jack plate

mulli2b

Cadet
Joined
Mar 25, 2010
Messages
25
I have a old 17 foot seaark jon boat with a tunnel hull. I found a inexpensive jack plate to raise the 20in motor, in essence making it a short shaft for the tunnel hull. Does anyone have any experience with this and will it make that muck of a difference?

Bill
 

Capt'n Chris

Chief Petty Officer
Joined
May 21, 2009
Messages
461
Re: jack plate

I have a old 17 foot seaark jon boat with a tunnel hull. I found a inexpensive jack plate to raise the 20in motor, in essence making it a short shaft for the tunnel hull. Does anyone have any experience with this and will it make that muck of a difference?

Bill

It sure will look funny and it might not work, by moving your motor aft. Up is where you want it, not back!
 

mulli2b

Cadet
Joined
Mar 25, 2010
Messages
25
Re: jack plate

I'm not sure in the post where it said I was moving motor aft. I am raising motor up 5 inches.
 

DuckHunterJon

Lieutenant Junior Grade
Joined
Apr 19, 2010
Messages
1,082
Re: jack plate

It all depends on where the motor is running height wise now. I'm not familiar with your hull design, but the best thing to do is have someone drive the boat full speed while you carefully look over the transom to see where the cavitation plate is. It should be just at the top of the water when on plane. If it's sunk way down, the jack plate may help. If it is already at the surface, you don't want to raise it further.
 

joebob14

Petty Officer 2nd Class
Joined
Feb 27, 2010
Messages
170
Re: jack plate

I had the same problem with my boat. 14 ft trihull with a 15 horse honda tilller motor. sitting in the back running wide open the bow pointed at the sky and the boat would run at about 5 mph. I jacked the motor up 6 inches so that the cavitation plate was level with the bottom of the hull, I found a thread somewere on here that said thats what its suposed to be. The difference was huge. That extra 5 or 6 inches of lower unit in the water makes alot of drag moving thrugh the water. My 5 mph boat now runs at almost 30 mph. If you can pick up a jack plate to put the motor where it is suposed to be I would deffinitley do it.
 

NSBCraig

Lieutenant Commander
Joined
Aug 21, 2007
Messages
1,907
Re: jack plate

I think he meant aft cause the plate sets the motor farther back from the transom.

This usually helps more then hurts but probably does nothing to a tunnel hull.
 
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