Hatch Cover Rebuild

[Bark]

My hatch cover has been leaking and I have taken it apart to rebuild/refinish. It's pretty simple--teak, four sides with mitered corners, a center wood cross piece, and two glass panels that lay on top. The various pieces are all tongue & groove fitted. I've taken it all apart and am stripping varnish and generally cleaning it up.

Basic woodworking question: when I re-assemble, should I glue the joints with wood glue or should I use epoxy? Or should I use anything at all in the joints other than the screws that were there? The piece obviously gets a lot of exposure, so I wanted to weatherproof it as well as possible. Suggestions? Thanks, all.

[Ian McColgin]

I don't like hatch covers with mitred corners. Prefer box finger. I also found that the minute there's two pieces of glass, there's often leaks.

Is it glass? Or plexi or lexan?

How classic is the hatch cover? Goblin had beautiful old hatch covers with nice round glass ports in each one. The corners were mitred and the top planks splined and the hatch inset with a bronze ring that was terrific for trapping water.

My general approach to that rebuild was to redo the wood parts with sitka flex and well bunged screws. I set the glass on and surrounded by silicon and added silicon before screwing down the rings. Held up for the remaining ten years of Goblin's life.

But if there is nothing that special about the hatch, I preferr to make a new one. My favorite easy to make nice looking tought as nails approach is to make the rectangular sides with box finger joints with either sitkla flex or epoxy as an adheasive. The top will be one piece of lexan bedded nicely in silicon. You may want to just lay the lexan on a flat top of the frame or you may want to inset it a bit, but either way the lexan should stand at leas a tad proud of the wood with the top edge relieved, so water cannot stay there.

It's nice to avoid hazardouse slipping when you step on the hatch to put some teak slats running fore and aft. The two at each side and the ends of the others can be a good place to put the screws that hold the lexan down, bunged over and all tiddley.

I've usually put a couple of screws into each slat up from the inside just to give a side to side strength against slippage but a neat job with the silicon adheasive might be strong enough for all I know.

Either way, g'luck

[Dan McCosh]

For what it's worth, one of the few places I've experienced epoxy failure was a glued-up hatch, which got too hot in the sun.

[Bark]

The glass panels are actually plexiglass, and I plan to replace them. They're set into a recessed edge with screws all along the edges of the glass (with exposed screw heads). Last year I pulled each screw and squirted goop into each hole before resetting, but it leaked worse than ever. The seams between the miter cuts are filled with what looks like black sikaflex or something.

So, assuming I use this existing hatch cover, should I just use good wood glue when I reassemble? Also, any thoughts on how to have new plexiglass fitted (it's curved)? Thanks for the input.

[Bark]

Ian - I just re-read your post and realized you answered some of my basic questions, i.e. using Sikaflex and adding some teak strips, which the glass screws would be screwed into. Thanks.

[paladin]

first....whatever construction methoth that you use...don't use plexiglas...please use lexan, the thickest piece you can fit. Also do not drill holes through the lexan to screw it down with the screw heads against the lexan...instant leaks...
Drill all the holes slightly oversize, bed the lexan in sikaflex or whatever so that some comes into the screw holes, fashion a wood frame or slat to cover the edges and screw holes in the lexan and drill matching holes in the frame, then more sealant and put the frame in place over the lexan and insert screws..tighten carefully....ya dunno wanna crack the plastic....use bronze or slightly smoky lexan.......

[Bark]

Thanks, Paladin. Yeah, the screws heads were previously right on the glass and it did leak. And I cracked the glass when I rescrewed them down. I like the idea of a wood slat over them. Any idea where I can get Lexan (it would have to be curved to fit)?

[Paul Scheuer]

The early King's Cruisers had plastic windows. I say windows not portholes or lights. These were as big as the windows on a 50's car. At least four feet long and about a foot high. When I saw the damage to the splined mitered frames, I did a number on the thermal activity. Here in the midwest with a range of 100 F over the year, the motion was at least 1/4 inch over the long dimension. The frames actually blew apart at the corners. Slot the holes, plan on motion, and a way to keep "gunk" out fo the voids.

