Cavitation Plates

[mikedoz1]

Hello everyone! I am writing in about cavitation plates. What do they do? does it make a difference? are they worth buying? I have a 2000 MacX with a Suzuki 50HP on it. Thanks, Mike

[DaveB]

Personally, I wouldn't put them on my MacX. They are for higher end speeds for out of the hole.
There are no problems if you keep your motor cavitation plate 1 inch lower than the hull.
Dave

Hello everyone! I am writing in about cavitation plates. What do they do? does it make a difference? are they worth buying? I have a 2000 MacX with a Suzuki 50HP on it. Thanks, Mike

[Nautek]

The advantage of the foil is to get up up on the plane quicker and keep you on the plane at lower revs
They also prevent heel on high speed turns
They do work
I don't know how they would work on a boat the size of the Mac but it would be good to hear from anyone that has one fitted

Allan

[Seapup]

My 90 came with a dolefin hydrafoil on the cavitation plate. I took it off after a few months. I may try it again this summer for some speed testing to see if it makes any difference, but was turned off by a few negatives. My motor is heavy and setback on a jackplate and wedges, so probably resulted in more extreme results than a basic 50 would see.

Negatives: At speed if someone moved on board and the boat leaned to one side a tad it would want to take off in that direction. Steering was a handful at high speed. The motor had to be tilted the whole way out when sailing, tilted partway it acted like a brake. If the motor was not pointed straight back the rudders would hit it raising and lowering them.

It did make a huge difference when trimming. The motor felt like it was locked in the water and the bow went straight up and down as you trimmed. Not sure if this is really an advantage or useful. The only advantage I found was in sharp waves you could really trim the bow up to keep waves from breaking over it as easily. You could also keep it trimmed bow down so much that the boat would plow straight ahead and be very squirrelly.

[Hamin' X]

Please take note: The factory states in the owner manuals to not use the devices:

Do not install a lifting hydrofoil on the cavitation plate of the
outboard motor. These are airfoil shaped wings, offered in
various sizes and shapes. Their purpose is to provide lift at
the stem of the boat. This raises the stern and forces the bow
down, allowing the boat to get up on a plane more quickly. If
they do keep the boat level when coming up on a plane, the
ballast tank may not drain completely when the boat is
underway. You may think you have an empty tank, but you
may not.
These hydrofoils create another problem when the boat turns
or leans sideways while underway. The lift that they provide
goes straight up the centerline of the outboard motor, adding a
strong force to promote further leaning or capsize.
These devices can exert a large amount of force; enough to
snap off the cavitation plate that is cast as part of the drive
shaft housing. Avoid them.

Probably good advice... My 2001 X with a 50 HP Suzuki has some holes in the motor cavitation plate where the PO had them mounted. The were stowed under the aft berth and I have not seen the need to remount them.

~Rich

[mikedoz1]

Thanks again everybody for the great replies. It sounds like its something I don't need, so you have just saved me some money! Happy sailing!!