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Figure 1: Condensation forms on outside hatch cover and water runs overboard.


Eliminating Dripping Hatches


Reduce condensation down below by building a hatch cover over your hatch cover.


Cold weather is around the corner


and some interior surfaces of a boat are bound to form condensation. One of the prime culprits of this is the hatches. Aluminum is a good conductor of heat, Plexiglas not so much. However, hot, moist air will condense on both of them when it is cold enough outside, particularly if we add to the mix a source of water vapor — that would be you and me. The situation is this: cold air outside a warm cabin plus one or more intrepid sailors exhaling a glass


By Jack and Alex Wilken or so of water a day and, voila, we have water dripping from the hatches, a most unpleasant occurrence both for gear and people. The situation is worse if you are living onboard. One solution we have found is


a hatch cover; kind of a hatch over a hatch (Figure 1). The condensation forms on the inside of the outside hatch cover rather than inside the boat, and the water runs overboard rather than dripping inside.


Materials: For your hatch cover you will need 2 x 6 Cedar planks (or some other wood), ¼” thick Plexiglas, stainless steel flat head wood screws (12 each) 2½” x #10, 1” x #10 (amount depends on size of cover) and water proof yellow wood glue. Cedar is more expensive but, because it is more rot resistant, it will not need to be painted. You can use fir, however it is less rot resistant and should be painted, as is true for most other woods. Plexiglas is actually a brand name for what is generically known as acrylic glass and has also been sold as Lucite or Perspex. We call for ¼” thick with the idea that you will not be stepping on it. If you will be stepping on the cover, 3


/8 ” should be


okay for 18” x 18” or smaller and ½” if it is 24” x 24”.


Tools: You’ll need a tape measure, a drill motor, 1 a 7


/8” and 7 /32 /32 ” drill bits and ” drill bit for plastic, a counter


sink for the screws, a saw of some kind, perhaps a wood plane, something to screw in the screws and a pencil.


Construction: 1. Measure for the size of the cover(s) you will need. The cover should be about 1” or 2” larger than the hatch.


2. Set one of the athwartship planks on the curved part of the deck and scribe the plank using a pencil on a piece of wood that is the thickness of the gap at the end of the plank (Figure 2).


Figure 2: Scribe contour of the deck onto plank and cut. 48° NORTH, DECEMBER 2011 PAGE 36


Figure 3: Screw and glue corner joints.


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