs it’s turning with the current prop? Need to know RPMs to match prop size. It should turn up to very close but not over 6,000. A Tiny Tach connected to a spark plug is probably the easiest way to measure a 25 hp.
Capt. Larry Teuton
Cracker Built Custom Boats“Ships are the nearest things to dreams that hands have ever made.” -Robert N. Rose
Now does one do this while the prop is on or off of the motor? In or out of the water? Loaded with people and gear or no?
Fishing Nerd
“you win some, you lose some…but nothing beats getting some!”
Can’t help you on the rpm but, I had a 25 yami on a CS J16. I had 3 props. A 12 for redneck riding real fast, a 10.5 for all around use, and a 9 for shrimping and duck hunting with a loaded boat. 9p ran 20mph, the 10.5 was about 26 and the 12 was in the mid thirties. The 12 was only good for like 1 adult and a kid - 2 adults and it took a ways to plane out. On the other end the 9p would jump on plane quick - just would not go very fast. It would plane out and ride good which is better than plowing along like a tug. I never had a tach and boat came with old beat up 12p and the 10.5. I took a chance on the buying the 9p 'cause we got tired of plowing along shrimping. It was wound up but, rpm didn’t sound any higher than any other engine I ever ran at wot.
J Ford
You can’t catch 'um on the couch!
That’s kind of funny to keep 3 props but I guess I see where you’re coming from! I figured someone had some advice on input of how exactly to measure RPM’s…chris v? Cracker Larry?
Fishing Nerd
“you win some, you lose some…but nothing beats getting some!”
quote:
Now does one do this while the prop is on or off of the motor? In or out of the water? Loaded with people and gear or no?
Prop on motor, yes, in the water yes, normal load in boat. You can probably borrow or rent a strobe light tachometer, or buy a Tiny Tack for not a lot that hooks to a spark plug. See tinytach.com.
A lower pitch prop turns more RPMs, a larger one less. The motor has a rated RPM range it should run it, without over revving, or bogging down the engine. Different hulls and weight loads need different props. I went through 5 on my my boat to get it perfect and that was with a good tach. Without knowing the rpms under load you are just shooting in the dark. It’s half science and half black magic.
Capt. Larry Teuton
Cracker Built Custom Boats
“Ships are the nearest things to dreams that hands have ever made.” -Robert N. Rose
I’m with larry. You have to have a tach to get it right. I run the same motor as the OP on a 1553 with a 13p prop. I see about 31mph at WOT.
That’s the info I was looking for! Thanks again!
Fishing Nerd
“you win some, you lose some…but nothing beats getting some!”