6hp motor kinda sluggish after changing boats

[ETHAN5438]

I had my 1977 6hp evinrude on a 12 ft jon boat and it went well. The I got a 11ft semi v hull richline and my top speed is only about 10 mph is there any way i can get more out of my motor with a change of prop?

 

[Sea Rider]

To play with prop pitches professionaly need to install an induction tach go for a wot run solo boating on flat calm water cond and report the achieved max wot revs. Compare to the factory min-max wot rpm range to check if the motor is revving around the lugging rpm side which is bad. A less pitch number will bump the wot rpm higher along bettering the top end speed. What's the current prop number stamped on the body or blade ?

Happy Boating

 

[ETHAN5438]

To play with prop pitches professionaly need to install an induction tach go for a wot run solo boating on flat calm water cond and report the achieved max wot revs. Compare to the factory min*max wot rpm range to check if the motor is running around the lugging rpm side which is bad. A less pitch number will bump the wot rpm higher along bettering the top end speed. What's the current prop number stamped on the body or blade ?

Happy Boating

right now it has the factory (i think its factory) 8x7p

 

[Sea Rider]

right now it has the factory (i think its factory) 8x7p

Must be 100% sure on what you have and go from there maximizing a less prop pitch. Without a tach will be a wild guessing determining at which wot rpm the motor is reving at at full throttle powering the new boat.

Happy Boating

 

[racerone]

Check the power output of the motor.------Most shops used to have test props for running in a proper sized tank.----Motor should run full throttle and a specified RPM to determine this.---If motor does NOT reach proper RPM there is something wrong.

 

[ETHAN5438]

this is my prop right now

 

[ETHAN5438]

To play with prop pitches professionaly need to install an induction tach go for a wot run solo boating on flat calm water cond and report the achieved max wot revs. Compare to the factory min-max wot rpm range to check if the motor is revving around the lugging rpm side which is bad. A less pitch number will bump the wot rpm higher along bettering the top end speed. What's the current prop number stamped on the body or blade ?

Happy Boating

You are talking about the tachometer where you wrap the wire around the spark plug?

 

[racerone]

Some shops use TEST PROPS.------They do not even look close to a regular prop.------Google that if you are unsure of this simple item

 

[ETHAN5438]

Must be 100% sure on what you have and go from there maximizing a less prop pitch. Without a tach will be a wild guessing determining at which wot rpm the motor is reving at at full throttle powering the new boat.

Happy Boating

on youtube i saw someone put a 8.25 with a 5p on a 14ft semi v hull and got 12 mph

 

[Sea Rider]

You are talking about the tachometer where you wrap the wire around the spark plug?

Yes that type of tach, test props are only good to run motors at max wot rpm while being tested on a test tank, will not push a combo on water. Each boat/motor has it's own installation forget all about what others post on YouTube...If your motor is a 1977 model with non through hub exhaust, Iboats site only states just 3 available props. Check..

http://boatpropellers.iboats.com/Evi...t_id=721023611

Would recommend a Hardline Hour/Tach model : HR-8061-2 Check Iboats, Amazon.

Happy Boating

 

[Sea Rider]

So that's a non through hub prop, right ? If motor runs as a champ at all throttle setttings, only needs a prop maximization. But if isn't known at which max wot rpm the motor is revving up how can you determine how much less prop pitch the motor needs to improve its water performance powering the latter boat.

Have discovered that same motor powering 2 different type of boats will not work same, boat lenght, hull shape, drag coefficient, trim, motor height and deck weight distribution accounts exponentially for that to happen.

With respect to the current prop, if newer less pitch props are non available, send that prop to a prop shop, have it repainted along a nice 2 less pitch rework from current factory delivered prop pitch..

Happy Boating

 

[ETHAN5438]

So that's a non through hub prop, right ? If motor runs as a champ at all throttle setttings, only needs a prop maximization. But if isn't known at which max wot rpm the motor is revving up how can you determine how much less prop pitch the motor needs to improve its water performance powering the latter boat.

Have discovered that same motor powering 2 different type of boats will not work same, boat lenght, hull shape, drag coefficient, trim, motor height and deck weight distribution accounts exponentially for that to happen.

With respect to the current prop, if newer less pitch props are non available, send that prop to a prop shop, have it repainted along a nice 2 less pitch rework from current factory delivered prop pitch..

Happy Boating

It runs decent it sounds like it hits a good spot in its revs at wot but i'm not for sure on that because i'm just going by sound. the boat does have a good amount of drag probaly the motor is too small for the boat and ill just have to suck it up

 

[Sea Rider]

That motor needs to rev at wot inside its wot rpm range factory stated which you can't possibly tell by simple ear tach no matter if having a musician ear. Ideal would be to rev around its max wot rpm range. I've done dozens of prop maximizations on different boat types with spot on results. I'm called locally the wizard of prop maximization for under powered motors, but if you want to keep boating that way it's entirely up to you. You will never know what you are missing by not going straight for a prop maximization.

Won't break any world record with said motor, but will push/plane that combo better than with current factory delivered prop and that was what you were looking for on your post.

Happy Boating

 

[ETHAN5438]

That motor needs to rev at wot inside its wot rpm range factory stated which you can't possibly tell by simple ear tach no matter if having a musician ear. Ideal would be to rev around its max wot rpm range. I've done dozens of prop maximizations on different boat types with spot on results. I'm called locally the wizard of prop maximization for under powered motors, but if you want to keep boating that way it's entirely up to you. You will never know what you are missing by not going straight for a prop maximization.

Won't break any world record with said motor, but will push/plane that combo better than with current factory delivered prop and that was what you were looking for on your post.

Happy Boating

Okay I’ll go buy a tach and when it’s warm enough I’ll see what it says

 

[QBhoy]

Also check the height of set up and/or shaft length is suited to the new boat.

 

[Sea Rider]

Okay I’ll go buy a tach and when it’s warm enough I’ll see what it says

Way to go, report your finding when the weather gets warmer and will go from there propping the motor right.

Buy a Hardline Hour/Tach HR-8061-2 model, are less than $ 30, check Iboats, Amazon for them.

Happy Boating

 

[82rude]

I have a 1974 6hp Johnson that I use as a kicker sitting beside my 60 etec.A quite stellar motor.Good luck with yours.