Lexan Bonding

[Celestialsailor]

Originally Posted by Maine Sail

Did you even read the thread? We have one manufacturer of hatches and a guy who worked for Cyro for 13 years and who owns the worlds largest hatch repair facility giving advice here. These are not back yard scientists these are experienced folks with years and years in the industry.

The backyard scientist is the one who will use polycarb because he incorrectly thinks it is right product for the wrong application.

I'm guessing your science background trumps the experience of port and hatch makers/manufacturers, who actually have to warranty this stuff, and folks who have worked or been in the industry for many, many years and who have recommended the proper sealants and the proper product. I don't think I'd call Adkins & Hoyle or Tony D'andria of Select Plastics a "backyard scientist".

Go for it, use Lexan.

Ok...ok...pull in your fangs. No reason to become insulting. I'm an Engineer and Toolmaker of 30 years. While I do not doubt their knowledge, they also state positive facts for Polycarb. And I have usually replace it on prior boats after 4 or 5 years because it scratches easily and is easy and cheap to replace. The original first post asked about sealant for Lexan and I answered accordingly. If you read the debate of Acrylic vs. Polycarb, from an earlier thread, you will see plenty of self help people with little knowledge stating all kinds of crazy so called facts. That is what I was referring to about the backyard scientists. So get off the soap box...we need the wood for our boats!!!

[Maine Sail]

Originally Posted by Celestialsailor

If you read the debate of Acrylic vs. Polycarb, from an earlier thread, you will see plenty of self help people with little knowledge stating all kinds of crazy so called facts. That is what I was referring to about the backyard scientists.

Fangs pulled in. For the many of us who did not read the previous thread making references to a thread some of us may not have read can illicit a response like I posted. I never read the previous thread, and perhaps others reading this may have not either, so I wrongly thought you were calling the professionals in this thread "backyard scientists"..

You understand the weak points of polycarbonate and also understand the strengths yet don't mind replacing it ever 4-5 years. Short replacement intervals is something many boaters would not be happy about..

[Celestialsailor]

Yes...I first got into the whole Polycarb thing because I had a Bomar hatch. They have the cast aluminum cross bars on their unit. I'm sure the reason for this was as stated...the Polycarb has a lot of elasticity and one could find a leg dangling into the galley easily. So every 4-5 years I would cut,route and glue a $25 piece of Polycarb into a $600 hatch.

[Benjamaphone]

I can't speak to what material was used in your Bomar hatch, but bars going across doesn't necessarily mean its extruded material. We carry a hatch with bars and we use 1/4" acrylic. Granted we hardly ever sell them, but if you don't need to walk on the hatch it works perfectly fine. The savings from bars to no bars with thicker acrylic might be $200-$400 depending on the size.

What dimensions is your hatch that you replace with polycarb? If its around 20"x20" then you can find a good piece cast acrylic for around $200. It should last at least 15-20 years, is less prone to leaking and breaking, and performs better in the marine environment. I can understand the savings that you report, but the process of refurbishing the hatch three to four times as often as cast acrylic does require a certain amount of time and effort.

[thinwater]

My Stiletto had polycarbonate aft and acrylic forward. I got replace the polycarbonate hatches every 7 years. The acrylic is at 30 years and going strong. Same owner, same sun, I am sure.

[mrybas]

Originally Posted by mobetah

George,
I would use a good silicone glazing caulk like Dow Corning® 999-A Silicone Building & Glazing Sealant

I would also use a good primer (THIS IS A MUST!) I've useed Dow 1200 red (the red will fade out in a week or so but in the meantime you are sure that you are getting a good coat on both the frame and lexan - clean and rough up both where primer and sealant will be applied). Without the primer the caulk WILL NOT stick to the aluminum. See the following site for more details:
Dow Corning 1200 Prime Coat - Dow Corning - SURFACE PREPARATION

Good luck, Bill A.

I'm about to put new cast acrylic lenses in my Bomar hatches with GE ultraglaze and would like to assure a good bond. Does anyone know where to buy a good primer, the linked place has a minimum $50 order (the primer is $30)?

[MichaelC]

So, Benjamophone, the website for Plexiglas calls the product cast acrylic. True? That stuff is pretty cheap. This stuff is available from my standard builders supply stores. I have made lots of skylights using polycarb [which gives no problems here in the PNW], but want to use the better product in building my new 32' cutter. If Plexiglas is the stuff, it is easy to find ..... great thread, everybody.

[CatGirl]

I'm replacing most of the acrylic in my Lewmar hatches. Does anyone know of a good tool to help get all the old sealant out of the aluminum grooves without scratching the frame too much?

[Mark Johnson]

Originally Posted by CatGirl

I'm replacing most of the acrylic in my Lewmar hatches. Does anyone know of a good tool to help get all the old sealant out of the aluminum grooves without scratching the frame too much?

A red hot, small, thin putty knife might do it IF you can lift the melted caulk out.. Have a torch going & put it in the flame every 30 seconds or so. When you melt the caulk, keep the blade moving. When it stops, it's cooled. Reheat it...
Mark