Jack Plate Material

K

kmercury

Cadet
Joined
Aug 31, 2010
Messages
29
Hello,

I recently bought an old Starcraft with a 15" transom. It has a Johnson 40hp long shaft on it so I get a lot of back splash at WOT.

I would like to build a jack plate out of aluminum angle and plywood. I was thinking of 3x3 1/4 inch thick on the angle and 1.5 inch think lay-up of 3/4 ply...

thoughts? do you think this will be sufficient for a 40hp? Small drawing attached

ThanksJACKPLATE.jpg
 
W

Wayne Burgess

Cadet
Joined
Nov 3, 2008
Messages
27
Re: Jack Plate Material

Recently built a jack plate using 1/4'x3"x 12" aluminum angle to raise a modified long shaft 9.9 on a 15" transom. Worked well for me.
 
C

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,149
Re: Jack Plate Material

The thickness of the angle iron is very important. The Jackplate on my speedboat (135HPV6 motor) is about 3/8" think aluminum. I do not know if 1/4" is sufficient for your application, but it may be.
 
5150abf

5150abf

Vice Admiral
Joined
Aug 12, 2007
Messages
5,808
Re: Jack Plate Material

Depending on the design 1/4'' is fine, our motor pans at work (Bennington) are made from 3/16'' and are rated for 150, our elliptical center tubes have a 1/4'' backboard and some of those are rated for the Yamaha 350 outboard so it should be fine again depending on your design.

When I was at Suncruiser years ago the motor pans had 3/16'' U channel and double marine ply for the backboards very similar to what you are wanting to do.
 
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