Reply With QuoteAbout two months ago I asked the same.I didn't get an answer. Good question.
Why do they call em Cavitation Plates? It wouldn't seem to me that they are creating any cavitation.. So what's the deal?
RD
About two months ago I asked the same.I didn't get an answer. Good question.
RD, think about how much cavitation of the prop you would have if the boat climbed the 10deg. angle of the strut, the prop would blow out of the water, creating much cavitation, thereby the flaps on the back push the nose down to align the prop with the hull for a proper angle of thrust, plates down nose down, plates up nose up, too much up, uhoh. Hope this helps , hell I just drove 'em, didn't think too much about the scientific side of it, for every action there is an opposite reaction.
Riverdave,
From what I understand even the Outboad and I O motors have a cavitation plate. When the prop blows out Is't that called cavitating. So maybe the plate helps keep the water ehrer it belongs. (Dammit I don't know)
RD, i'm pretty sure pgf127 is right they were named that because they cut down on the cavitation. they should have called them anti-cavitation plates, like antipasta???
Originally posted by pgf127rt:
RD, think about how much cavitation of the prop you would have if the boat climbed the 10deg. angle of the strut, the prop would blow out of the water, creating much cavitation, thereby the flaps on the back push the nose down to align the prop with the hull for a proper angle of thrust, plates down nose down, plates up nose up, too much up, uhoh. Hope this helps , hell I just drove 'em, didn't think too much about the scientific side of it, for every action there is an opposite reaction.
PGF, http://free.***boat.net/ubb/smile.gif I'm an I/O guy so I believe the proper angle of thrust would be exactly inline with the angle of movenment.. I.E. 0 degrees. http://free.***boat.net/ubb/smile.gif
ThunderButt, O/B's and I/O's don't have a cavitation plate. What they have is a little tiny skeg above the prop (made of zinc) that is called a cavitation reducer. To be honest it does very little for cavitation and it actually has more to do with the Mercathode functions. (Making a flow of electric current in the water to attract corrosives to the zinc instead of the drive). Blowout, and Cavitation are two completely different things, but you are right Many people use Cavitation as kind of a "Slang" term for Blow out. (sounds better http://free.***boat.net/ubb/wink.gif )
RD
Thunderbutt,
you are correct. I/O's and outboards do have a cavitation plate. I don't know what the term is in the merc book, and I've heard it referred to a an anti-ventilation plate as well. Riverdave, I/O guy that he is, is referring to something completly different. In the old days before power sterring that little zinc thing with the small fin, used to be adjusted to help compensate for the tourque of the prop. Made steering a little easier, as well as being sacrifical.
Where's a Cav Plate on an I/O? You talking about that little flat section where the Lower and Upper Units come together? It seems to me that I read in the Merc owners manual that they referred to that worthless little fin as a "Cavitation Reducer." I could be wrong becuase It was years ago, but i remember thinking what the hell does that thing have to do with Cavitation? http://free.***boat.net/ubb/biggrin.gif Much like I'm thinking about the cav plates now.
RD
RD ,Old rigger answered your question already,I'm getting bored here ,so I put my 0.02 in too.The little thingy [sacraficial zinc,rudder http://free.***boat.net/ubb/wink.gif], aids straight line tracking, by offsetting torque effect caused by prop rotation.Depending on direction of prop rotation ,the rudder "thingy" has to be set the opposite direction of the pull by a few degrees.It has to be dialed in ,so it may take a few adjustment.The only thing I think of as a poor man's cavitation plate on a sterndrive unit is the Doelfin [not very effective].A cavitation plate is a beatiful piece of "low tech trimtab" on a performance [aka ***boat http://free.***boat.net/ubb/biggrin.gif]boat.
boat030, you are right on, as I thought about this topic and my reply I came up with the same answer as you, they are basically anti cavitation plates as you said just as the intended purpose of the whale tail for ob's and sterndrives. Don't know a whole lot about the last 2 but I would sure hate to try to run a flat without them, I have seen the results of some newbies who get in a flat and nail it without plating it and it's YEEEEEEEEHAW let's rodeo.
RD, interesting topic, you made this old flat nut dig to try to explain how we control them things, I knew how but had not really thought aout it in this light.
Posting Permissions