Building a hard-top dodger

Here’s how to get that professional finish

Issue 33 : Nov/Dec 2003

My Sunbrella dodger is a wonderful asset, and I can’t imagine why I sailed so many years without one. I keep mine in place nine months of the year and, after 12 years of use, it was showing signs of age. A new fabric dodger would run in the realm of about $700, but at the Annapolis Sailboat Show I saw an alternative that I found intriguing. It’s a fiberglass hard-top that fits on the existing stainless-steel dodger frame and has removable Sunbrella side panels. This semi-permanent hard-top also allows you to mount equipment on its underside, such as a GPS chart plotter, light, and horn.

I decided this was the way to go. I’ve done fiber- glass projects in the past — such as glassing in bulkheads, fuel tanks, and an engine bed when I built my boat from a bare hull — but nothing as large as the 4-foot by 8-foot fiberglass panel that would be my new hard-top dodger. Certainly nothing that required the final product to have a mirror-like gelcoat finish.

Our boatbuilder friend, Chris Bauer, visits us regularly when displaying his Bauer dinghies at the New York and New Jersey boat shows, so one evening over a bottle of Merlot I asked him to suggest the proper procedure to be followed in creating my hard-top dodger. With his tutelage, I was able to lay up an almost professional hard-top, which is now in place on my schooner, Delphinus.

Building the mold

The project began with creating the mold — the form on which the fiberglass was to be laid up. Although building this mold is a big project, it’s a necessity in creating a professional-looking final product. I began by screwing wood stringers to the bottom of a 4-foot by 8-foot piece of 3⁄4-inch plywood. The stringers prevent it from twisting. Then I placed the dodger frame, upside down, on top of the plywood (see photo 1). Four-foot pieces of wood (the width of the plywood), with an angled cut that matched the curve of the stainless steel frame, were glued and screwed to the plywood base (see photos 1 and 2). These provided the base to which a Formica sheet would be glued. The Formica gives a smooth and fair curve for the fiberglass layup.

In laying out this curve, wood blocks of the proposed thickness of the final hard-top are placed between the stainless-steel frame and the wood mold so the proper curve can be maintained on the inside of the final hard-top. The wood base was completed once the wood cross-pieces were all in place, every few inches down the length of the plywood.

I drew the outline of the perimeter of the proposed dodger on a 4-foot by 8-foot sheet of Formica, then I contact-cemented the Formica in place on the wood frame. Small wood blocks were glued on the outside edge of the hard-top perimeter-line. These blocks provided the backing for a strip of vertical Formica (about 2 inches high) that created the outside edge of the hard-top.

Since a fiberglass layup doesn’t like sharp corners, a cove had to be established between the Formica base and the vertical Formica edge-strip. Although this cove can be created in several ways, on advice from Chris I decided on the technique used by professional moldmakers — that is, creating a cove using a wax “fillet” made just for that purpose (see photo 3). These inexpensive rolls of wax fillet are available from companies that supply commercial moldmakers and boatbuilders. They come in several radius curves. The fillet was unrolled from its spool (since it was wintertime and my garage was cool, I used a hair dryer to make the wax more supple) and pressed into the right angle of the two pieces of Formica. Then a heated radius tool melted the wax into a smooth corner cove molding (see photo 3), bonding it to the Formica. Instead of the commercially available radius tool, a heated steel ball, of appropriate diameter, can also be used for this fairing job.

Laying up the fiberglass

Once the mold was finished, the fiberglassing work could begin. Chris suggested the following layup procedure, and I bought the materials I needed, based on his schedule:

1. Coat the mold with two coats of mold-release liquid. Let dry between coats.
2. Pigment the gelcoat and apply to the mold. If you plan to finish the hard-top with a two-part linear polyurethane paint (such as Awlgrip), then tinting the gelcoat is unnecessary. If a gelcoat spray-gun and high-pressure, high-volume air compressor are not available, the gelcoat can be rolled onto the mold.
3. Allow the gelcoat to cure about 10 to 12 hours.
4. Lay in a layer of chopped fiberglass mat and saturate with polyester resin. Roll out any air bubbles with a ribbed air-bubble roller, working from the center out toward the edges.
5. Lay in a layer of woven roving and saturate with polyester resin. Roll out the air bubbles in the same way.
6. Let cure for about 6 to 8 hours.
7. Coat the balsa core and previous layup with polyester resin and lay the balsa in place.
8. Taper the edges of the balsa with a paste made of polyester resin and glass micro-balloons. If there is a pronounced curve to the hard-top, Cabosil, a fumed silica powder, can be added to the mix to prevent sagging.
9. Saturate the balsa core with polyester resin.
10. Let cure for 6 to 8 hours.
11. Lay in a layer of chopped mat and saturate with polyester resin. Roll out air bubbles.
12. Lay in a layer of woven roving and saturate with polyester resin. Roll out air bubbles. Make sure this last layer has as smooth a surface as possible.
13. Wait at least two days before removing the hard-top from the mold.

