Cavatation help needed please

Status
Not open for further replies.

jadssh

Petty Officer 3rd Class
Joined
Jul 9, 2009
Messages
80
Hello everyone. I have a 2011 Yamaha F-115 outboard on my 2011 Hewescraft 200. I noticed last year some paint starting to come off the OEM Yamaha prop, 13 1/2X17 prop. This year it started making a pit on the tips of my prop. The performance has not changed and the boat and motor operates great. Is this normal for a 3 year old prop, and is there any thing I can do to keep it from happening? Thanks everyone!
 

Attachments

  • photo232290.JPG
    photo232290.JPG
    380.6 KB · Views: 0
  • photo232291.jpg
    photo232291.jpg
    114.7 KB · Views: 0

jadssh

Petty Officer 3rd Class
Joined
Jul 9, 2009
Messages
80
Any one out there that can give me an idea about this and thoughts of whats causing it? Thanks guy's.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Cavitation usually occurs on the underside of the blade not the thrust side.
I wonder if you cruise a lot at an unusually slow or fast speed/rpm.
Blades look like for a heavy or hard to push boat.
What is the lightly loaded wot rpm and gps speed? This may help us tell how the prop is working.
 

Far2hip

Seaman
Joined
Aug 8, 2015
Messages
57
What an amazing coincidence, lol. I was turned on to trying out 4 blade props from one of my best buds that was seeing exactly what you are seeing here. It was suggested to him that there was something causing a slight air trail that was slamming shut at the tips of his blades causing this to happen. The suggestion was to try a 4 blade configuration to see if a different water capture trail would make any difference. Well, because none of his rpm/speed numbers were really out of whack he went out and put a equally matched pitch 4 blade Mercury Spitfire prop on the thing. It's only been since the beginning of this season and there is zero marks in those areas of the prop, but because he was so impressed with the increased speed, faster hole shot, and fuel efficiency from that Spitfire, he talked me into trying it on my little old 14' runabout with great success. But, there are far more talented brains about props in here than me. It was just a funny coincidence that my friend was having the exact same issue on the same motor!! Good luck
 

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
Do you use reverse gear very often?
Reversing off the trailer or using reverse as brakes?
 

jadssh

Petty Officer 3rd Class
Joined
Jul 9, 2009
Messages
80
Cavitation usually occurs on the underside of the blade not the thrust side.
I wonder if you cruise a lot at an unusually slow or fast speed/rpm.
Blades look like for a heavy or hard to push boat.
What is the lightly loaded wot rpm and gps speed? This may help us tell how the prop is working.

steelspike the WOT is at 5500-5800 at 32-35 mph off the gps. The prop is also of a cleaver design. Hope that helps.

Far2ship, that is a coincidence! I talked with a local prop guy who said the same thing on the 4 bladed prop, but he couldn't explain what caused the marks on the prop. I'm hoping some of the pros on here can identify it for me so i can fix the problem. I think it may be a OEM cheapo prop Yamaha put ont heir motors from the factory.

Fed, the only time I use reverse is around the dock and at a very low RPM close to idle speed. I never reverse off the trailer until I'm clear of the trailer and then its usually idle speed if i do. Hope that helps.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Your numbers say your slip is high. 22% at 5500 @ 32 and 19% at 5800 @ 35.
Your prop doesn't look like any Cleaver I ever saw.Actually it looks pretty mundane to me.
Does the prop seem to have any ventilation issues?
Is the anti vent plate(just above the prop) about even with the bottom.
If you want to try a slightly more sophisticated prop try a Solas Amita 17"
I think I read somewhere that Solas now supplies Yamaha props.
There are 3 models of sportsman; 200 at 1150 lbs.,ProV at 1700 and a proV/HC at 1875.
 

jadssh

Petty Officer 3rd Class
Joined
Jul 9, 2009
Messages
80
Thanks steelespike, thanks for the responses. The ventilation plate is even with the bottom. Not sure what you mean by ventilation issues???? At the tips of the prop right where the wear is, there is a shallow "spoon" type concave on the prop which some guys told me that was a cleaver type prop. I'm pretty dumb when it comes to props so i wasn't sure. I have a brand new spare still in the box that I kept after I sold my last boat. It is a 13 1/4 X 17 which is a 1/4 different than the one on my boat which is a 13 1/2 X 17. I was going to put that one on until i can decide what prop I want to go with. I have been told to go to a 4 bladed prop at a 13 1/4 X17 size and would really see an improvement. What are your opinions on that. Thanks again for the help!
 

jadssh

Petty Officer 3rd Class
Joined
Jul 9, 2009
Messages
80
Ok, I just went out to the boat to change out the prop to the new spare I had. While taking off the old prop I hand wiggled the hub nut before I took the cotter pin out and it was so loose i was able to move it left to right against the pin. I removed the pin, and was able to unscrew the nut by hand with no force at all. The manual calls for that nut to be torqued to 40.6 ft. lbs. After I put the new prop on and torqued it down, there was no way i could even come close to moving it with my fingers.

