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Jack Plate Plans Construction Notes
Adding a trim bracket

(Purchase Plans, if you haven't already.)

An optional feature for your jackplate is a bracket for the hydraulic cylinder used in a racing-type trim system.

In this type of system, a single hydraulic cylinder is located along the centerline of the boat. One end of the cylinder is bolted to the motor's tilt assembly. The other end is attached to the boat in one of several ways. A common arrangement has the cylinder passing through a cut-out in the transom to a bracket bolted to the inside face of the transom.

The first systems I assembled used a bracket on the outside face of the transom. However, this setup presented some difficulties when raising or lowering the motor via the jackplate: anything other than a minor vertical adjustment required relocating the bracket on the transom.

My solution to this problem was to put the bracket on the jackplate itself. Now, when making a vertical adjustment, both ends of the cylinder move up or down together and the motor-cylinder-transom geometry remains constant.

The exact demensions of the bracket, and its precise location on the jackplate, will depend on the cylinder used. My system uses a Mercury outboard cylinder which is about ten inches long in the closed position.

Although the bracket is not attached to the transom, it still "leans" against it. To avoid putting too much strain directly onto the jackplate, the bracket extends forward to within a quarter inch of the transom. That 1/4" gap is filled with pieces of aluminum fastened to the transom, which give the bracket something solid to land on and in turn protect the transom from the edges of the bracket.

I use six-inch lengths of 4.5" x 4.5" aluminum angle for this bracket. I cut a 1.5" strip off one leg of each piece to make 3" x 4.5" angle. The 1.5" cut-offs are screwed to the transom for the bracket to lean on.

Again, the exact size of your bracket, the distance between the two halves, and the size and position of the bolt attaching it to the cylinder will depend on the hydraulic cylinder you are using.

(Purchase Plans, if you haven't already.)

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