Mounting the Bilge Pump Frames

After the bilge pump frames were mounted in their ideal location and the bolt holes for the bilge pump were drilled, it became time to more formally mount the bilge pump frames to the bulkheads.

Those little brass screws are only there to hold the frames in place. The fiberglass and resin are going to do the actual mounting. Bonding the frames to the bulkhead over paint would result in a bond only as strong as the paint adhesion to the wood. This means that the paint needs to be removed and the surface taken down to the bare wood.

Using a block plane, I scraped the paint off the wood and freshened up the woods surface. There are many holes in this area from the multiple attempts to position the frames, so the correct holes were circled and the outline of the brackets marked. This will aid in positioning the frames into the correct holes when I go to mount the unit with the fiberglass.

With one screw into the brass L bracket, I was able to add a large clump of chop strand mat onto the end of the wooden frame. Swinging the frame into position pressed and pinched the chop strand mat between the bulkhead and the frame end. The other brass screws were added to help hold it in position, but none of the screws were tightened yet.

With the aft end of the frame loosely attached, I was able to swing the forward end of the frame away from the angled bulkhead. This created enough space for me to stuff in some more chop strand mat before pinching the frame against the bulkhead. 

With both frames pinching chop strand mat against the bulkhead, I was then able to tighten all the brass screws to lock the whole unit in place and in position.

The chop strand mat was all added dry, with no resin at all. Doing all the work dry, I am able to work in a clean environment without getting resin all over my tools (or the rest of the boat). I will need to pay extra attention to make sure that the resin makes it all the way to the center of the chop strand mat to avoid incomplete wetting of the mat. 

This can be easily achieved by thinning the epoxy resin before application, making it runnier and more able to penetrate deep into the wood and surfaces. It is important to fully saturate the whole structure before applying the fillets which will be a much thicker epoxy mixture and won't allow much penetration into the dry contact of the frame and bulkhead. Applying all the epoxy at once allows the entire unit to cure as a single giant polymer which will have much greater strength in the end.