motor shaft height question

T

todd c

Active member
looking to buy a new motor and not sure whats better. my boat drafts in 5 or 6" of water and has a jack plate on it that lifts the motor 5 or 6" up. a short shaft 15" with jack plate all the way up prop will be even with bottom of boat wich will be great for low tide. i will not have to pull the motor up by hand to tilt up i can just use the elec. jack plate. or do i want the long shaft to dig deeper in high tide/ocean? then have to lift and tilt by hand so i dont hit rocks in the shallow. thanks.
 
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BTW: Short shaft is 15", 20" is a long shaft.
Is this a tiller steer or remote steer boat?
When you are running on plane, you want the cavitation plate about even with the bottom of the boat. So that should determine what shaft length motor you get. Having a jack plate is fine, but the motor still needs to be in the right position when on plane.
To low and you loose performance from too much drag. Too high and you'll cavitate & prop will lose grip (which equals over rev'ing: bad).
Also, you need to make sure that you keep your water intakes submerged when you are idling around with the motor raised.
As log as your boat can handle the extra weight of a jack plate, go for it.
 
My man todd,,,,
Already looking to get new engine? That set up is a gem the way it is. Hunting 2 guys that tohotsu will take you to your grey hair days.( I know you dye) forget that.... If need be, stick with the 20 inch long shaft. 15 inch will suck on that boat turning will be a nightmare. That is why I got that jackplate to work shallows....Carl is correct cavitation plate should be even with bottom of boat, that should be your starting point, then adjust jack plate according to situation....I guess your thinking horsepower to cross the sound to LI , your always welcome. Take the ferry instead and hunt the 17, you have a spot.

Mister Coles
 
The set up on it now is long shaft, and with the jack plate all the way up cavitation plate is even with bottom of boat. with jack plate all the way down cavitation plate 6 inches lower than bottom of boat and prop/fin much lower. what i really want is j.plate all the way down and cavitation plate even to get on plane correct? is that the way it should be set up? thanks
 
Yep, when down, the cavitation plate should be even or slightly below. Sounds like they mounted the jack plate too high on the transom.
 
You want the C plate even or just a scooch (technical term) below the bottom of the boat, THEN you can jack it up, a few inches, for low water at slow speed because the water intake will still be below the water.
 
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