Rebeding hatches question

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Joebar
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Rebeding hatches question

Post by Joebar »

Hi guys!
My brother and I are the new owners of a 10 meter mid cabin.

I'm trying to reseal the skylights and I'm wondering how to "rebed" them.

Any insight would be much appreciated!

Thanks.
1989 Trojan 10 Meter Mid Cabin

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Re: Rebeding hatches question

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I made your question its own topic Welcome and congrats on the new boat.
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zedtwentyate
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Re: Rebeding hatches question

Post by zedtwentyate »

Joebar wrote:Hi guys!
My brother and I are the new owners of a 10 meter mid cabin.

I'm trying to reseal the skylights and I'm wondering how to "rebed" them.

Any insight would be much appreciated!

Thanks.
I have yet to rebed mine. They don't leak right now. Maybe BobCT or Todd can chime in here. I know Todd replaced his.

With my old boat, someone recommended butyl tape from and RV store for that type of bedding. I never tried it though.
Kegan

1986 Trojan F-27 (SOLD!!!)
1989 Trojan 10 Meter Mid Cabin

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gitchisum
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Re: Rebeding hatches question

Post by gitchisum »

I just finished re-bedding all my deck hardware with Butyl. Picked away at it over the last 3 seasons.

There are several threads on the board have good information and links. I used one of them to purchase the Butyl tape

easy to do, just time consuming. Good luck

http://www.pbase.com/mainecruising/butyl_tape this is where I purchased mine
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oil&water
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Re: Rebeding hatches question

Post by oil&water »

It's not very complicated, but does require some time and effort to complete correctly.

Step 1) Remove the entire hatch from the deck.
Step 2) Use a razor blade to remove all old caulking from the hatch and the deck.
Step 3) Use alcohol or caulk remover to clean up any left over residue.
Step 4) Make sure the hatch surface is free from any corrosion or pitting. I had to use a 4-1/2" grinder with flap disk to grind the hatch mating surface down due to the extreme corrosion and pitting on the surface. Any irregularities on the mating surface will cause water to wick through past the caulking and straight into the core.
Step 5) Use epoxy or Marinetex to seal any cracks leading into the hatch area.
Step 6) Use 3M Blue or Frog Tape around the outside of the hatch area on the deck. If there are no longer any lines on the deck to indicate where the borders of the hatch are located, place the hatch in the hole and mark the edges with a pencil. Apply tape approximately 1/8" to 1/4" around those marks. This will allow you to remove the tape and have a nice finished caulk line when complete.
Step 7) Apply a nice size bead all around the hatch mating surface. The idea is not to have so much that there is enormous amounts of squeezed out caulk to clean up. You do want enough to give you a nice squeeze out of caulk bedding around the entire hatch. Install screws on each side to pull down the hatch to about a 1/16" gap between the deck and the hatch mating surface. You should have a nice over flow of caulk around the edges now. Use a wet finger or caulk finisher to clean up your caulk edge.
Step 8 ) When happy, carefully remove the tape. Let the caulk setup overnight.
Step 9) Once setup, remove screws one at a time and squeeze in new caulk in holes and tighten the screws down to create a flexible seal around the hatch.
Step 10) Sit back and enjoy your boat.

This method is a little more time consuming but does give you a nice caulk "buffer" that has room to expand and move as the deck flexes without breaking free.

I used Loctite Marine Fast Cure Adhesive Sealant for my hatches. 3M 4000UV or 4200 would also be a good caulk to utilize. I am not a big 3M 5200 fan above the water line as inevitably we tend to remove items we see. Especially when our overweight friends step on them and break said hatches.
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BobCT
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Re: Rebeding hatches question

Post by BobCT »

I have replaced my portlight hatches and used DOW 795 adhesive. Lexan does not adhere well to 4200 so I would not recommend that in this case. There are a few issues with the portlights specific to the mid cabin:

1) They are an unsusal shape so there's no option to replace with a conventional, opening hatch without major rework on the deck and interior ceiling

2) The "glass" has a slight curve which follows the shape of the deck. I wanted to eliminate the mechanical fasteners (screws) when I had new panels made and now wish I did. The DOW stuff is incredibly strong and I would trust that alone if I could get enough weight on top while it cured.

3) There is a gap all around that needs to be filled. It's hard to get this to look good (I masked all around) and it's impossible to keep it looking good. The DOW adhesive attracts dirt just like every other white sealant I've used. I am going to get stainless steel trim rings made at some point which cover the perimeter but open to other ideas if anyone has them.

Decide now if you want to replace the Lexan if it's original. You don't want to do this again. It's not worth rebedding crappy looking ones in my opinion. Either way, make sure you seal the exposed edges of the plywood core once they are removed.

I use butyl tape as well and that might be an option here. I would be concerned about point # 2 though. The butyl would not be strong enough alone if there was an issue with the screws.

Bob
1988 10m mid cabin

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yorklyn
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Re: Rebeding hatches question

Post by yorklyn »

Bob told me about the dow 795, use it! If you cant find it locally you can order it from McMaster Carr. I did mine 3 different times before finally using the dow 795. my original skylights were held in with at least 25 screws each. I tried removing them and re-bedding with 4000uv , they leaked. then I tried a different caulk from a hardware store that someone recommended, they started leaking after a week. purchased 1/2 plexiglass online and made two new ones. tried some highly rated silicone adhesive and they were good for about a month. finally bought more 1/2 plexi and made another set (didnt want to try to adhere to old silicone) . since I was painting the boat at the time I was able to thoroughly sand and grind off all of the old adhesives and filled in all of the old screw holes . I used 3/16 inch shims to keep the skylight raised to keep it from compressing out all of the caulk. I put about 1/4 inch of adhesive completely around the lip that the plexi sits on. (make sure you tape off all of the surrounding areas including the skylight leaving just the area that you want to bond exposed. set the skylight into the adhesive (there should be about 3/16 to 1/4 gap around the entire skylight, dont worry about getting adhesive in the gap at this time) put a weight on top so that the plexi compresses down to rest on the shims. let it sit overnight. next day remove the shims. tape off the topside just like you did the underside, including the plexiglass out to the edge. caulk around the the gap up top. be sure to completely inject the caulk in the gap so that there are no bubbles/air gaps. caulk the gaps left from shims down below. Piece of Cake!
Todd Pote
1987 10 Meter Mid Cabin
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1992 Scout 15.5 Center Console

Joebar
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Re: Rebeding hatches question

Post by Joebar »

Thanks for all the suggestions!!

Since it's been nothing but rain since I started this I temporarily put the old plexi panel back in with silicone caulk.

When I have a few days with no rain in the forecast (if it starts leaking again) or after the season and the boat is shrink-wrapped again I'll restart the project combining all the best practices you guys have suggested including new panels.

Joe
1989 Trojan 10 Meter Mid Cabin

mrrudely
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Re: Rebeding hatches question

Post by mrrudely »

I know this is an old subject but just in case someone is still having problems this might help
I removed the starboard skylight and cleaned everything thoroughly
There were hairline cracks around some of the screw holes in the skylight
I let some vey thin acrylic cement flow into the cracks
I then filled all the screw holes with white epoxy
I then used 3M VHB Mounting Tape 4910 to hold the skylight in place (carefully with spacers to center)
No screws
I then masked off and caulked with Dow 795
I used black because the white never seems to stay white
So far so good
The only thing I might do differently is I might use 2 layers of tape to raise the skylight a bit
The port light (over the dinette) we are thinking of making clear and operable
Not sure how to do that yet

rr
10 meter mid cabin

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