[Buddy]

One caveat- yeah, Lexan ( polycarbonate) is more nearly unbreakable compared to Plexiglass (acrylic), but it scratches more easily and worse, clouds up rather quickly when exposed to daylight. Sitting flat looking right up at the sun ' it couldn't be in a worse place. I'd really prefer to use a thicker, and yet still less expensive, piece of acrylic, say 1/2" thick to handle any stepping upon it, with those wooden wear strips to prevent stratches and to provide footing. Really first class would be thick, laminated safety glass, but a tad more expensive than Lexan.

[Ian McColgin]

You're not doing astro navigation through the hatch. No matter how cloudy it may get, the optical quality of looking up at the sky is not very important. If the hatch is right over a berth and you really prize a perfect view of the full moon that short time it may shine through the hatch, well maybe.

Lexan. I should have mentioned the reason for the slats and Paladin's remark about the hole being a tad loose. But all in all, lexan is easy to work with and very strong.

Slight aside: Guy on the Vinyard did lexan shutters and ports for a good chunk of the fishing fleet one winter and was left with some long narros sheets. He made a flatty skiff. Wood for chine log and frames and transom. Lexan sides and bottom. 'Twas really strange to see a guy puttering about the harbor, standing in a collection of verticle sticks holding the handle of an outboard.

[Bark]

Thanks, Buddy. Good thoughts. I'll see what's available. Still not sure how the glass (or Lexan, or acrylic) will curve and fit into place.

[Bob Smalser]

Originally posted by Bark:
--teak, four sides with mitered corners, a center wood cross piece, and two glass panels that lay on top. The various pieces are all tongue & groove fitted. I've taken it all apart and am stripping varnish and generally cleaning it up.

Basic woodworking question: when I re-assemble, should I glue the joints with wood glue or should I use epoxy? Or should I use anything at all in the joints other than the screws that were there? The piece obviously gets a lot of exposure, so I wanted to weatherproof it as well as possible. Suggestions? Thanks, all.I take it this teak frame has simple mitered corners that are merely screwed together as the joining method? Were the joints originally glued? What does the old glue residue look like?

Miter joints fail relatively quickly because endgrain doesn't glue well, there is relatively little glueing surface, and the joint breaks apart with seasonal movement. As the wood shrinks across its grain, the corners of the miter pull away from the joint. They all fail, eventually...even the epoxied ones.

Do you have access to a table saw and a scrap of 1/8" luan doorskin? If so, we can spline them to double your gluing surface prior to reassembly with the original screws.

[ 01-12-2004, 07:34 PM: Message edited by: Bob Smalser ]

[Ian McColgin]

Lexan is reradily bent with a little heat. I've used a hair dryer but if you can make friends with a local glass guy s/he can tell you. Easy does it. A nudge more heat on the concave side.

There are blade that are most suited to cutting any plastic - lexan or plexi. I use a saber saw. The blades are not metal cutting blades but they have about that many teeth per inch. Rather they have virtually no kerf but the blade behind the teeth is ground back a little so that the whole blade is thinner than the cut. Even at that with plexi and sometimes with lexan you end up leaving a sort of molten set of chips in the cut and on completion you have to snap the cut apard and then dress the edge.

The more I think on your project, the more I recommend making a wholly new hatch cover and make box finger joints. Even a splined mitre joint is not very durable.

There are router jigs and one can make a simple jig to get out the fingers on a table saw but this job is not worth that much work. One finger sticking out on the fore and aft piences and a slot for it on the athwartships pieces - I think that looks a tad better than oriented the other way. If you're slick, dove tail it a little. The chisel you want can be viewed in the little essay on mortice and tenion. Really, four such joints are not much work. Make it five so you can proactice one on some scrap and be sure you know how to scribe it for a perfect fit. Even at that, maybe an hour or so of peaceful tappitytap.

G'luck

[Bark]

It surprised me, Bob, that there didn't seem to be any old glue residue at all. It seemed as if the screws (just one per joint) were the only mechanism for holding the thing together. The hatch cover is standard-issue Cheoy Lee from '63.
Sorry for my dimness, but would the splines and their increased gluing surface essentially just help fill the void between the miter joints?

Ian, building a new cover sounds like a lot of fun. If I don't do it for this one, I may try to build a new chain locker hatch, which doesn't have sloping sides and seems a little more in line with my, uh, limited skill set.

Great stuff, everyone. Thanks.

