2002 johnson 25hp wrong prop

[blank454]

I bought a boat from a guy that told me he had changed the prop to a 20hp prop, meant nothing to me since I can't tell the diff just by looking at them, so I check my owners manual and found out it should have a 10 by 13, I look at my prop and its stamped 10 1/2 by 11. If I put the recommended prop on it what difference should I expect? Thnx.

 

[steelespike]

Re: 2002 johnson 25hp wrong prop

It all depends on what boat you are running.Speaking very generically a 13 will have slower hole shot but if able to turn up the prop more speed.
Again the 11" may do fine depending on the load. You should have a tach and gps or speedo
to evaluate your set up.If you read the stickys at the top of the page and get us as much info as possible we can fine tune your setup.

 

[blank454]

Re: 2002 johnson 25hp wrong prop

It all depends on what boat you are running.Speaking very generically a 13 will have slower hole shot but if able to turn up the prop more speed.
Again the 11" may do fine depending on the load. You should have a tach and gps or speedo
to evaluate your set up.If you read the stickys at the top of the page and get us as much info as possible we can fine tune your setup.

K, its pushing a 15ft Lowe aluminum flatbottom, the 13 should run 4500-5500rpm @ full throttle so the manual says, don't know what my 11" is turning, don't have a tach/speedo etc. Did notice while running down the river top end seems to be lacking, all I could do to run down an old 9.9 johnson (which was on a considerably smaller boat, and had been modified)

 

[steelespike]

Re: 2002 johnson 25hp wrong prop

For the health of your motor you need to know your rpm and speed. Based on your description
it would appear more pitch perhaps the 13 is in order.An induction tach is under $50 and easy to install and will work on any 2 stroke 2 cylinder.
An optical tach may work as well,speed by gps would be a big help.