How to Build a Fiberglass Outboard Bracket for PocketShip
By John C. Harris - 2010
Here are instructions for building a light, strong, elegant outboard bracket for PocketShip. Since we have a lot of scrap six-ounce fiberglass laying around that's what we used, along with Peel Ply.
Here's the drawing for the finished outboard bracket.
A very simple "female" mold is built from cheap plywood and scraps.
The mold is coated with generic paste wax. It's hard to have too much wax on the mold.
A wooden spacer will be laminated into the motor mount to give the outboard's clamps a good grip.
The first thing into the mold is a layer of peel ply, for a smooth external appearance and a better chance of releasing cleanly from the mold.
More wax is brushed onto the peel ply, and all wrinkles are eliminated.
You'll need one of these fiberglass rollers to saturate the layers of fiberglass cloth.
I used 50 layers of six-ounce fabric (!) wetted-out in two 25-layer units. This was overkill. For a 2- or 3hp outboard, a total of maybe 28 layers of six-ounce fabric would have been sufficient, in two 14-layer units.
The fabric is wetted out in a simple wooden tray I built for the purpose, to keep the excess resin from going all over the place. 100% of the air must be rolled out. This takes a lot of work, and you have to work very fast, as you'll need nearly a gallon of epoxy. And it wants to set up in a hurry!
Here are 25 layers of fiberglass completely wetted out, ready to put in the mold.
Fiberglass is set into the mold, pressed and rolled tightly to eliminate air bubbles. Then the block of wood is set in place.
You'll need a big, strong fillet between wood and fiberglass. (The fiberglass is still uncured. Again, you're moving very quickly here.)
The second and last 25-layer mat is pressed into the mold, sandwiching the wooden block.
When it cures, trim the overhanging material off with a 4-inch cutoff wheel. It's the same wheel used by welders and metalworkers.
Lift the bracket out of the mold, and peel off the peel-ply. Peel Ply is available by the yard.
The bracket will need some heavy-duty sanding. If you have air bubbles, you'll need to fill those.
The exposed edge of the wooden filler block must be thoroughly coated with epoxy.
Finish the bracket with several coats of paint, and through-bolt it to the stern of your boat.
The finished bracket is light, clean, strong, and unobtrusive!