Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Prop choice for a 25hp 4-stroke Nissan

Posted by BAY2SAV on 07/07/08 - 7:37 AM
#1

I've been wondering how to squeeze an extra mph or so out of my 2002 Nissan 25hp 4 stroke on my 13 Sport. The max rpm for this engine is 5500 rpm and currently has an aluminum 3 blade 9.6X13 prop. The gear ratio is 1.92.

I've been looking at a 10X14 4 blade stainless steel prop. I don't need to worry about the hole shot capability - just want to increase my cruising speed. I don't have a tach currently installed.

Any suggestions would be appreciated.
Thanks,

Posted by kamie on 07/07/08 - 5:24 PM
#2

Denny,

Unless you know where you are, you don't know if you have improved anything. Without a Tach you don't know how efficiently the engine is spinning the current prop. Do you have plans to add a tach to your current setup?

Posted by BAY2SAV on 07/08/08 - 9:23 AM
#3

Yes, I intend to install a tach to the boat - but probably not until later this year. I have to admit, I was looking for an easy way out - hoping someone would have the same boat/motor combo from which I could guage possible prop sizes and number of blades.

I will go with the recommended procedure of using the tach, but it'll have to wait until later. Just alittle impatient that's all.....

Posted by Tom W Clark on 07/08/08 - 11:10 AM
#4

A tachometer is inexpensive and very easy to install. Why wait?

You can also buy a Tiny-Tach, less expensive still:

http://www.tinytach.com/tinytach/inde.../index.php

Edited by Tom W Clark on 07/08/08 - 11:12 AM

Posted by Tom W Clark on 07/08/08 - 11:19 AM
#5

To answer question about the number of blades, I would stick with a three blade prop. Stiletto makes the Triad 3.0 which will fit the Tohatsu 25 four stroke. Propeller diameter is 10-1/8" x anything from 10" to 14".

You will probably want a 12" or 13" pitch.

Posted by BAY2SAV on 07/09/08 - 10:05 AM
#6

Thanks Tom,

I have a Faria Tach and a Faria depth meter that I plan to install on the console. Just have not gotten around to it. I plan to get all my electronics (bow light and stern light rewire, tach and depth meter) done when I pull the boat next time.
I have an aftermarket stern light base that was mounted in the starboard rear that is pulling thru that I also need to deal with.
Then I'll worry about the prop......:)

Thanks,