Cavitation plate

[slimdaddy45]

Hi guys I have a 19.5' Sea Nymph SS195 I have an old 1974 Johnson 115 hp on it and sitting on a CMC tilt unit which gives you around a 6'' setback so where should I set the cavitation plate at from the bottom of the boat to be right or close for best performance has a 13.75 x 15 prop on it also have a 13x 19 spare which it wont plane with a heavy load

 

[GA_Boater]

There are no hard, fast rules. Try both higher and lower. With a setback the motor is usually set a little higher.

Make sure the motor is running like a top and the boat isn't waterloged before playing with props.

 

[slimdaddy45]

There are no hard, fast rules. Try both higher and lower. With a setback the motor is usually set a little higher.

Make sure the motor is running like a top and the boat isn't waterloged before playing with props.

As of right now I got the floor out of it to replace it found wet foam right at the back o n the drivers side the rest is dry so Ill probably leave the good dry foam havent got the other side out yet .My motor is probably 2'' high and will that cause it to wash back n forth at low speeds i have to work the wheel like a race car driver to keep it going straight its ok full throttle its just idle speed it does have a whale tail or hydra foil on it

 

[Scott Danforth]

foam should be a replace all thing

 

[Chris1956]

Most planning boats will wander at low speed. The cure is to make small steering adjustments to average a straight path. It is the nature of the thing.

The horizontal plate above the prop in an antiventilation plate. It is designed to keep air from being sucked into the prop.

The best way to set motor height is by trial and error. Run the boat on plane and see where the antiventilation plate rides. You want it at the surface or slightly above the surface. Adjust motor height as necessary.

If you have good acceleration onto plane, you may not need the whale tail. They can add drag at planning speed, which is what you are trying to avoid by raising the motor.

 

[Sea Rider]

Why is the boat using a CMC tilt/trim unit and not bolted directly on the transom ? A whale tail, doel fin will add excessive lower leg drag if doesn't ride parallel to the water level when the combo is on plane, other issue, are huge garbage collectors of anything that floats.

Happy Boating​

 

[QBhoy]

An inch above the lower hull…for a sensible starting point

 

[slimdaddy45]

foam should be a replace all thing

Why if its dry and good shape no more than I took out of wet probably wouldnt make much difference if it was left out only about a foot square piece was wet there is alot in this boat but I will replace it