Mushroom Vent

As you might recall, this summer we removed the diesel heating unit from the boat.  This left us with a lot more room but it also left a six inch hole in the cabin-top where the old “chimney” went out.  Originally I wanted to add a dorade vent to match the starboard side vent.  The more I played with the idea the less I liked it.

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I’m sure it would have worked out well if I wanted to cut off the molded fiberglass chimney and fiberglass a dorade, or cut off both of them and put two teak dorades in.  However all of that gets expensive!! One thing we don’t have a lot of is money to spend on things that aren’t safety related.  (I’m not talking about West Marine’s idea of safety, I’m talking about a good seamanship type safety – keeping the water out and the air in!)

Anyhow, I thought that maybe a little solar vent would be perfect for this area!  But all the solar vents are 8 inches or bigger 😦

At last I came upon a mushroom vent.  Its still ventilation, just not forced.  It also can be tightened down from the inside of the boat and becomes completely water tight.  This I like.  I also like that it doesn’t need to be closed in the rain, just on a rough passage.

Here is the hole that we had after taking out the heater:


I decided to finish the exposed fiberglass by filling and fairing everything with epoxy.  We will then paint it to be a continuation of the headliner.  Here is the first bit of filling:

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After quite a bit of sanding, filling, fairing, sanding, and on and on I got to a place where the vent could actually be installed.  I first countersunk the fiberglass where the fasteners would go through and dry fit the installation ring:

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The ring is actually meant to be a finishing feature on the inside of the boat but that obviously does not work for us.  I decided that we needed to keep it primarily because it does a good job of pushing the insect screen up and keeping it in place so no critters can find a secret way in!

Here you can see the instalation.  I used white Dow Corning 795 as a sealant both under the plastic ring and under the metal flange.  This is essentially a double seal.  The picture to the left shows you the insect screen I am talking about. To the right is what the vent looks like fully installed.

I have a bit of work ahead of me in order to finish the fairing process on the headliner, but here is a picture of the progress so far:

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You can clearly see the handle which allows one to close the vent off from the inside.  Once I finish the epoxy work this will all be smooth and painted white along with the headliner.

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