Deck Hatches

[SV_Pegasus]

Hi Tony,
It's not the crazing from the Sun, but from overtightening countersunk flatheads - that's what happened to mine. This summer I'm redoing them with round-head screws.
Sam

[kelpie]

Sam,

Interesting on the screw situation you've encountered. I don't think that's my situation, but should be able to tell more once I get the trim removed so I can see things better.

I found this pretty extensive discussion on the relative merits of polycarbonate (lexan) vs. acrylic on a related "Cruiser's Forum" boat site. Some pretty heavy-hitters with lots of experience with hatches seem to strongly favor acrylic over lexan:

http://www.cruisersforum.com/forums/f55 ... 24956.html

[ricardo]

I did rebuild my three original hatches and there were no screws holding the Lexan, only bedding compound. If you keep the original design you will have to stick to the original thickness which is 3/8" (the frame is built that way). I think that with such thickness, Lexan is a must. The only downside with Lexan is the softness of its surface, that's why it bends but rarely cracks. This may be hard to find but there is a Lexan version with a scratch resistant surface. It was called MR-10 at the time I did my job. Very Important to find a bedding compound that's 100% compatible with Lexan. Some will not stick well, others will burn the surface.

Good luck!

Richard

[warmrain]

Our hatch material is literally bullet-proof, it is armored car window material. 3/8" thick only because the hatch is built for that material size.

If you are going to keep the hatch varnished there is no reason to epoxy the bungs in, in fact you don't really have to use glue. In decks and the like epozy is required, but in hatches, to save the effort of removing them, just tape them in, trip send and varnish over them.

~Cars

[SV_Pegasus]

Cars,
It's a bit off-topic, but what do you use for weatherstripping your butterfly hatches? I need something 1/2" x 3/4" or so.
Sam

[warmrain]

Good question. I haven't had to replace mine yet. But when I had to replace the stuff on my icebox door I found an industrial outfit that supplied such things, went to them with a description of what I needed it for and a dimension and got the perfect material. Dense, black, small celled and dense... a sort of foam. I would probably start with an interenet search for such a supplier...

~Cars

[SV_Pegasus]

I've been looking on the internet. It may end up being automotive trunk weatherstripping. My next quest is for bronze round-head square bit wood screws to hold down the hatch "glass". No luck yet.
Sam

[kelpie]

I wound up rebuilding the forward hatch and it turned out great (so far).

I made sure to obtain cast acrylic for best sun longevity and sealed it using #795 Dow Corning silicon glazing sealant.

Since the hatch was flat, I didn't drill any holes in the acrylic nor did I put any screws through it--so it is free to expand and contract and there is less possibility of it crazing from stress at the holes. The top wood strips over the edge of the acrylic are sealed with the glazing sealant and screwed and bunged to the hatch frame.

When bedding the acrylic to the lower frame, I stood on the acrylic (in socks) and shifted my feet around a bit to get all the air out from underneath the edge of the acrylic and achieve a solid coverage of the sealer.

I also left the surface protector on the acrylic wherever it wasn't in contact so as to protect the see-through portion of the acrylic from scratches or wayward sealer.

I chose untinted acrylic.

[kelpie]

Here are some photos showing the rebuild in progress.

The first one shows the acrylic with sealer underneath, but not in the outer edges or on top yet. There is some gap around the edge so the acrylic can expand.

The other shows the #795 glazing sealer tube (from which came the black under the edges of the acrylic on the previous photo) and how it looks with the top wood edges back on, but no bungs yet.