Propeller selection for 6 Hp 4 str

gada

Recruit
Joined
Sep 3, 2008
Messages
4
Hi All,
I bought a 6 hp 4 stroke Tohatsu as a second motor. After 10 hours of break in, I noticed that it does not respond to throttle after ? turns. The motor noise increases a little, but speed (5,5 kt max) does not change. My boat is 15? long fiber v-hull and usually 700 - 900 lbs when loaded. It can reach up to 17-18 kt with my other motor which is an 18 hp 4 stroke Tohatsu. As there is not much space on my transom, I cannot install both motors at the same time; therefore I need the 6 hp also for traveling up to 2-3 miles away.

In order to protect the 6 hp motor from being strained and reach a better max speed, I think I need to change the propeller. The original is 7,8 x 8. What kind of propeller should I use? Is 7 pitch enough, or should I go to a 6 pitch special heavy load propeller with extra large blades?
Thank you in advance for your comments,

Best regards,

Murat
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Propeller selection for 6 Hp 4 str

Without a tach reading you shouldn't change props.Could be bad for motor health.5.5 speed seems close to me.Careful weight distribution may help. When running alone a tiller extesion so you can sit in the middle seat may help.
I would think with that load a 7" pitch would help.But without rpm figures
its a crap shoot.With that load I wouldn't expect much speed change but the motor would probably be happier.
 
Top