My question is the obvious. Should that nut have been that loose? It seems to me that when its torqued properly and the pin is in place, unless the pin breaks I don't see any way that nut can come loose????? Now having said that, could that have been the cause of the marks and decay of the prop? Thanks.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
I don't think the loose nut would cause any problem except if it got loose enough to fall off.
We used to call ventilation, cavitation.
Ventilation is when the prop gets fouled with air loses its grip on the water,motor revs and the boat slows.
Sometimes this can be from the motor being too high ,a poor prop or being trimmed up too much.
Rough conditions may trigger some venting or extreme maneuvers at speed.
Do a search for cleaver props I think you will see yours isn't a Cleaver.
A 4 blade prop can improve hole shot, stay on plane easier at reduced throttle,
seem smoother and handle better around the dock.
Usually suggested to reduce pitch 1" when going to a 4 blade.You may lose a little top end.
You might see if you can get a Merc "Spitfire" for your motor.These exchange pitch for pitch
and are said to perform very well without the 4 blade minor losses.
 

jadssh

Petty Officer 3rd Class
Joined
Jul 9, 2009
Messages
80
Thanks for all the help steelespike. I did google the cleaver prop and your right, mine is no where near that. Don't know why the prop shop told me that the prop I had was a cleaver prop. I test drove the spare prop I had which was a 13 1/4 X 17 today. I think it performed much better than the OEM 13 1/2 X 17 I had on there. RPM's were higher and sharp turns had a better bite to them. Better acceleration and picked up a little speed. I think I will keep that one on until I put her away for the winter, then decide between a 3 blade or 4 blade over the winter. I am going to assume for now that the wear on the old prop may be caused by a cheap prop??
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
If you get us the lightly loaded wot rpm and gps speed we may be able to confirm the details of your prop.
Its important that your motor can operate within its wot rpm rating. Once we establish that you can operate at
what ever throttle setting suits you.You may want to fine tune your setup.
 

jadssh

Petty Officer 3rd Class
Joined
Jul 9, 2009
Messages
80
Thanks steelepike. I did record several RPM's and Speed yesterday while I was running my spare prop. The prop is a 13 1/4 X 17 Aluminum prop. Here is what I recorded... 4400 RPM-27.1 MPH.... 4700 RPM-28.9 MPH....4800 RPM-29.5 MPH....5000 RPM-31.7.....5500 RPM-34.8 MPH.....6000 RPM-37.6 MPH.

These readings were taken yesterday on a very calm day. Water was calm and all reading were taken the same direction on river. Very little to no current. The boast was lightly loaded with just me and my black lab in the boat. I might also note that on my old prop, 13 1/2 X 17, I was not able to reach 6000 WOT. It got me close, 5800 I believe. Thanks a million steelespike for helping me out. If you need any more information let me know. John
 

jadssh

Petty Officer 3rd Class
Joined
Jul 9, 2009
Messages
80
I forgot to tell you steelespike, I have a top on my boat, and that was up when I ran these readings. I have never had the top off, so I guess there would be some drag from the top being on. Thanks.:joyous:
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
The top very likely could slow you some.Might be interesting to see without the top.
Speed is better and and max rpm is right on.Slip is still a little high.
Could you send a picture of the prop and anti vent plate in relation to the bottom.
How was the hole shot? Any ventilation issues?
Sometimes high slip is simply the tach reading a little high.Typical slip is 10 to 12%
As you reduce throttle slip tends to go up.Heavier or hard to push boats will tend to have higher slip.
 

jadssh

Petty Officer 3rd Class
Joined
Jul 9, 2009
Messages
80
No Title

Here you go steelespike, Hole shot was very good, just like my old prop. Ventilation issues not sure, not familiar with what to look for while operating boat. Nothing really seemed out of the ordinary. That round rudder looking thing under the ventilation plate is angled just a little. I'm assuming it has something to do with counter torque or something. Let me know if you need any other photos or information. Thanks. John
 

Attachments

  • photo232401.jpg
    photo232401.jpg
    83.6 KB · Views: 0
  • photo232402.jpg
    photo232402.jpg
    85.1 KB · Views: 0

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
The "rudder thing" is a sacrificial anode to control any Electrolysis and can be adjusted to control torque steer as you suggested.
If you only boat in fresh water the anode will last a lifetime.
Ventilation is pretty obvious waves,sharp turns. powerful hole shot, trimming up too far may trigger ventilation.The prop will lose its grip may be momentary or you may have to reduce throttle to get grip back.
you probably don't have any venting going on. I would say your set up pretty well.
You could raise the motor one hole to see if you can get a little more speed.
Though it seems really good as it is.
 
Last edited:

jadssh

Petty Officer 3rd Class
Joined
Jul 9, 2009
Messages
80
Thanks steelespike. I'm happy with the speed and the way the boat handles. Especially with the prop I just put on it, it's a cheap spare new out of the box I had. I was just worried that my setup was wrong or something because of the damage to my old prop with just 60 hours on it. I'm going to use this prop until i have to put her away for the winter, then I'm going to buy a more quality prop and use the one i have on now as a spare.

So to rack your brain just a little more steelespike, do you suggest I stay with a 3 bladed prop at a 13 1/4 X 17 or try out a 4 bladed prop that a lot of people have recommended due to its maneuverability and all? I would want to try something that is equivalent to the size prop I have on there now. Thanks John
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Usually suggested to reduce pitch one inch when going to a 4 from 3.
For the investment a 4 blade will likely have the most affect.Improved hole shot,less vibration,stay on plane better at reduced throttle.
You also may note the improved handling around the dock.It should resist ventilastion.Unfortunately
The trade off is a little less top end.
If you can find a Merc Spitfire for your motor they exchange pitch for pitch and are said the improve overall performance even on boats with exceptional, performance
 
Last edited:
Status
Not open for further replies.
Top