Where the wood meets the lexan...

[Abrain]

I'm repairing my hatch as its all wood and only needs new plexiglass. My lack of knowledge on this project is what is used between the wood and glass area, what compound should be implemented to make it water tight?

[model 10]

Which are you using, Lexan or Plexiglass? 2 different materials. I think plexiglass stays clear longer, it also polishes better.

[Abrain]

I'm using a high quality uv scratch resistant Lexan.

[Chenega]

I would suggest using Dow749 (McMaster.com). Be sure to allow room for the Lexan to expand in heat and not blow apart the wood frame. About 1/8" all around for 2 ft square panel. M Then start by masking off the area on the Lexan where you don't want the bedding. Lightly scuff the Lexan surface with 280 - 300 grit paper that is to be bedded and clean with alcohol. Mask off the areas on frame and Lexan (inside and out) at edge of bedding seam. Make sure all areas you don't want bedding are masked. Apply liberal amount of 795 and press Lexan into it. Use plenty so you have no air pockets. Quickly tool off excess using plastic spreader before it skins over and carefully pull the masking tape. Follow up the next day by lightly hitting the bedding with a scotchbrite pad - this will flatten out the gloss on the silicone. This silicone is used for glass panels on high-rise buildings and many boat hatches on the market. Caution... It is very black! Keep it off older gelcoat!

[Chenega]

Originally Posted by Chenega

I would suggest using Dow749 (McMaster.com). Be sure to allow room for the Lexan to expand in heat and not blow apart the wood frame. About 1/8" all around for 2 ft square panel. M Then start by masking off the area on the Lexan where you don't want the bedding. Lightly scuff the Lexan surface with 280 - 300 grit paper that is to be bedded and clean with alcohol. Mask off the areas on frame and Lexan (inside and out) at edge of bedding seam. Make sure all areas you don't want bedding are masked. Apply liberal amount of 795 and press Lexan into it. Use plenty so you have no air pockets. Quickly tool off excess using plastic spreader before it skins over and carefully pull the masking tape. Follow up the next day by lightly hitting the bedding with a scotchbrite pad - this will flatten out the gloss on the silicone. This silicone is used for glass panels on high-rise buildings and many boat hatches on the market. Caution... It is very black! Keep it off older gelcoat!

Dow 795 not 749 - oops typo!

[Abrain]

Isn't there another solution? Wonder if I can use the butane tape? I'm not so sure yet about 749.

[jgbrown]

Originally Posted by Abrain

Isn't there another solution? Wonder if I can use the butane tape? I'm not so sure yet about 749.

Butyl tape is great.
I prefer window specific. Black with a rubber core to prevent it all oozing away.
It doesn't hold alone. Mechanical fastening required. Gasket(Catalina window style) or mechanical fasteners required.

[Driftwoods]

I just started reseating the plexiglass in my hatches with GE SSG4000 UltraGlaze Silicone Structural Glazing Sealant. I have Bomar hatches and this is what they recommend. I am working with aluminum instead of wood but I don't know if that makes any difference. Pretty easy to apply but you gotta be careful since it seems to want to get everywhere somehow but you can clean up pretty easily with acetone before it cures.

[Abrain]

Thanks for the info people, but I truly will never use silicone products on my boat. I'm going to use butyl tape and see what happens.

[Driftwoods]

I love me some butyl tape, rebedding all my deck hardware with it right now. I had to go silicone on the hatches since the acrylic floats in there with no fasteners to hold it down. Unfortunately, sometimes silicon is not the best answer but the only answer.

[Beersmith]

just rebuilt my hatch using acrylic and Sikaflex 295UV for the compound based on much research.

Would have used butyl if the acrylic was thru-bolted, but since it is merely screwed in I went with the strong Sikaflex