Even though Pony Express, our Express 30, has had good maintenance through the years, she is beginning to show evidence of her sixteen years. One of those signs of age is cracking in the fixed ports. Apparently, after years in the sun, the Plexiglas loses its flexibility. When the boat flexes and components expand and contract, the weaker Plexiglas often ends up with vertical split. Not only is this unsightly, but also is a continual source of a leak.
With all the sealant products on the market, a major question is what to use to seal the windows. There has been a lot of discussion among boat owners on this topic. Bill Goman, former owner of Express Yachting, says it should be Versilok 406/19, a two part acrylic adhesive. There is a concern that it may create too strong of a bond and not allow for the difference in expansion of the Plexiglas and the fiberglass. Another suggestion was 3M acrylic foam tape. While several people have had success with it, 3M says it shouldn’t be used alone to hold a Plexiglas window in place. They recommend the use of screws in conjunction with the tape. There were also reports of unsuccessful attempts with silicone caulk and 5200.
Since the Plexiglas, bedded in Versilok, had worked for almost 16 years on the boat before any problem occurred, I figured it should last another 16 years, or so, if I used new material.
The Versilok 406/19, manufactured by Lord corporation, was purchased from AirDraulics / Chemical Concepts in 42 ML tubes. Each tube delivers approximately 48″ of a ΒΌ” bead and is enough to do one port. Craig Zell, of AirDraulics / Chemical Concepts (215)457-1940, also provided an insert which allowed the tubes to be used in a standard caulk gun.
The old Plexiglas was carefully removed by inserting a flat putty knife between the window and the bedding compound from the inside. Starting at the crack, since the separation had already started there, we slowly worked our way around the perimeter.
Once the Plexiglas was out, we prepared the opening for the new sealant. The biggest concern was around the edge of the old Plexiglas. The old bead had to be removed to make room for the new Plexiglas. The sealant had formed such a strong bond that chipping it could easily chip the gel coat. We found the best way to remove it was to scrape it with the end of a sharp chisel. Any sealant that appeared to be deteriorated was removed with course sand paper. The area was then wiped down with a wax removing solvent to ensure a good bond. The new ports were cut out of smoked Plexiglas on a band saw. Final shaping and smoothing was done on a belt sander.
The area around the opening and the new Plexiglas were masked. The masking was trimmed to the edges with a razor knife. Two beads of the adhesive were applied to the opening. A heavy bead around the outer edge of the opening, and a smaller bead was applied in about the middle.
The new Plexiglas was placed in the opening and pressed in to ensure full contact. More adhesive was applied as necessary in any voids. The displaced Versilok was troweled back into the joint and wiped smooth. Because of the slight curve on the forward ports, the Plexiglas was held for about 15 minutes, till the adhesive had begun to cure. The masking was removed after about twenty minutes, revealing beautiful new ports. The job, although it looked like a daunting task, went well, and the should give lasting results. We shouldn’t have to worry about these for another 16 years.
