Author Topic: need prop advise (Read 20709 times)

Wesley Ellet · « **on:** March 06, 2016, 01:38:49 PM »

Took my newly restored cv16 out for ts first run today. I have a problem though. With the prop that is on it, it will cavitate bad and wont come up on plane. I am told I need more pitch. I am running a johnson 140 hp outboard. (1977 model) the prop that is on it has no markings. It had alot of nicks in it but I cleaned it up. Any advise would be appreciated.

Hyperacme · « **Reply #1 on:** March 06, 2016, 01:50:24 PM »

David CVX-16 would be the guy to ask ...
You could search his posts for prop info.

dorelse · « **Reply #2 on:** March 06, 2016, 02:18:34 PM »

A 140 on a CV-16 should get up on plane with almost any prop....you sure the motor is running right? Got the trim all the way in or out? That's a lot of motor on that hull so I'd expect it to plane with a paper prop on it...

Rich_V174SS · « **Reply #3 on:** March 06, 2016, 02:27:06 PM »

If it's cavitating the hub in the prop is probably slipping, evident if you're engine rpm is racing and the boat doesn't go anywhere.

David CVX-16 · « **Reply #4 on:** March 06, 2016, 03:49:04 PM »

I agree with the above. Any prop should bring the boat up on a plane. Most likely a slipping hub. Scratch/mark the metal cylinder/inner liner to line up with the prop and see if the markings line up or have moved after testing the prop. A prop shop would also be able to determine if the rubber hub slips.

With props so cheap, about $125 for a new aluminum OMC SST II, just throw away the old prop. A hub repair might run $75.

still_fishin · « **Reply #5 on:** March 06, 2016, 05:18:15 PM »

Maybe he has a chopper style prop on it. I'm not trying to compare my Intimidator to his CV bit when I tried a merc chopper on my over powered Intimidator all that prop wanted to do was cavitate. I could feather the throttle for about 15 to 20 seconds to get it up on plane but that was no fun.

Wesley Ellet · « **Reply #6 on:** March 06, 2016, 05:30:44 PM »

Quote from: David CVX-16 on March 06, 2016, 03:49:04 PM

I agree with the above. Any prop should bring the boat up on a plane. Most likely a slipping hub. Scratch/mark the metal cylinder/inner liner to line up with the prop and see if the markings line up or have moved after testing the prop. A prop shop would also be able to determine if the rubber hub slips.

With props so cheap, about $125 for a new aluminum OMC SST II, just throw away the old prop. A hub repair might run $75.

It felt to me like something was slipping but a passenger said i would push air when it would happen. I have never owned an outboard so I'm not sure. The prop is not in good shape any way so a replacement ss prop is immanent any way. What pitch would you recommend for speed?

Wesley Ellet · « **Reply #7 on:** March 06, 2016, 05:50:15 PM »

Quote from: still_fishin on March 06, 2016, 05:18:15 PM

Maybe he has a chopper style prop on it. I'm not trying to compare my Intimidator to his CV bit when I tried a merc chopper on my over powered Intimidator all that prop wanted to do was cavitate. I could feather the throttle for about 15 to 20 seconds to get it up on plane but that was no fun.

I would kind of feather i back and get closer but then I got nervous about possible damage if it was slipping. Arn't most chopper props marked? this one has no marks on it.

still_fishin · « **Reply #8 on:** March 06, 2016, 07:04:29 PM »

Chopper

Wesley Ellet · « **Reply #9 on:** March 06, 2016, 07:36:01 PM »

Quote from: still_fishin on March 06, 2016, 07:04:29 PM

Chopper

It is definitely not a chopper prop. it does not have that much pith or blade. Would that prop work on a 140 hp johnson?

Maclin · « **Reply #10 on:** March 06, 2016, 07:36:28 PM »

Is this engine new to this boat? Just wanting to check the mounting, make sure the prop is all the way in the water. The anti-cav plate should be rignt at or just above the keel. Also just asking if it could be a short shaft engine or not. Or if it is mounted on a setback bracket and could be set a little too high.

If mounted properly and it is the correct shaft length then sounds like a prop issue with the hub or bad condition of the blades or both.

David CVX-16 · « **Reply #11 on:** March 06, 2016, 08:10:47 PM »

Quote from: Wesley Ellet on March 06, 2016, 07:36:01 PM

Quote from: still_fishin on March 06, 2016, 07:04:29 PM
Chopper

It is definitely not a chopper prop. it does not have that much pith or blade. Would that prop work on a 140 hp johnson?

Do you pull skiers? If so, go with a 19 pitch prop, either aluminum or a stainless steel OMC SST II.

If you are going for speed, a good prop is a 22" OMC Raker. For light loads, the 22" pitch should work. For heavy loads, such as four passengers, go with a 20" Raker. Rakers are not good for pulling skiers out of the water.

Hyperacme · « **Reply #12 on:** March 07, 2016, 10:15:05 AM »

A 1977 140 HP J/E would be power head rated so would be about 115 HP prop rated ...
My guess would be as Dave said ...
20P for heavy loads or skiing / tubing.
22P for speed .

Some prop shops or boat dealers will let you try a SS prop before buying one.
Or just buy and sell different one on Craigslist until you find one that works for you.
That would be the best / cheapest route ...

Thanks to Dave CVX-16 I tried many different props on my CV, best one for my needs was a 22P ...

Hyperacme · « **Reply #13 on:** March 07, 2016, 10:26:02 AM »

Having trouble finding Dave's write up on prop testing on this forum ...
But this one is a good read ...

What is Fastest Prop for CVX-16 w 115 HP OMC?
http://www.classicglastron.com/phpbb/viewtopic.php?f=103&t=8603

Oldfishguy · « **Reply #14 on:** March 07, 2016, 11:07:20 AM »

I think we are going to need to see a picture of this newly restored machine. (We love pictures!) And with that motor on it I believe it will reach speeds that are kind of scary.

David

Hyperacme · « **Reply #15 on:** March 07, 2016, 12:07:56 PM »

Pictures and info on how your motor is set up (height on transom) ...

Wesley Ellet · « **Reply #16 on:** March 07, 2016, 12:14:05 PM »

Not sure but I think I found the problem. I see rubber and metal shavings in there. Found the no. It says 12 3/4X21m. I took everybodys advise and I think a 20 raker is probably what I want except I cant seem to find a good used one and a new one is around $500 to $700.

Wesley Ellet · « **Reply #17 on:** March 07, 2016, 12:26:34 PM »

I can send a rear view later

Rich_V174SS · « **Reply #18 on:** March 07, 2016, 12:34:53 PM »

Melted rubber = slipping hub

Plugcheck · « **Reply #19 on:** March 07, 2016, 03:43:30 PM »

It appears that there are no splines left on the hub, hopefully the splines on the output shaft are OK. They should be, much harder material. New prop and hub are in order, likely cost $90.00+ to rebuild the prop, so new probably be a better way to spend the funds. The surface and profile of props are a combination of both art and science, far beyond what I know about them, but I will say this, when one gets damaged even slightly, it can really cause issues. A small chip can cause cavitation and vibration. In a nutshell, I'm personally responsible for chewing up a few props over the years, so I've learned that having them rebuilt is not as smooth functioning as a new one, maybe you MN folks have better prop shops, but the two I've tried had mixed results.