135hp outboard/advice on coarser pitch

[pcrussell50]

i spend most of my time on iboats talking and asking about my vintage, 1959 johnson 35hp super seahorse, so i don't get here to the prop forums too often...

...but this is totally different. it relates to my fun boat, a 16' sportster, [looks like a bass boat], with a 135 evinrude on it. this boat is really light, but i use it with a 19" pitch to tow skiers and wakeboarders, but in the winter, [southern cal], not so much with the watersports. so i got to thinking, it would be nice to play around with going fast in the winter when not towing skiers.

with the 19" pitch prop, and not towing anybody, it explodes right out of water and hits the redline with ease. so i tried a 21" pitch prop i have and it's only a little better. it will pull the prop right to the redline easily and not be near full throttle. because of this, i think it can pull more coarseness in pitch. i was thinking of trying a 23", but i really have no expertise. maybe even more? clueless here, thanks.

soo...in your experience, could i pull a 23" prop with this combo?
[135 evinrude, 750# boat with motor, flat'ish performance hull]

fwiw, even though i live on the ocean, this boat see only fresh water

-peter
santa barbara, ca

 

[Dhadley]

Re: 135hp outboard/advice on coarser pitch

"It hit's the redline with ease". Describe what the redline is.

 

[pcrussell50]

Re: 135hp outboard/advice on coarser pitch

"It hit's the redline with ease". Describe what the redline is.

the largest number on the tach is 6000rpm. the seloc manual says the power peak is 5500rpm. even with the 21 pitch, it goes effortlessly to 6000rpm once on plane, and I have to pull off throttle to keep the rpms between 5000 and 5500.

-peter
Santa barbara, ca

 

[Frank Acampora]

Re: 135hp outboard/advice on coarser pitch

Well, it's telling you it wants more pitch. Acceleration will not be as blazing but you may see an increase in top speed. On the other hand, top speed may remain the same with a lower top engine RPM. You won't know until you try.

 

[Dhadley]

Re: 135hp outboard/advice on coarser pitch

Are you sure the tach is correct? Is it set on position 6?

 

[Randybeall]

Re: 135hp outboard/advice on coarser pitch

Have you looked at what power that boat is rated for? I would bet it is about 90 horsepower. Yes, if you want more speed a 23"pitch would get you that if your truly pulling 6000rpm now. I suspect with a 135 on that boat your correct. Do be careful, overpowered boats can devolop nasty handling at speeds they have not been designed for or tested at.

 

[Dhadley]

Re: 135hp outboard/advice on coarser pitch

There's an interesting custom 4 blade on Ebay right now. Looks like you can get it in 23" pitch.

 

[pcrussell50]

Re: 135hp outboard/advice on coarser pitch

randy,

i had already looked at the hull before i bought the boat and the ID plate on it said it was rated for 115hp, so i'm hoping/expecting that the extra 20 horsepower is not obscenely overpowering it. i can see that it might be if your speculation about the 90hp max was right.

dhadley,

great tip! definitely the first order of business is to make sure that whatever rpm i base any future prop decisions on is the _actual_ rpm. when i get back to my boat, i'll check things out. fwiw, i couldn't help latching onto your suggestion of "position 6" for the tach. i ask, because this motor is a v4, so as long as "position 6" is not in reference to the number of cylinders, that should be good.

thanks all,
peter

 

[Dhadley]

Re: 135hp outboard/advice on coarser pitch

Yes, position 6 is what you want. The tach reads from the stator, has to do with pulses not number of cylinders.