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Hatch cover problem

Submitted by aaronpotter on Sun, 05/06/2018 - 22:33

I’m getting close to the end of my Guillemot build and had another problem pop up this weekend. I am using magnets to hold the hatch covers in place like Rob Macks describes in his book and videos. I had to heat one area to loosen the epoxy to correct the orientation of a magnet in the cover ( I’m not sure how I managed to screw that up). Once I got that taken care of and put the cover in place, I realized that the shape of the forward hatch cover does not match the shape of the deck.  The starboard sides sits very close to flush with the deck while the port side is over 1/4” high.

  When joining the deck and hull last fall, I had to do a lot of persuading to get the edges lined up.  I cut the hatches after the halves were joined and the cover sat in the shop since last October. It looks like the front hatch has flattened out or the deck was pulled out of shape when I joined the halves. 

I’m afraid I know the solution but hate the thought of heating and removing the fiberglass from the hatch cover. I’m sure the color won’t match if I do. I’ll likely try gentle heat first to see if I can get the cover to conform more closely to the shape of the deck.   My attempt at gentle heat on the hull ended up causing a bubble in the fiberglass I had to cut out and patch. 

The rear hatch didn’t have this problem but that may be because I got the magnets installed for it last fall and it sat in place on the deck.

Any suggestions before I get out the heat gun?

thanks in advance

 

Underside of hatch coverHatch cover misalignment

DonTaylor1

Mon, 05/07/2018 - 09:19

One thread out of the archives.

http://www.kayakforum.com/cgi-bin/Building/archive.pl/bid/12/md/read/id…

I built a form and recurved using a home oven to apply heat  use thin cardboard to protect the epoxy and clamp over large areas. It takes significant pressure to reshape.   Heat,  clamp and let cool for a couple of hours.   If you have to strip the hatch you can re-glass without a color change  by pulling off the glass and  not sanding through the seal coat.    I didn't have to use braces underneath but resuts may vary.

Another idea

http://www.kayakforum.com/cgi-bin/Building/archive.pl/bid/13/md/read/id…

Etienne Muller

Mon, 05/07/2018 - 11:36

Hi, Aaron. It is indeed a large discrepancy in the curve. Even if you remove the glass from the top of the hatch and re-glass it, the magnet ring underneath is probably going to make it too stiff to manipulate easily.

My feeling is that you are going to have to remove the magnet ring as well, or at least put saw cuts into it at frequent intervals to relieve the lamination stress where you want the bend to happen.

I have never tried this, but the entire lid could become more flexible, with the epoxy moving between all parts, if you were to put it in a microwave oven for a few minutes, BUT I am not sure how the magnets would react to microwaves. They may become too hot and ruin the lid entirely. A test run on a mockup would definitely be in order first. You may also ruin the oven... So at your own risk...

Also, if you strip off only the glass on the outside of the hatch to reestablish the correct curve, be aware... In my experience, the glass/epoxy layup shrinks a little as it cures. The result may be that your curve reduces as everything goes off. If only one side is to be reglassed, my instinct would be to put in a little more curve to allow for this distortion.

You have an interesting conundrum here. In the end you may find you have to disassemble the hatch altogether into it's component parts, right down to separating the strips, place a curved sheet of some sort over the deck, and rebuild the hatch from the ground up, using the deck as a former.

Good luck... Etienne

JayBabina

Mon, 05/07/2018 - 18:22

Looking at your two pictures it looks like your deck has a V shape in the center of the rise.

That cover did fit perfectly at one time? It seems like you might be able to put one kerf cut right down the center of the cover maybe with a radial arm saw or router and bend it right into shape. If you clamp in some blocks of wood, you could even do it with a hand saw. You would fill the kerf with epoxy and fortify the cut. It just looks like your curve from the center out is ok. And if it doesn't work perfectly, nothing lost. You would still have to do some surgery no matter what route you take.

Thanks for the links. Not sure why I didn’t think to search the old site. I’m sure there’s no mistake I can make that hasn’t been discussed here before. But I’m not going to take a chance at being the first to put magnets in the microwave!  

I put a couple of ratchet straps over the hatch and applied a little heat with the heat gun to the outside. With a little persuasion, the hatch conformed to the deck shape. I’ll leave the straps on for a while and see how much it springs back. It looks like I did stress the fiberglass as described in Rob Macks’ reply in one of the links. That will nail down the location of the webbing loop for the handle. I don’t think it will be too noticeable as long as it doesn’t get worse. 

I’ll post an update when I it finished. Hopefully I don’t have to go to the extreme Et mentioned. 

Rob Macks Laug…

Thu, 05/10/2018 - 09:06

I'd remove the glass inside the magnet ring with a heat gun. This will make the cover more flexible.

Cut the edge of glass inside the magnet ring with a utility knife. 

Shield the magnets from heat as you remove the glass with needle nose pliers.

See if the hatch cover will be pulled into the right shape by the magnets by placing it in the hatch opening.

Apply new glass and place the cover in the opening with plastic wrap between deck and cover.

The magnets should hold the cover in shape as interior glass cures.

If not, apply a couple clamps to squeeze the cover into shape off the deck as interior glass cures.

All the best,

Rob Macks

Laughing Loon Custom Canoes & Kayaks

http://www.laughingloon.com/

207-549-3531

 

“People who say it cannot be done should not interrupt those who are doing it.” - Chinese Proverb