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'70 35-2 Companionway Slide Hatch Rebuild

Farlander

Member II
The idea was to post here, get advice, then undertake the project, but I skipped ahead. I blame public education.

The companionway slide was rotted out. It consisted of a piece of 3/4 plywood framed in by some teak slats, two of which were cut in a curve. The old ply was curved as well, and the question arose, how do I put a permanent curve in a replacement sheet of 3/4" plywood?

After gleaning the internet and friends with knowledge, I decided the only viable option for a guy who had just moved across the country and sold all his tools was to use 3/8" ply, double stacked, glued together while under tension. The idea being once the glue cures, the pressure could be released and the board would hold it's curved shape.

I used two ratchet straps to apply the tension. The boards were center marked and clamped at that point. The 'inner' board of the curve was cut slightly shorter than the outer ply, to allow room for the strap hooks to clear the inner ply. Tite bond III waterproof wood glue was used.

The piece has now been cut down to the proper size. The curve held!

Next phase is to sand the pieces bare, then epoxy the ply and teak, assemble with screws and more epoxy, than varnish (or other similar product?)

Open to suggestions for better finishing methods as well as ways it could have been done better.

Thanks!
 
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tenders

Innocent Bystander
I like that ratchet/strap idea. How much springback was there once you removed the strap? (Meaning, if you had 3 inches of curve bent into the piece with the strap on, how much was lost when the strap came off?)

I had to induce a curve on a substantial chunk of replacement plywood core underneath my deck-stepped mast, spanning the raised area of the deck. I gave it my best shot by wedging the edge under the lip of the deck and weighting it with bricks and buckets of water - essentially curving it in place. It seemed to work, the deck is rock-solid and hasn't budged or creaked in three years. However, there have got to be voids in there somewhere and if I had to do it again I think I'd cut a series of curved forms out of a couple of 2 x 8s with a bandsaw, and clamp the layers of new plywood along that curve while the epoxy set up. Then, once the epoxy had cured, remove the forms and drop the piece into place. But I don't know how much springback there would be after the form was unclamped from the piece.

Your process removes the need for the curved form but probably introduces some interference between the strap and the wet epoxy as it's setting up. This may not be an insurmountable inconvenience...I'll keep it in mind when my deck needs to be replaced again in 2060 or so.
 

frick

Member III
cold pressed plywood

what you discovered is a cold pressed plywood technique.
Well done.

Rick
 

tenders

Innocent Bystander
I was familiar with the concept of cold molding, but didn't think to apply it at the time since it was surrounded by fiberglass! As I understand it, cold molding maintains the attachment of the epoxy/wood structure to the form (ribs/stringers) so springback isn't a concern.
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
For a hatch with a radius you can do that with acrylic, too (3/8th max). Just bend to the frame, clamp, and put in the sun.

So says my plastics guy.
 

Farlander

Member II
Curve Rebound

I thought of using 3/4 ply with straps and leaving it out in the back of the pickup for a week or so in SF (cold, rain, sun, repeat) to see if the shape would take, but ultimately the two pieces glued ply were the way to go.

I expected the boards to rebound a lot, so I over curved the piece. Over a 3' length, I put about a 2" curve in the ply, and it did not rebound at all (1/4" max if anything). I figured during assembly it would be easier to force the wood back to it's original shape slightly rather than having to bend it more. In retrospect, I should have made the curve the exact same form as the original.

I used this video as a guide and saw the rebound was pretty extreme, thus the over curve, but it looks like the steeper the curve and the thinner the pieces of laminate are used, the more rebound. https://youtu.be/g0ikg9NdUvM

Note: The original ply was actually 5/8", so I'm going to try to shave an 1/8" off the teak frame pieces to sink the center ply in flush.

Merry New Year,
 

Farlander

Member II
First time with West epoxy

On good authority I decided to coat my freshly sanded sliding hatch with west 105 and 207 special clear. I would say the experience was just short of total disaster. First off, I used a 'Fooler' paint brush from West Marine. Big mistake. Maybe that's why they call them the fooler, because I do feel like one. Bristles were being left behind in the thick epoxy and every attempt to recover them meant more strokes, and more bristles left behind. Eventually I gave up.