Advance work

In preparation for this layup, the four layers of fiberglass can be cut to approximate size well before starting. The balsa core should also be cut to size before starting. Note the circular cutouts along the outside edge of the balsa panel (see photo 4). These are so the bolts that will mount the hard-top to the stainless-steel frame will pass through solid fiberglass rather than through the balsa core.

Although I’ve seen hard-tops made without the balsa core, this feature has several advantages. It not only provides great stiffening to the hardtop, but it also means that when electronics are mounted to the underside, they don’t have to be through-bolted.

Before starting the fiberglass work, two coats of a mold-release barrier must be put on the mold to prevent the fiberglass from sticking to the Formica (see photo 5). I used a commercially available water-soluble mold release containing ethyl alcohol and ethanol homopolymer. This mold-release liquid is of water consistency and can be sprayed on with any ordinary sprayer. Since it is water-soluble, it has the advantage of being easily removed from the finished fiberglass hard-top with just water. Easy removal of the mold release is especially important if repairs are to be made in the layup after removal from the mold or if you plan to finish the hard-top in a two-part polyurethane paint.

After the fiberglass layup has been completed according to the lay-up schedule, the hard-top is removed from the mold. Then the edges are trimmed and any repairs that are necessary can be made to air-bubble voids and so on (see photo 6). If the hard-top is to be painted, now is the time.

The layup described produces a hard-top with a glossy top and an underside that shows the pattern of the final woven roving. If this underside pattern is undesirable, it can be masked with a resurfacing coat, such as a paste of epoxy and filler.

Installing the hard-top

Finally it’s time for the fun part: mounting the hard-top on the dodger frame. Most dodger frames made for a fabric dodger are held upright by the fabric, but I needed this frame to be self-supporting and also a bit stronger, so I added additional stainless steel supports fore and aft and port and starboard (see photo 7). Although our hard-top weighed only 48 pounds, having help to put it in place was a good idea, because its size made it awkward to handle.

With the hard-top on the stainless-steel frame and bolted in place, it was time for the fabric panels (see photo 8). Since I have a Sailrite sailmaker’s sewing machine, I cut the top off the old fabric dodger, leaving just the sides. Although this fabric was old, it still had a couple of years of life before new side panels would have to be made. If you don’t have a sailmaker’s sewing machine, you might be able to do this job on a beefy home sewing machine (see “Sewing’s Not for Sissies,” Good Old Boat, January 2003). Or a local sail or canvasmaker can do the work for you.

The fabric sides are connected to the hard-top by sewing a preformed, Dacron “bolt-rope” to the top edge. This bolt-rope then slides into a matching bolt-rope channel that is screwed to the underside of the fiberglass hard-top. These channels come in either a semi-rigid anodized aluminum extrusion or in flexible vinyl and create a secure and spray-proof joint. These channels and bolt-ropes are available from Sailrite.

With the new dodger completed, I now had a permanent and firm location for a horn, GPS chart plotter, and dome light. The wiring for these devices is brought up through the cabintop using watertight deck fittings, and the wires are secured to the stainless-steel frame with nylon wire-ties.

I also fastened an aluminum boltrope channel under the aft edge of the hard-top. This gives me a firm spot to slide in a cockpit canopy (see photo 9) or a cockpit winter cover (see photo 10).

I think the idea of having fabric sides on my hard-top is the best of both worlds, since it allows me to roll up the front of the dodger for unfettered air flow during the dog days of summer. I am, however, toying with the idea of building fiberglass side panels (port and starboard) for my hard-top dodger — but that’s another story.

Thank you to Sailrite Enterprises, Inc., for providing free access to back issues of Good Old Boat through intellectual property rights. Sailrite.com