[Bob Smalser]

Originally posted by Bark:
[QB]It surprised me, Bob, that there didn't seem if the screws (just one per joint) were the only mechanism for holding the thing together. The hatch cover is standard-issue Cheoy Lee from '63.
Sorry for my dimness, but would the splines and their increased gluing surface essentially just help fill the void between the miter joints?
[QB]to be any old glue residue at all. It seemed as

Personally, I think miter joints done without a half lap (sorry, don't have a pic...will have to cut one sometime) are junk...even the splined ones. I too would make a new hatch using dovetails or box joints.

But you can get some more life out of this one by splining with 1/8" or 1/4" exterior ply scraps on the TS and gluing and screwing. I've no experience using 5200 poly as a glue, but it has a good reputation and may serve as a gasket of sorts for when those miters begin to gap at the ends under the hot sun and be a good idea. Just make sure the bonding surfaces are perfectly clean...and use alcohol on that teak endgrain immediately prior to gluing.

Otherwise, I'd use epoxy in an unthickened coat followed immediately by a thickened and dyed coat and light clamping on a dead flat surface like MDF covered with wax paper.

Check your hatch opening for square before clamping, tho...as if it's not square you will have to match the error. One way to do that is to clamp it in place.

[Ian McColgin]

There likely was some glue but very thin and with this many years . . .

If going for reassembly, I'd use either epoxy or sitkaflex if it's not teak. If teak and you want to use epoxy, besure to acetone the surface to be glues a few minutes before the job to pull the teak's oil out and give room for the glue.

I love epoxy on an end grain like this. I'd put down a coat or two of unthickened epoxy, very neatly only on the mitre, tape the sides and be neat. Sand between coats. Once the end grain is as saturated as can be, then the two sanded surfaces can be brought together with great confidence. If you've got good shape, the final glue coat may not need much thickening and will become invisible.

The big problem people have with end grain is not getting a soaking coat in and cured first.

Have a dry fit set up accuratly with holes for the corner screws - two in one direction and one the other per corner - already bored and countersunk to wherever the bung will go.

As hinted above, I'm not a fan of splines or biscuts, perhaps because I have neither a biscut cutter nor a TV. Epoxy can be pretty slippery and splines can help with allignment, but your screws will do that for you. Just clamp carefully.

Make sure you can dry fit and clamp and lightly screw it all together and that the lexan fits.

G'luck

[Bob Smalser]

The big problem people have with end grain is not getting a soaking coat in and cured first.
Thanks, Ian...will try that one next time. I usually use heat to soak the epoxy in good, but I'd be reluctant to do that on oily teak or other tropical hardwood.

[Ian McColgin]

Heat generally accelerates the epoxy cure, so you may actually have limited the uptake in the grain.

With the exception of CPES, which is a sealer not a glue, epoxy penetration in normal side grain is actually minimal. That's why some years back WEST changed the 's' from the original 'saturation' to - anyone looked at a lable recently? I use the stuff daily and I think it's now 'system' but would hate to bet my life this early in the morning.

But WEST and the other thinner epoxies have lots of places to go in end grain. I suppose for maximum saturation you could use CPES to seal and then use Mr. Smith's epoxy as a glue.

I've not had an end grain joint fail, even with teak. Just also remember the acetone bit with teak or any oily wood. Acetone won't remove all the oil and if you put too much time between the acetone wipe and the epoxy, oils in the wood will drift back to your gluing surface, but 2 to 5 minutes before seems give enough time for the acetone and any oils it has captured to evaporate but not so much time that oils beyond the acetone's reach can float back.

With end grain the soak of everything is a bit further depending on the wood grain, but in essence gluing happens with the surface molecules.

[JimConlin]

There are varieties of both acrylic (Lucite, Plexiglass) and polycarbonate (Lexan, Makrolon) which are claimed to be more abrasion and weather resistant. I've been very disappointed with polycarbonate that weathered badly in just 3-4 years.

[Buddy]

I see this project is still being discussed. Another vote against polycarbonate in this appilication I see. Regarding the curve. You can smooth a cotton teeshirt over your old hatch and glass, use as a form and put the new flat pieces of plexiglass on top in an oven and they will drape to the curve. Great trick. It might be accomplished with a hand held heat gun used carefully as your hatch can't be done half at a time in your oven. The door won't be closed and you're only talking 250 degree heat.

[Bark]

More good information. Thanks again, everyone.