Cavitation plates

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J Solinger

Well-Known Member
Joined
Sep 5, 2004
Messages
284
What does the cavitation plate do on a model out board engine? I'm just pondering if it is needed for boat control or to spare other boats from the prop.
 
What does the cavitation plate do on a model out board engine? I'm just pondering if it is needed for boat control or to spare other boats from the prop.
When I added one, I totally stoped my tunnel from blowovers. I actually made one, and bent the back end down some, and I was able to remove weight from the nose of the hull. I don't think they are legal in organized racing..I don't race, so I'm not sure, but I think that is what Joe Monohan told me...maybe that was just for the stock class tho.
 
What does the cavitation plate do on a model out board engine? I'm just pondering if it is needed for boat control or to spare other boats from the prop.

Good topic Joe. I wish I new the what to say there purpose was. Becides to hold the water pickup and to keep the prop spray (roostertail) down. I can say that in full size outboard hydroplane racing that we pretty much do not use them anymore.
 
Has everything to do with cavatation.(propeller hookup).. It also can make a ton of unwanted lift if not careful.

It seems so strange that a devise that does not run in the water can cause the prop to either load or unload. But when you think of it the water that comes off the prop is still attached to the water the boat is running over. You have to keep this in mind as you ponder the cavatation plate.

Grimracer
 
I am not a fan of cavitation plates. Yes they do collect water off the prop and that force can be used to hold the nose down. Not the way I would choose but it does work for some. I narrow or remove them and basically use them for holding water pickups and pipe mounts. In a corner if the plate touches the water you will get lift you may not want. Have yet to see any hydros monos or cats adding them for any purpose. A good propeller shouldn't need the assist. In full size application drag outboards use some that are almost prop tunnels. Once on plane they have little effect. Just added drag in my opinion.
 
I never removed them from my o/b's, but I always thought that the cavitaion plate was intended for subsurface props to reduce the amount of air getting sucked under by the prop and causing cavitaion. So on the surface drive set-up we all run on our tunnels it is probably of little value.

chunk
 
So is removing them on tunnel hulls and adding more lead in the front a better way to set up a boat? Does it have an effect on proper steering?
 
So is removing them on tunnel hulls and adding more lead in the front a better way to set up a boat? Does it have an effect on proper steering?

It is not quite that simple. If your hull is consistently blowing over correcting it with a wheelie bar strategy is one way. Adding weight and or a combination of just triming the motor angle will work also. Then consider the lift is aerodynamic and maybe try foils or small wings. Some cowlings lift more than they give down pressure. Setting the motor and prop back can reduce blowing over also. Some props lift differently. Many options to try and use the method that gives you the cornering and handling you like. Testing testing testing is the magic bullet.
 
I am not a tunnel guy in model boating but i would think it woud have a profound affect on handling at high speeds . I'm not sure if model tunnels go fast enough for the plate to have an effect but I would think they would , kind of like a tunnel tab on a full size tunnel boat .
 
I once lost a piece of the cavitation plate and i knew something was wrong with the boat....

I don,t know exactly what it does, but I do know one thing, the boat will handle different and will not perform well....

Ronald
 
I was just wondering if Anyone has re-moved a cav. plate and tested it like this . A OS would be a good unit to test this with or for that matter a Lawless lower also . I don't have any lawless just OS & K&B . I would hate to wreck a good lower for bad results . Anymore info on this would be great . I will look into trying my OS without one sometime coming up for sure

Thanks Ed
 
Removing the cavitation plate will make it hard to handle. I set all my tunnels with o deg angle add to the cavitation plate and add weight to make the hull ride flat. In doing so I gain speed and Handling.There are a lot of things that need to be considered Here. Hull design, Engine Power, Prop, Weight, lower unit. I Have ran many hulls over the years and can tell you that the Leecrafts, Hornets, Shamon, Warhead, Proglass Will run and handle better with a longer and wider Cavitation Plate Not taking away from it.

See ya Jimmy
 
Removing the cavitation plate will make it hard to handle. I set all my tunnels with o deg angle add to the cavitation plate and add weight to make the hull ride flat. In doing so I gain speed and Handling.There are a lot of things that need to be considered Here. Hull design, Engine Power, Prop, Weight, lower unit. I Have ran many hulls over the years and can tell you that the Leecrafts, Hornets, Shamon, Warhead, Proglass Will run and handle better with a longer and wider Cavitation Plate Not taking away from it.
See ya Jimmy
Jimmy I agree, no wonder Joe Monohan made an bigger cavitation plate to add to a k&b lower.
 
Yep I have quite a few of them. What gets me is that some put a lot of negative in and take weight out of the nose. The hull could go slower. Try 0 Deg in the lower and add a cavition plate Extention and weight to the nose and gain more speed and handling. I Think that i race the heaviest hulls around and win plenty of races. The ones that i lose is due to my driving not the hull. Also running the wrong lower will cause problems also. The Hornet, leecraft, proglass need the K&B Lower. The shamon, Warhead need the lawless, Not sure about the HTB as I have never ran one. The position of the prop behind the hull is very very important as well as were the hinge pivots.

See Ya Jimmy
 
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