Effects of a long shaft OB VS short shaft.

[Procastinator]

Does a long shaft on an outboard effect the prop that should be used? I understand how pitch and size of prop work and to monitor tach to make sure prop is functioning in range. My 16 ft. conquest has a '86 50 HP Eventide long shaft and I need to get an idea of were to start with a replacement prop.

Second question: how do I tell what the pitch is on my current prop?

Ultimately I am looking for some speed and to have current prop as a spare. My OB is very quick to plane and can be adjusted when more boaters are traveling with me.

Last note: I need to install tach. Will ask the google and the motor guys.

Thank you
Mike

 

[fhhuber]

Mainly its an issue of getting the prop to the right depth under the water.

Long shaft when you should be using short and the engine will be trying to drive the nose of the boat up. You have to adjust engine trim to bring the nose down. And now you have the prop so deep that you have negated the shallow draft design of the boat.

Short shaft when you should use long shaft can have the prop and the water intake for the engine cooling system out of the water which is just bad all the way around with the prop mostly whipping air into the water and the engine burning up from lack of cooling.

So you want the correct shaft length for your transom.

 

[Procastinator]

thanks