Cavitation on cornering

[Wakeboarder Tom]

Guys - this is probably a very simple question to answer, but I have no clue! When cornering hard when driving any boat at WOT and you get cavitation and speed reduces, is it best to back off the throttle and let the prop bite again, or is it OK to let the prop spin until it bites again?<br /><br />Whatever boat I owned, I always managed to get this to some extent. (We drive on a small lake and I love tearing through the wake and the chop to throw the boat (and wife!) about a bit!) I always back straight off the revs when this happens, but looking on a couple of recent threads, people keep the revs on and wait for the prop to bite again.<br /><br />Which is correct or are neither???

 

[Ron G]

Re: Cavitation on cornering

I always trim down and keep on rolling.may be the wrong way but it works for me in really sharp turns may produce some sliding.

 

[Texasmark]

Re: Cavitation on cornering

Depends on your setup. In my instance my current rig does not blow out (completely) and holds a reasonable couple hundred rpm increase. That's ok for me because I'm playing and know that if I wanted to, I could eliminate the problem; but I don't want to. Besides, I like to feel it catch on the pullout and pull the rpm's back down......like the ported prop I had on my last boat...I'd blow outta the hole and she would be a howling and next thing you knew, the water pressure got high enough to seal the holes and the prop bit and it was just like you shifted gears. Really cool...for me.<br /><br />Mark

 

[Texasmark]

Re: Cavitation on cornering

Another thing, my current tin lizzie has a piece of angle aluminum running full length right down the keel for damage protection and to cover where the center weld is. I'm sure that some of my cavitation is caused by that as it runs all the way to the transom. But that's ok<br /><br />Well this makes a perfect skeg and when you lay her over, she lays over....doesn't slike like a john would.<br /><br />Mark

 

[Dunaruna]

Re: Cavitation on cornering

VENTILATION! not cavitation.

 

[Wakeboarder Tom]

Re: Cavitation on cornering

Sorry!<br />Like I said - no clue!<br /><br />Why does it do this anyway?

 

[MajBach]

Re: Cavitation on cornering

I was just about to add: wouldn't this be ventilation?<br />I am by no means an expert on the forces involved, but when I used to experience this, I always backed off on the throttle. I kind of relate it to leaving the ground in a car or motorcycle and not backing off on the throttle. I also figured that there would be quite a surge of force to the drivetrain and transom when it did bite again. <br />Even though it's caused for different reasons from cavitation, wouldn't the air meeting the prop still be damaging?<br />Once I installed a hydrofoil, this problem disappeared for me.

 

[Dunaruna]

Re: Cavitation on cornering

Ventilation, is when air from the surface is introduced to the prop. That's why an ANTI-VENTILATION plate (AV plate) is fitted to try and reduce this. <br /><br />Cavitation is much more complicated, but basically it is tiny air bubbles that cause symptoms similar to boiling - they can cause prop damage.<br /><br />Ventilation is much more common.

 

[Texasmark]

Re: Cavitation on cornering

Duna....Interesting reply and I guess I will agree to some extent. My Webster's New College Dictionary associated cavitation with propellers and under ventilation it just mentions "....allows fresh air in.....".<br /><br />First of all I had a Chrysler 85 hp without thru hub exhaust...like in '71. They had a real funny looking alum prop on the thing that had a pretty good overhang on the front of the blade just as it left the hub. It did cavitate and after a few hours of running there were these little circles about a half inch in diameter that developed in that area where the paint disappeared and little pits developed in the aluminum.<br />-----------<br />Then I think in a tight turn you are exposed to both as the hull is producing turbulence in addition to the awkward angle the engine is exposed to which helps it to ventilate.<br /><br />Where I grew up we always called the plate anti-cavitation. Guess we didn't know any better. We never heard of the word ventilation....with respect to the marine environment till the advent of the bass boat. Grin<br /><br />Mark