Windshield Bedding

Rebedded Center Windshield, 5/4/2008

Well, this is a project I had put off for some time because the planning and preparation seemed daunting. Our center windshield has leaked, sometimes badly, since we bought the boat. In the picture on the right, the damage to the lower-right corner of the wood window frame is evident, and there was comparable damage to the other side. I sorted out most of the planning over the winter, so Michele and I decided it was time to tackle the project.

Learning how the glass seals in the frame to prevent water intrusion was the first challenge. Applying caulk around the glass might seem like an obvious fix, but it doesn't hold up. It also makes later repairs more difficult, as we soon found out. The Cape Dory 28 chat board proved very helpful: other owners had already done the job, and provided lots of guidance. The glass sits against a bedding material to seal against water intrusion. An exterior gasket then holds the glass tightly in place against the bedding. In our case, the bedding had dried, cracked, and shrunk over time, so it was no longer providing a seal. In addition, the exterior gasket was brittle and loose.

Finding the right material was the next challenge. Recent reports were that Florida Marine Tanks carried all of it, but they insisted otherwise when I called them. Ultimately, I found the bedding material at Napa Auto parts: 3M "Windo Weld" ribbon sealer. I used the 1/8" by 1/4" size. Other Cape Dory owners used a slightly larger size, but this seemed to match our old sealer almost exactly. I found the exterior gasket, again with the help of another owner on the CapeDory 28 board, at American Marine Products: "TP-139" was right on. It comes in black or white -- we used white, which matched the old gasket.

The picture below shows what we found after removing the exterior gasket and working the glass free from the bedding and frame. Most of the black bedding material was so dry it fell right out. A little remains in the upper right side of the picture. In addition, there was plenty of caulk (also visible), presumably from a prior repair attempt. The caulk filled the frame almost all the way around. It was a real bear to scrape out of the groove where the exterior gasket lip inserts in the frame, and it had to come out or the gasket wouldn't fit right. Without all that caulk, we'd have been done probably in 30 minutes per pane.

Below, the glass is back in the frame. You can see the black, spongy bedding along the top and bottom perimeters. It is extremely sticky, so it was difficult to set the bedding into the frame in a straight line. No matter -- it will be hidden. Once the bedding was in the frame, we gently set the glass into place, and firmly pressed the edges against the bedding. The outer gasket is already in place on the left.

The lower pane is finished. You can see the old exterior gasket in the edge of the upper frame.

We did the upper pane next, so it is complete now as well. The port and starboard panes will be done soon.