My Columbia 26 project boat, like many others of the same age, came with a box style bow hatch. Typically, this style of hatch has a wood, usually teak, frame and either a plywood or Plexiglas top. These hatches are hinged and seat in a recess around a raised hatch opening. Keeping water out depends on a seal trapped between the bottom edge of the hatch and the recess surfaces.
Problems arise as the seals deteriorate, the wood frame rots and the top surface either becomes scratched, broken or delaminated. In fact, the one on my boat was so bad it was thrown away before I acquired the boat.
I reviewed my options as I worked on other parts of the restoration. I could simply replicate the original design but it would have all the original problems; leaky seals and the need to refinish the wood on a regular basis being the prime ones. I was looking for a better solution.
For my final solution, I decided to fill in the recesses around the hatch coaming and then laminate a flat fiberglass surface over the opening. The new surface would form a flange to fit the hatch while keeping the strength of the coaming intact.
My next problem was to actually find a hatch that fitted. I started by measuring the existing hatch coaming and making an accurate scale drawing of the side profile and overhead view of the hatch area. I then began looking through the catalogs of all the hatch suppliers I could find, both in print and on the web. I quickly found that most new hatches are square while my older hatch opening was rectangular.
I began looking at hatches on eBay. I set up an automated search that emailed me any time a new hatch appeared on eBay. Many of these hatches were NOS (New Old Stock) and many were also rectangular. I was eventually able to buy the perfect size hatch at a very reasonable price.
Once I knew I had a hatch in hand, I proceeded with the actual installation work. I filled the recess around the coaming with pieces of mahogany. I first roughed up the surfaces of the recess with 80-grit sandpaper to provide a good bonding surface. The filler pieces needed a little work rounding the edges so they would fit snuggly in the recesses. Once they fit well and were trimmed for length, I epoxied them in place with W.E.S.T. epoxy and high density filler.
Once the epoxy had cured, I sanded the surfaces smooth and radiused the corners of the filler strips. This radius is critical in allowing the fiberglass to drape over the edge of the coaming without forming a bubble. I also filled in any remaining voids around the filler strips with epoxy filler. The fiberglass would extend over the open center of the hatch area. To provide a firm base to support the laminations in this area, I made a center filler piece out of thick artist’s foam board. I tapered the sides of the filler piece slightly so I could wedge it tightly in place. It fit so well that I didn’t need any additional support to keep it from falling down through the opening. I covered the board with thin plastic sheeting before I wedged it in place, to keep the epoxy from bonding to it.
I used alternating layers of 24 oz. Double Bias Stitchmat and 9 oz. fiberglass cloth for the lamination. I minimized any overlaps of the stitchmat as it would soon build up high spots in the overlapped area. I ran the laminations down the side of the coaming and across part of the deck surrounding the coaming. I varied the amount of overlap on the deck to form a feathered or tapered edge, making blending it into the deck contour much easier.
I used more W.E.S.T. epoxy for the laminations as epoxy will give a stronger mechanical or secondary bond than polyester resin. I applied five alternating layers of cloth and stitchmat. The resulting lamination was about 3/8” thick solid fiberglass. It was probably overkill, but I wanted the flange to be as strong as the rest of the deck. I didn’t want a breaking wave to push the new hatch through the opening.
As careful as I was to keep the top surface of the lamination smooth, I did develop high and low spots. Instead of sanding away laminations and possibly reducing the strength of the flange, I applied a thick layer of epoxy filler round the edges of the top surface and then pushed an old shelf, covered in a plastic painter’s tarp, into the uncured filler. When the filler cured, it provided me with a smooth starting place for my final finishing.
I did most of the final sanding with a long board covered with 80-grit sandpaper. A long board is simply a long piece of wood with two handles on the top and sandpaper on the bottom. A long board spans many smaller imperfections and allowed me to work the surface down to a straight and level final finish.
The next step was to cut out the center opening. After marking the location of the cut-out, I drilled an access hole for my jigsaw blade and proceeded to slowly cut the opening out. Fiberglass is rough on saw blades, so I used a slow cutting speed and changed blades once during the cut. I used medium toothed metal cutting blades in my Bosch jigsaw. I had to sand a few areas on the edges of the opening to get the hatch to fit.
