The extensions are one meter long (39.4”) built from a female mold using ½ inch thick 5.5 pound density CoreCell foam using polyester resin, 24 oz. tri-axial cloth and color match gel-coat on both sides. The rear boarding platform is 5 ft long with a raised non-skid surface. The part is designed to overlap the rear edge flange creating a smooth junction on the outer surface of the hull.

The boat was built, laying up the hulls first, then transom with the steps was glued into place. A flange on the transom was joined with the outer skin of the hull. The two surfaces glued together created a flange all way around the transom of the boat. This flange was trimmed creating an arc and an aluminum molding was installed. A problem I have encountered is that the transom is not installed uniformly from boat to boat and even from one side to another. This means that the flange is not the same thickness, and the leading edge of the flange is not uniform. The process I worked out solves these problems and makes the installation much easier.

Take the plywood cradle that the parts are stacked on and screw four 2x4 legs on it at the right height so the part lines up with the boat’s transom. This stand saves lots of time when lining and trimming the part with the boats transom.

Take the aluminum cap-molding off both of the transoms and grind off caulking. The stainless hand rails do not need to be removed, but I would tape them to save time at clean up. Taping the rear steps and sides again would be a time saver.

Fit the new part on to the transom, using two 1” drywall screws and fasten the part onto the boat at the two top corners. ( Picture #2)

Mark the high spots between the part and the outer edge of the hull’s flange. Grind the high spots away and re-fit. Repeat until there is less than an 1/8” gap on the outside junction all around. I use a “Rotozip” tool with ¼ inch carbide bit to clean out the inside bottom edge of the hulls transom.

Due to the clamping and gluing process when the transom was glued into the hull, the flange on the boat is not uniform in thickness. If the flange is too thick forcing the part inwards creating a step, use the Rotozip tool to trim away the fat part of the flange. If the part is creating a step out, the Zip tool can be used to trim the inside of the flange of the part or using set screws shown on the drawing to line up the two outer surfaces. Fasten part on the hull with dry-wall screws 10” to 12”apart. To make the fairing job easier, it is absolutely essential that the side of the hull is in line with the part without a step. When the part is in perfect alignment, put alignment lines between the part and the hull. (Drawing #1)

Fit the floor board in and trim until it is seated and level from side to side. (you can put a cardboard box on the floor board and lay a straight board on top of it, and it should be in line with the rear cross beam) The back end of the floor board has to be cut around a 45 degree angle and must mate the transom’s raised flat surface. The front end should butt against the back side of the first step raised 2” from the original floor. This creates the proper deck angle for good drainage.I

When the floor board is properly fitted, mark the upper surface of the floor board against the side of the extension with a pencil. Take the floor board out allowing for the thickness of the floor board mark a reference line. Prep the surface and glue in foam angle support strips. Check that the floor board rests on the foam support strips. Prep the surface and glue in the floor board only to the extension. Use enough adhesive so there is no gap or voids between the two pieces, clean off excess adhesive. The floor board is glued into the part while it is still on the boat so it locks in the alignment of the part to the hull.

While the floor board is setting up repeat the process on the other hull.

Lift off the extension with the floor board glued in. In the inside, using a drum tool clean up the junction between the floor board and the extension. Using the 3” bi-x cloth, glass the inside junctions and the back end of the floor board where it meets the transom.

Prep all the areas where the extension and floor board is going to be joined with the hull. You need to use secondary bonding adhesive that gives you at least a half hour to 45 min. working time. Apply the adhesive to both surfaces and fit the extension into position. Make sure that your reference lines line up and fasten the part in position. Clean up all excess adhesive. Let it set up over night.

An experienced fiberglass person with a helper should be able to glue the extensions on both hulls up to this point in one working day.

Take out all the fastening screws, grind the junction down to the fiberglass 2” back from both side of the junction line. Using the finishing fiberglass tape, glass the outside junction all around. Once the junction is set up, sand and level the surface. Mix a batch of pre-catalyzed color match gel-coat with cabosil, and mix it well until it is very smooth in texture. Level and fair the junction. When the junction is perfectly fair, gel-coat the junction, wet sand and buff. (Picture #3)

In the inside of the extension, use a drum tool and clean up the junction between the floor board, part and the hull. If the gap is bigger ¼ inch between the part and the hull, lay in a thin layer of finishing glass cloth. The rear junction between the floor board and the transom, grind both sides back 2” and round the corner. Lay in one strip of 3”bi-x and cover it with 4” finishing cloth. (Picture #4)

Mix batch of good quality Iso resin, gel-coat, with cut glass and cabosil. With this catalyzed putty using the round end of the tongue depressor stick, create a neat radius junction at all the bonded areas. Once cured, use a gel-coat cabosil mixture and make all junctions smooth. Sand surface and spray finishing gel-coat layer. Wet sand and buff junction.

Extend the waterline on to the extension. De-wax, sand underwater surface and coat with a bottom barrier coat. Paint the bottom with antifouling bottom paint.

Note: When glassing and puttying the junctions, the neater and cleaner the job is done the less time is needed to sand and clean up the mess.