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Thread: Deck Hatch - 1/2" Acrylic vs. 1/2" Polycarbonate

  1. #1
    Principal Partner footrope's Avatar
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    Deck Hatch - 1/2" Acrylic vs. 1/2" Polycarbonate

    Hello sailors,

    I have a couple questions about replacing the acrylic in the salon and bow hatches. I would really appreciate your opinions and maybe some practical experience and success stories (and maybe a deflection calculation). I've seen most of the postings on the boards, and there are some beautiful hatches out there, but they don't deal with the issue I am most unsure about - should I use 1/2" polycarbonate to replace the 1/2" acrylic?

    I have the Atkins & Hoyle alloy frame hatches, equivalent to today's XR200 (22" x 22") and XR300 (26" x 26") on my 1980 E38. The frames are in good shape. There are no reinforcing bars in the lids, and they use no fasteners to hold in the acrylic. The sheet just gets sealed into the lid with a 3/16" bead of sealer surrounding the properly shaped sheet. The 1/2" fits flush with the top of the lid. (www.atkinshoyle.com)

    1. Would 1/2" polycarbonate work? I am concerned that the 1/2" polycarbonate will flex too much and create leaks around the edges where the somewhat stiffer acrylic won't have that problem. We walk on them all the time, particularly the larger one, which gets the abuse of the mainsail related activities.

    2. Would a slightly thicker piece of polycarbonate 5/8" or 3/4" be the solution - beveled at the edges to match the lid?

    A little more info: I can have Atkins & Hoyle do the job with acrylic for about $1100 for the pair, including shipping. Three weeks door-door-door at least. On the other hand I can get acrylic and polyarbonate locally by the pound (I found a 28" x 48" remnant of 1/2" scratch resistant polycarb. for $150) and have a local shop do them, or try it myself.

    Side issue:
    I am thinking about getting clear, rather than a gray or bronze tint. It's cool up here most of the year and I'd like to brighten up the boat on the cold cloudy days. I would install a shade below each to keep out the occasionally unwanted sun. Clear stuff is much more readily available - and cheaper.

    Many thanks in advance for your help.
    Craig Davis & Ellen Le Vita

    1980 E38 "Pilot Project"
    Hull #20
    Seattle, WA



    "You can't run forever, but there's nothing wrong with getting a good head start"
    -- Rock and Roll Dreams Come Through, Jim Steinman

  2. #2
    Senior Moderator Loren Beach's Avatar
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    Exclamation

    This is interesting. We were aboard an E-38 with all Atkins Hoyle hatches, including one of their alloy-framed sliding companionway hatches, when we were boat hunting in '93. I do not remember the model, except that it was an early one... And we have never seen another one with those particular hatches.

    You probably already know that the Lexan (tm) polycarbonate is a LOT more vulnerable to UV damage than the acrylic. The Lexan should never break, but as you have noted could flex enough to pop out if enough force (heavy human or mass of water) lands on it. I understand that these two reasons are why hatch builders stick with acrylic. The acrylic lens will probably have an anti-scratch layer on it, FWIW.

    Please choose your adhesive carefully. Some stuff will attack these plastics and others just do not stick well enough. When we replaced the fixed port lenses on our boat we used "LifeSeal" and it is working well after over 6 years. 3M has some great adhesives that you might have to source through commercial window lens companies

    Best,
    Loren in PDX

  3. #3
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    If you search this forum on hatces there is a link in one post to www.selectplasctics.com. On their site under FAQ they discuss the very question you pose regarding acrylic vs polycarb. I am going to call them today to try and get an estimate on rebuilding my hatches (E 38-200 89') I understand you drive out the hinge pins send them the hatch and they redo the whole thing, lens, seals, handles. Does any one know which hatches I would be looking at in Lewmar? I think the main one is an Ocean Series size 70 and the fwd hatch a Size 60 but I am not sure.

  4. #4
    Principal Partner u079721's Avatar
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    Rollstop

    Ted,

    On my '89 E-38 the large hatch was a Lewmar Rollstop 70, and the forward hatch was a Lewmar Rollstop 60. They look a lot like the Oceans, but I don't believe they made the Ocean model back in '89.

    If you need to replace the hinges, to keep the hatches in the open position, you can buy the hinge kits from an outfit at 561-863-7444.
    Steve Christensen
    Twin Cities, MN
    Former Owner of Rag Doll
    1989 Ericson 38-200

  5. #5
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    Below is the response from Select Plastics on the hatch rebuilds.



    We are the only approved Lewmar re-build facility in the USA. See Lewmar’s web site.
    We use only Lewmar OEM replacement parts during the re-build process.

    The lenses are manufactured using the best and highest quality UV stabilized; cell cast acrylic available in the USA.

    We actually CNC rout the lenses at out Connecticut facility using Lewmar’s original CAD files.


    We replace the lens, upper seal, lower gasket, and handle seals. Every hatch repaired by Select carries a one year no leak warranty.


    We have all hinge kits and handle parts in stock if required.


    The price for the size 60 is 375.10 and the price for the size 70 is 453.75.


    Before trusting this job to a local glass shop please consider we do hundreds of these a month. We have been doing this repair for over 10 years. We advise and cooperate with the Lewmar factory in the UK on advanced sealing techniques and we really know about “sealing hatches”.


    Be careful with glass shops that will suggest replacing the lens with a Lexan lens because it is stronger. Do not seal the lenses with 5200.


    Good luck and thanks for considering Select Plastics.



    Tony D’Andrea

  6. #6
    Just last week I was talking to a shop that recommended using Lexan, this post was just in time to make me consider other options.