Second, the resin mix was thick, like syrup, and I had a woefully insufficient amount already mixed to coat the piece, or so I thought. I hurriedly mixed up some more and began literally pouring it onto the hatch top. Big mistake. By the end I had so much sloppy goop excess it was dripping off all four sides.

Big mistake number one I forgot to mention: do not shake the cans.... doh... force of habit I guess. Tiny air bubbles were visible in the mixture before I even started applying.

So, my advice to others is, go slow, mix more than enough to start but don't plan to use it all, use a GOOD brush, and DO NOT shake the cans, and watch the west video AGAIN.

We'll see how hard sanding or scratch padding is going to be on a goopy thick layer of epoxy tomorrow... Happy New Year!
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Kevin A Wright

Member III
If others are looking for an alternate method, I had access to a piece of 5/8" teak ply so simply cut 1/8" kerf cuts on the inside every 3" about 3/4 of the way through the plywood. That gave enough flex that it easily formed to the new teak frame I had built. I then filled the kerfs with 5200 and ended up with a 'teak and holly' interior even though the exterior looked to be solid teak. In 25 years of use nobody every noticed that the inside and outside were different. I used traditional marine spar varnish to finish it but had a dodger which kept it fairly well protected, but still had to refinish every other year or so.

Kevin Wright
E35 Hydro Therapy
 

JPS27

Member III
I made a new sliding hatch top similar to how Kevin did his for last winters project. I used teak and holly sole. I don't think my kerf cuts were 3/4 of the way through for fear of snapping it, but you need enough to make sure it bends and doesn't break. I snapped a couple of scrap pieces while I tried out the approach. And I used glue and dowel inserts to secure. I filled the kerfs with epoxy. I don't have pics of what it looks like, but it looks great underneath and on top.

Here the link of helpful comments from my original post on the topic.

http://www.ericsonyachts.org/infoexchange/showthread.php?15157-Companionway-hatch-veneer-top
 

tenders

Innocent Bystander
I’m sorry this was your first experience with the miracle known as West System epoxy. Don’t give up on it yet, but maybe temper expectations as a final coat for anything. The allure of the 207 “special” hardener is strong, I know, but I find that it is rarely a great solution for exterior surfaces. It does technically hold up somewhat better than varnish, but only somewhat, and when it fails it looks terrible (gets cloudy/milky white), cannot be repaired very easily, and is a great deal of work to remove. I would not have used it like you did.

I do use 207 occasionally on items that aren’t constantly exposed (ie, my wooden tiller and inboard wooden parts on my Dyer Dhow, which is stored upside-down), but I overcoat it with several layers of spar varnish that is easily scuffed and recoated every other year or so.

It is a very good primer for paint. It lives under several coats of Perfection two-part paint on my wooden spreaders.

But in other projects, I mostly use the 205 Fast hardener unless it is very warm out or I’m mixing up a big batch that I expect will take a long time to apply. Not very often, in other words.
 

Farlander

Member II
Update:

Potential disaster. I went to install the new hatch last night which was glistening after 2 coats of west epoxy and 3 coats of epithane varnish. The hatch would not fit down over the metal slide tracks. I forced it, and ended up getting it wedged in place, forward of the hump that is the 'stopper' for the companionway slide. I did not foresee this issue and as a result, I damaged my new hatch and may have permanently ruined it. In retrospect, I believe the only way I could have gotten the hatch on would have been to remove all the screws on one track, set the hatch in and slide all the way forward, fasten rear screws, slide all the way aft and fasten forward screws. As it is looks like I'll be using a crowbar and a sledgehammer to try and salvage what I've got. 2 months of work.... woof.
 

Farlander

Member II
All is well

All is well in hatch world, I was able to gently pry off the new hatch and reset it in the proper position. Fitment is good but could be better. She slides and is waterproof. Amen.

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Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
That's a very shapely... hatch!
:)
Seriously, now just keep the cover on when not using the boat to extent the time to re-varnishing.
 
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