Before final installation, I painted the deck and new hatch coaming, using two coats of Interlux epoxy primer followed by two coats in Interlux Perfection two-part polyurethane paint.
I began the hatch installation by drilling the holes for the hatch fasteners. I was lucky in that the fasteners penetrated solid fiberglass, so I didn’t have to worry about sealing a wood core. Since I could get to the bottom of the hatch fasteners I elected to use machine screws and Nylock nuts to hold the hatch in place.
After drilling the mounting holes I removed the hatch and applied blue masking tape all around the opening and on any surface I didn’t want smeared with sealant. Liberal application of blue tape speeds clean up and reduces sealant mess. I placed the hatch back in the opening and traced around it. After removing the hatch again, I cut away the tape under where the hatch flange would sit.
I also applied blue tape to the mounting flange of the hatch after placing the fasteners in the holes. I also placed a rubber washer on each fastener on the underside of the hatch flange. The rubber washers keep me from over tightening the hatch and squeezing out all the sealant. A thin sealant layer is much more likely to shear and provide a path for leaks.
My sealant of choice for above the waterline application, like this hatch, is 3M101 polysulfide sealant. It is a good adhesive sealant yet not aggressive enough to make removing the hatch for rebedding difficult. I applied a generous bead of sealant on the coaming and the hatch flange, put the hatch in place and tightened the fasteners. I cleaned up the excess sealant that squeezed out and then removed the tape while the sealant is still soft. I find it much easier than trying to remove tape covered with cured sealant.
This hatch replacement process is one of a variety of options available to anyone restoring n older boat. I found it an easy process that could be broken down into a series of easily accomplished tasks and a reasonable cost. The end result provided all the benefits of a modern hatch in my project boat.
DIY-Bow-Hatch01: This view of the bow hatch coaming shows the mahogany filler strips bonded in the recesses, rounded over, faired with epoxy filler and sanded smooth. The white tube is part of the cover support used to keep the boat covered and dry between working sessions.
DIY-BowHatch02: The artist’s foam board has been cut to size, covered with plastic and wedged in place, ready for the fiberglass work to begin.
DIY-BowHatch03: The first layer of Stitchmat has been applied and wetted out with epoxy resin. This layer did not cover the sides of the coaming. This layer was left to harden to provide further support for subsequent layers of fiberglass and epoxy.
DIY-BowHatch04: This photo shows the fiberglass lamination completed. The bulk of the build up is around the edges of the top surface, down the sides of the coaming and onto the cabin top. The center will be cut out and wasn’t covered with fiberglass.
DIY-BowHatch05: This close up view of one corner shows how the fiberglass laminations were carried down the sides of the coaming and onto the deck.
DIY-BowHatch06: A liberal amount of epoxy filler has been applied to the top surface of the new hatch flange. The center cut out area has not been filled as it will be cut out.
DIY-BowHatch07: A laminate faced shelf, covered in plastic, has been pushed down into the soft epoxy filler to form a smooth and level surface for final finishing.
DIY-BowHatch08: This is the handle side of the long board used for final finishing. The bottom surface of the long board is covered in self-adhesive sandpaper and then used to do the final sanding on the new hatch mounting surface.
DIY-BowHatch09: Another sheet of artist’s foam board was used to make a template for the hatch opening. After centering, it was traced around to provide the cut marks for the jig saw.
DIY-BowKatch10: With the opening cut out, the full 3/9” thickness of the hatch mounting flange is visible.
DIY-BowHatch11: After painting the cabin top, the hatch was bolted in place. Project complete.
DIY-BowHatchD01: This diagram illustrates the construction of a “Box Lid” style hatch. This example has a wooden frame with a Plexiglas top.
DIY-BowHatchD02: This scale drawing of the existing hatch opening was used to determine if a particular hatch would fit. The colored lines indicate the dimensions of a candidate hatch.
DIY-BowHatchD03: This cross section illustrated how the new hatch mounting flange was laminated over the existing hatch coaming with the support of the artist’s foam board support.