The teak spacer arrived last week along with some 30mm long bolts which NFM recommended. As it turns out the inner dimensions of the teak spacer are the exact minimum dimensions recommended for the cut out in the cabinside. Up until this point I had just widened the cut out enough to get the port through a do a quick dry fit. So, the first thing I did today was use the teak spacer as a template to make sure the cut out was the exact dimensions NFM suggests. As you can see below, there was not much more to remove from the cabinside.
Once the excess fiberglass was sanded away I dry fit the port with the new teak spacer in place. NFM suggests having a pretty significant gap around the edges of the stainless so that you can pack plenty of sealant in. They recommend sealing the port with butyl in a way that ensures that the spigot is totally covered as well as where the spigot meets the inside trim of the port. They then recommend that you pack the gap shown on the right below with more butyl to fill any space.
I am going to try a different approach. I really don’t like the idea of sealing anything on the inside of the boat, whether it be a port or backing plate. If the sealant on the outside of the boat has failed I want to know immediately and I want to be able to see where the leak is coming from. If you put sealant on the inside of the boat and the sealant on the outside of the boat fails there is a high likelihood that the water will sneak its way around and show its ugly head in some other place in the boat and you will have a heck of a time finding the leak.
To provide one example you may remember from The Last Lingering Leaks: one of the Beckson ports that came with the boat sprung a leak from degraded sealant on the outside of the boat. However there was sealant on the inside too and it literally took me 6 months to figure out that the water showing up in my starboard shelving was coming from water that had leaked in from the outside of the port! The water had gotten in between the headliner and cabinside, and snaked its way down into the locker, no where near the port. 😦
So, instead of using NFM’s butyl method I am going to try a method that is completely sealant free on the inside. In order to do this I dry fit the port and clamped it into place:
I then used Dow Corning 795 to completely fill the gap around the spigot. As readers may remember from Overhead Hatches and 1 Hatch Finished, Dow Corning 795 is an architectural grade building sealant designed to suspend glass panels on the sides of buildings and bond the glass to metal. 795 bonds well to pretty much anything and can support a lot of weight. It also remains very flexible and does not degrade in weather. I used a 45 degree nozzle hose clamped to the tube of 795 to make sure to get all the way in the gap and apply a liberal amount of sealant.
I then used M6-1 X 40mm machine screws at the top and M6-1 X 30mm screws on the bottom to tighten down the outside trim ring. I just left the outside trim ring dry fit for now because I would like to take it off next week and test the strength of the Dow Corning 795 on its own. If all is well then I will clean up the outside and seal the trim ring in place as well.
I think the port is looking pretty good so far: