Blue View - Replacing & Rebedding a Portlight


We have replaced almost all the portlights on Nine of Cups over the years. The only ones we hadn't gotten to were the three on the transom. They were crazed to the point that they were almost translucent, and replacing them had been on the to-do list for quite a while. We were recently varnishing the trim in the aft cabin, and noticed that two of the three transom portlights had also begun leaking – nothing serious - but at least a small drip. Now seemed as good a time as any to replace them.

The process wasn't all that difficult. Below, I have listed the tools and supplies I used. It took about 3-4 hours per portlight. It may require more or less time depending on how long it takes to remove the old caulk. You can watch a video that shows how I went about the job at this link.


  • Isopropyl Alcohol

  • Small container for decanting the alcohol

  • Ink marker

  • ¼ sheet 220 grit sandpaper

  • Dow Corning 795 silicone adhesive and sealer - ~3/4 tube per portlight

  • 24-36 2”x2” squares of paper towels – cut from standard sheets of paper towels

  • Masking tape – any kind will do as it will only be in place a few minutes

  • Disposable gloves

  • Polycarbonate, clear. We use ¼ (6mm) on Nine of Cups


  • Variable speed jig saw with fine toothed blade, suitable for cutting plastics. If you don't have a jigsaw, you could also use a coping saw or even a small hacksaw.

  • Screwdriver (hand or battery)

  • Caulking gun

  • Razor or box cutter

  • Metal putty knife

  • Scissors

  • Straightedge

  • Small trash can with plastic liner