Propellers

[bowl]

I have a 12-1/2 ×15 propeller.
When i google ...it mostly comes up with johnson/ evinrude 12 -1/2 x13 for 50 hp johnson
...will the other prop be ok. :cheers:

[jedgpz]

I dont know much about props but have just replaced one on my boat and 2 pitch difference on a prop is a lot from what I was told.
a lower pitch increases acceleration (ie gets the boat out of the water quicker) . where as a higher pitch will give you a higher top speed but will take longer to get the boat out of the water.
I shop I went to was happy for me to exchange the prop if I was not happy with boat performance provide it was not damaged in the testing process.
Cheers Jed

[Mattblack]

I've heard good things about The Prop Shop in Bayswater.

[skronkman]

The correct prop for your boat and motor is the one that allows you to get closest to your motors maximum revs at full throttle (and best trim) without going over. The lower the pitch the more hole shot but you might have to watch that you don't over rev (rev limiters now so you'll hit cut out). If you over prop then then you won't be able to get to max revs and have poor hole shot. There is no easy way to figure this out with out trying it because it's boat and motor specific. Some places will allow you to try a prop and then exchange it if it's not a good fit. Prolly set you back $700 for a new one though. If you're buying second hand then you gotta guess and hope.

Know what your motors max rpm is. Know what your current prop pitch is and what is your current max rpm. If you're under your max rpm then subtract an inch of prop pitch for every 150rpm you're under max. It's a rough guess. Do the opposite if over rev but this is more difficult to judge.

Ask the prop shop specialists what they would recommend for your boat and motor and use that as a guide.

My preferred way to do it is to prop a boat for max recommended revs (maybe even slightly over) unloaded. Then when you're loaded up you'll be close to best setup. If you're not planning on pulling skiers or climbing 4 meter plus swell off shore then you won't need the extra torque (hole shot) at the expense of speed and efficiency.

[Bugatti]

I have a 12-1/2 ×15 propeller.
When i google ...it mostly comes up with johnson/ evinrude 12 -1/2 x13 for 50 hp johnson
...will the other prop be ok. :cheers:

bowl, just a question, is your current propeller the right one and you are trying to find one exactly the same but having difficulty finding one to buy on Google as a cost effective way instead of a retail priced one at a prop shop (if you know what I mean) , , , , or , , , , it's not the right one for your boat and looking for one that is better suited?

Either way, good luck with it bowl.


ps. I don't know much but I know , , , , don't get one of these propellers.

The correct prop for your boat and motor is the one that allows you to get closest to your motors maximum revs at full throttle (and best trim) without going over. The lower the pitch the more hole shot but you might have to watch that you don't over rev (rev limiters now so you'll hit cut out). If you over prop then then you won't be able to get to max revs and have poor hole shot. There is no easy way to figure this out with out trying it because it's boat and motor specific. Some places will allow you to try a prop and then exchange it if it's not a good fit. Prolly set you back $700 for a new one though. If you're buying second hand then you gotta guess and hope.

Know what your motors max rpm is. Know what your current prop pitch is and what is your current max rpm. If you're under your max rpm then subtract an inch of prop pitch for every 150rpm you're under max. It's a rough guess. Do the opposite if over rev but this is more difficult to judge.

Ask the prop shop specialists what they would recommend for your boat and motor and use that as a guide.

My preferred way to do it is to prop a boat for max recommended revs (maybe even slightly over) unloaded. Then when you're loaded up you'll be close to best setup. If you're not planning on pulling skiers or climbing 4 meter plus swell off shore then you won't need the extra torque (hole shot) at the expense of speed and efficiency.

And skronkman, I remember some jargan from the dealer when I bought my motor, and can't remember what they said, but you've explained it quite well, that even I can understand.

And you are right, they knew my boat, knew the motor I was buying and Barding Bardang , , , , they got it right the first time. Beats me how they do it but they do.

But the question , , , , over revving is bad, no doubt but I vaguely remember something about if it is full throttle but not close to its max revs that is bad too, can do damage to the motor. Is that right?

Cheers, Bugatti

[Wolly Bugger]

The prop on my motor was standard until I bent it and bought a spare.

However it gets out of the hole as fast as a rabbit with a ferret on it's tail. It hits about 37 knots. So I am not complaining.

[skronkman]

Bugatti, yes that is correct. The analogy mostly used is like trying to drive your car uphill at a low speed in a high gear. The motor don't like it and we can all feel that pretty obviously if we try it (if you can drive a manual of course!)