SV Pilgrim - 1979 Morgan 382 - Homeport: Beaufort, NC

Saturday, September 12, 2015

Replacing the Leaking Quarterberth Port, the Exterior Story – Part 2

Part 1 of the Exterior Story focused on shaping the window pane (Link: Replacing the Leaking Quarterberth  Port, the Exterior Story – Part 1.)  Thanks to everyone the left suggestions and links on the last post.  Now we are on to installing the window.

Drilling over-sized holes for fasteners in the acrylic window pane.

Due to thermal expansion / contraction the pilot holes for mechanical fasteners need to be over sized.   I also drilled a slight counter sink on the exterior pilot holes to provide space for butyl tape bedding.  This work was all done on a drill press.

Clamping window in place to test fit, mark fastener locations, and scribe window opening on interior face.

The window moved from the drill press to a test fit on Pilgrim.   While the window was clamped in place we marked the fastener locations on the exterior.  On the interior we used a marker to  trace the window opening  onto the masking.

Using a marker to trace the interior window opening onto the masking.

After removing the pane, we gently ran a razor blade along the outline of the opening on the interior of the window.  This allowed us to remove the section of masking in contact with the hull while leaving the remaining window masked.  We then drilled the pilot holes the cockpit wall.

Acrylic in contact with hull exposed and pilot holes drilled.

We are using #12 stainless steel pan head screws to mount the window.  To allow for thermal expansion we included a neoprene washer between the head of the screw and the pane of acrylic.  The screws are bedded with butyl tape.  We are also using butyl tape to bed the window.

Applying butyl tape to fasteners and acrylic.

We applied three rings of ¾” wide X 1/8” thick butyl tape to the exposed acrylic on the interior face of the pane.  We have found Amazon to be a good source for butyl tape.  Here is a link to the tape we are using on this project – Dicor Butyl Tape

Fortunately the installation occurred on a hot, sunny day.  Both the acrylic and the butyl tape are easier to work with when they are warm.  In cold temps the acrylic is less flexible and more prone to cracking.  The cold butyl tape is much more firm and less likely to form into a good seal.  If completing this project in the winter, then we would have used a heat gun to warm the assembly prior to attempting the installation.

The installation went smoothly.  We over tightened the pane slightly until we observed butyl tape squeezing out around the entire perimeter.  Then we backed off the screws until the neoprene washers returned to their original shape ( approximately ¼ to ½ a turn.)

Using a plastic "knife" to remove the excess butyl tape

We use a plastic “knife” to cut away the excess butyl tape.

The completed installation.

After completing the install, overnight thunderstorms confirmed the new window is water tight.

See our Cockpit Refit Photo Album for additional images and other projects associated with the cockpit.


  1. Beautiful work, Jeff. Obviously you didn't want another opening port where you removed the old one. Have you decided not to use the quarter berth for sleeping? Ventilation not required?

    1. Thanks. Your assumption is correct. We are converting the quarterberth to storage and thus are not concerned about the loss of an opening port window. We would like to maintain some ventilation in the area and are contemplating other methods of providing some air movement through the area.

  2. Jeff,
    To polish the edges of plexiglass and most other plastic sheets, you use a propane torch or a heat gun on the edge. Run the torch lightly along the edge alternating between touching the edge with the flame and moving it away. the edge will smooth out and get clear. Do not keep the heat in one place for more than a second or so at a time. a little practice on a piece of scrap will show you how its done.