That Porthole

Readers this post is about my effort to rectify a problem with the galley porthole.  It all started with our first boat builder (if you can call him a builder).  He managed to locate the port galley porthole in the wrong place.  As a consequence we ended with a hole on the partition between the galley and the back bedroom.  His solution was to make the cabin bed 5ft 6ins long.  Obviously this was going to seriously restrict the height of any would-be guests. The hole had to be relocated.  Well that’s not quite correct.  We had to have a new hole cut in the side and the disc then welded into the old hole.  In doing this a slight distortion was created in the cabin wall.  As a consequence of this the new porthole required additional weatherproof foam tape to make a water tight seal.  After doing this there was a significant amount of tape protruding from around the aluminium porthole frame.  You can see it in the following photo.
Jan here… Plus his knobbly knees

The window has been like this for two winters and one summer.  I deliberately haven’t touched it because I wanted to see if there would be any movement (expansion/contraction) in the foam tape.  You can also see in the above photo that I have already removed the pvc beading tape which covers the screw heads.  I was actually rather surprised at the amount of water retained behind the tape.  It was immediately apparent that the screw holes need to be water tight to prevent water from getting behind the porthole frame.
After carefully removing all the stainless steel wood screws the porthole was prised from the cabin wall and laid flat.  A razor knife was then used to carefully cut the excess window tape from around the external circumference of the frame.

Examining the hole revealed there was a gap between the timber porthole liner, the aluminium porthole frame and the timber framing around the hole.  I knew there was a water tight seal between the porthole frame and the cabin side so any sign of dampness in this area is due to condensation.  It forms on the cold internal side of the porthole frame and then migrates down between the aluminium frame and the timber porthole liner.  This is what’s staining the timber liner.
We can’t eliminate the condensation because it’s coming from us, the calor gas and the cooking.

You can see the gap (bottom arrow) and the face of the timber porthole liner (top arrow).  I don’t know how others have attempted to eliminate this problem but my solution was to mask the outer edge of the timber porthole liner (blue tape) and then apply a heavy bead of silicone to fill the gaps and create a waterproof membrane on the face of all the exposed timber.

Once I had plenty of silicon around the frame I used my index finger to spread it evenly, remembering not to pick my nose afterwards!  Too much silicone wasn’t a concern because any surplus would either be squeezed out internally onto the blue tape and create a seal or it would be squeezed out behind the face of the aluminium porthole frame.  Just to make sure there was a good external seal I applied another bead of silicone onto the inside of the aluminium frame before reinserting the frame into the hole.

This is where the problem occurred.  I had very carefully placed the 10 stainless steel wood screws in my trouser pocket.  It was when I went to retrieve them that I discovered the “plop..plop” sound I had been hearing was the screws falling through the hole in my pocket and into the canal.  Readers, harsh words were said!  Did you know a magnet can’t retrieve stainless steel.  Fortunately I had a few spare screws.  The screws were reinserted in sequence diagonally opposite each other to ensure the porthole went in evenly.  However the screws weren’t tightened.  Actually I loosened each one in turn and applied a dollop of silicone to the screw shaft. The screws were then fully tightened.  Hopefully the silicone will seal between the head of the screw and the hole.

Finally the pvc beading tape was fitted back into the groove to cover the screw heads.

I then wiped of any excess silicone from around the outside of the porthole with a cloth soaked in white spirits.  The blue masking tape will remain in place until tomorrow to allow the silicone on the inside of the frame to set.  I should then be able to remove the tape and any surplus silicone using a razor knife.
Now I must decide whether to give the remaining portholes the same treatment.