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the dream of dawn

How not to retrofit a hatch: Destruction

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Here's where we learn what's inside the hatch structure. Removal of the wood trim reveals a fairly uneven gap, with unfriendly angles, between the deck piece and the liner piece. Apparently both pieces were made with flanges that were supposed to line up, but some grinding had to be done to make the original hatch fit.
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To make the new hatch fit, we need to remove the inner lip to create a flat platform, widen the fore-aft dimension of the opening by 1/2 inch, and narrow the width by 1 inch. Cutting stuff away was straightforward, using an oscillating tool with a carbide all-purpose blade. Except that the liner riser ends up with weird acute angles. Now we see that we also need to bridge a gap between the forward edge of the deck opening and the liner opening. Another surprise was that the empty space between the liner and deck contained some old mud-dauber nests. Somehow, this murky inner space must have a passage to free air, somewhere. Or had one once. It's hard to see where, though.

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The horrors of the next few steps were not adequately captured as images. I fastidiously masked-off the surgical site with masking tape and lots of craft paper. Then ground the platform area down to bare fiberglass with an angle grinder. Doing all this while the boat floats in its slip in the marina is kind of sketchy and possibly against the rules. I did get the hairy eyeball from the marina manager, but no direct admonition. And I made a big show of chasing down all my work with a vacuum. However, I didn't feel that I could grind away lustily, as I should have, as things devolved. To fill the gap along the front, and solidify the whole piece, I got the bright idea to squirt a can of insulating "crack filler" foam down into the annulus. Hopefully this would help to bond the hull and liner together, and add some much-needed insulation to the cabin-top. (Well, it seems to have worked in the quarter berth project, a few posts ago...) The plan was to then trim the foam and lay down fiberglass on top of it. To narrow the sides of the opening, I built up an in-situ mold with strips of wood and a handful of beeswax, which I happen to have a lot of in the shop.

This is the point at which it would have been better to simply cut away the entire inner riser and fashion a solid square-angled one of the proper dimension in its place. That could then be simply bonded and faired to the deck, and a trim piece framed in below.

To continue... spray foam is always a minor disaster in itself. But it went in without too much fight. A whole can of the stuff went down into the mysterious gap. Then I went away on the paddelboard for a few hours to let the foam set up. I trimmed the foam as per plan, ensured that the side-mold pieces were well-waxed, and started laying down strips of fiberglass cloth that were pre-impregnated by soaking them in a tray of freshly-mixed epoxy, then "squeegied" off with gloved fingers. This is an extremely messy way to do a lay up, but worked for me before, somewhat better than trying to "paint" epoxy onto the glass in-situ. Which is why I spent so much time masking-off the work area. I put down eight layers of glass (basically the whole package that I had), forced myself to stop messing with it, and went home for the night.

The next morning, it was immediately obvious that something was wrong... the spray foam had continued to expand out of the gap in a couple of places, creating weird bubbles in the layup! Apparently trimming it off had reactivated it in some kind of delayed fashion. Should have waited another day. Well, nothing that a grinder and another lay-up session won't fix. Then I discovered the rather obvious fact that the masking tape and craft paper that I had used were perfectly capable of absorbing excess epoxy resin and had become bonded to the deck in places. !$#^ Not only that, but excess rivulets of epoxy had leaked through and dribbled down the sides of the deckhouse. #&^%$!!!!!

Well, again, nothing that grinding and sanding won't fix. The gelcoat on deck is badly crazed and pitted anyway, and addressing it is the main goal for the next haul out. But this project was rapidly escalating in every direction away from the hatch opening. And a major ugly screw-up. I spent another couple of days trying to clean up the mess as best I could, and filling and fairing the new flange. Waiting a day at each step for the epoxy to set up was rapidly chewing away at the available project time window. So I stopped at the "good enough to get by until the haul-out" stage. As defined by wishful thinking. I trimmed the new flange into the required dimension and slapped some IP2000 over it.

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And before spending another week making this perfect, perhaps we should figure out if it's even going to work?

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Updated 09-23-2018 at 12:32 PM by toddster

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  1. bigd14's Avatar
    Ahh, this got me laughing out loud. I have had so many similar experiences. It never goes as planned!

    Nice work in the end though. It looks like it was designed that way.