Best prop on an outboard

[ontheplane]

Hi,

As everyone knows (maybe) on your outboard you should have the right prop for the job fitted.

Assuming that this is the prop that allows the engine to spin up to (but not over) max revs with the standard load aboard the boat that's simple.... However if you have a simple tiller steer outboard with no rev counter - how are you supposed to know what rev's the engine is pulling - and thus if you have the right prop??

Can you get a cheap clip-on rev counter to do some tests or has no-one seen such a device?

 

[Davy_S]

Can you get a cheap clip-on rev counter to do some tests or has no-one seen such a device?

Ok, this is not a perfect answer, as no one else has replied I will give you my opinion. My second boat is a small tiller steered fishing boat with a Honda 25 hp motor. To be honest I use this boat the most, I go fishing and swimming and visit Ithaki etc about three days a week.
Regarding rev counters, i believe there is one called a tiny tac or similar that registers vibtration and pulses, not tried it dont know.
What I do is this, I run a 91/4 X 12 inch prop (standard) and check with GPS the speed. In my case I get 19 knots, I tried a 11 inch prop, acceleration was similar, top end 18.5 knots, so I stuck with what I had. As a rough guide for ever inch of pitch you gain or lose 200r pm, ie increase pitch you lose 200 rpm , decrease pitch, you gain rpm. To get your requirements in a small tiller steered boat you need to be exact, only two of us use ours most of the time, if we took two extra friends on a longish trip, we would need to decrease the pitch or we would be overpropped for a small boat.
Hope this makes sense!

 

[VicS]

i believe there is one called a tiny tac

Tiny-Tach see http://www.tinytachuk.com/

Senses pulses in one of the HT leads.

 

[Tremlett 15]

Tiny-Tach see http://www.tinytachuk.com/

Senses pulses in one of the HT leads.

also see

http://enmco.thomasnet.com/viewitem...meters-pt16-tachometer?&plpver=1001&forward=1