    Has anyone successfully glued down strips of teak (or anything else) to their hatches to protect them from feet, and the feet from slipping?

    Gareth
    Freyja E35 #241 1972

  7. #7
    Senior Moderator Loren Beach's Avatar
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    I have been around a lot of other boats over the years that had put down some rows of self-adhesive one-inch nonskid strips. That might be "plan c."

    Loren

  8. #8
    Principal Partner footrope's Avatar
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    Loren - I had heard about the UV sensitivity of polycarbonate (PC), and it is a point against PC. The sheet of PC that I was offered (by Laird Plastics) has a UV protective layer, in recognition of that. In some applications, with positive retention of the sheet, PC is an easy choice even with the higher cost. It just doesn't break.

    I have a similar slider over the companionway as you noted. There are reinforcing bars for that one. I haven't measured the acrylic thickness there. That replacement is a bit further down the to-do list.

    Ted - I visited the selectplastics site but didn't notice their discussion of the materials. That's a great website. I did just read Don Casey's (Hull and Deck Repair) section on lens replacement and noticed that he doesn't really offer an opinion between PC and acrylic in this application.

    Here in Seattle I have checked at the Laird Plastics showroom on Industrial Way in south Seattle. They sell PC and acrylic (and HDPE, and ...) remnants by the pound. They don't get much 1/2" acrylic, but they get lots of PC in that thickness. If I could get acrylic from them the cost would be under $100 for both pieces. (www.lairdplastics.com)

    According to the Laird expert(?) PC is easier/better to rout into shape than acrylic. I haven't confirmed that anywhere else.

    I have also checked with Clear Cut Plastics on Leary Way in Fremont (Seattle). They have reliable sources of clear PC and acrylic and regularly supply the boatyards and marine suppliers with lens material. 1/2" acrylic would cost me $150+ tax for the two pieces I need.

    So I'm leaning back towards acrylic.

    Thanks for the input.
    Craig Davis & Ellen Le Vita

    1980 E38 "Pilot Project"
    Hull #20
    Seattle, WA



    "You can't run forever, but there's nothing wrong with getting a good head start"
    -- Rock and Roll Dreams Come Through, Jim Steinman

  9. #9
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    On the select plastics site there is a tab at the top labeled FAQ, in it is a discussion of the merits of acrylic vs polycarb, see below I cut and pasted their thoughts.

    http://www.selectplastics.com/faq.htm

    Home About Us General Products Marine Products Lewmar® Hatch Repair Marine Hatch Repair Contact Us Links
    Frequently Asked Questions

    Hatches and Portlights

    My hatches are about 10 years old. They don't leak, but I can see these funny little shiny lines that seem to be floating in the plastic. Is this ok?

    Ten-year-old hatches do not necessarily need to be re-built. The shiny lines however are a source of concern. These lines are referred to as crazing and are a natural occurrence when acrylic is exposed to the harsh marine environment. The crazing lines are actually small cracks in the surface of the Acrylic. As Acrylic is extremely notch sensitive, both the manufacturers of the Acrylic sheet and Select Plastics recommend that you replace your hatch lenses as soon as possible. Until you have time to get these units re-built, do not subject the hatches to any load or sudden impact.

    My local marina purchased some Lexan polycarbonate for my hatches. I was told that this polycarbonate material was much stronger and more scratch resistant than Plexi. Can you explain why?

    First of all, both Lewmar Marine LTD and Select Plastics do not recommend the use of any type polycarbonate in deck hatches. During extensive testing of several brands of polycarbonate it has been determined that although polycarbonate is stronger than acrylic of the same thickness when installed, It degrades and yellows at such a rapid rate, that its useful service life could be half that of acrylic. Due to its high impact strength, polycarbonate is very ductal. This flexibility makes the material extremely difficult to seal in a hatch that was designed to accommodate the stiffer acrylic sheet. Scratching or abrasion is a significant problem with polycarbonate. The material in its standard grade has a much softer surface than acrylic. The slightest rub will cause a visible scratch that cannot be removed. Several of the major manufacturers of polycarbonate have introduced scratch resistant-ultra violet stable material to address these issues. It has been our experience that even with these costly and hard to find upgrades the special surface coatings tend to de-laminate due to the exposure to the elements. If you can't count on it to seal why use it? Polycarbonate also cost more than Acrylic of the same thickness. Add in the up-charge for the scratch resistant-ultra violet material and the material cost could easily be double that of Acrylic. Don't get us wrong; polycarbonate is definitely necessary and extremely useful. The U.S. Navy and United States Coast Guard even require it in certain applications on their vessels. Select Plastics just wants to provide you with the correct information so that you can make an informed decision regarding your particular vessel.

  10. #10
    Contributing Partner mark reed's Avatar
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    Thanks Ted, for contributing the information from Select Plastics. I was able to repair a couple of hatch leaks, but it sounds like I haven't been taking the crazing in the acrylic lenses seriously enough, and should plan to have them rebuilt. I'll have to figure out a way to both waterproof and secure the openings while the hatches are being rebuilt. Did Select give any indication of turnaround time?
    Mark Reed & Vicki Bugbee-Reed
    s/v Southern Cross
    E38-200 #250
    Portland, OR
    (currently lying Vuda Point, Fiji)
    sailingwithmarkandvicki.blogspot.com

  11. #11
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    Select Plastics advised:

    Price is good for the rollstop Lewmars also.

    Freight shouldn’t be more than 30 for both if you do the packaging on the outbound.

    We will repack for the freight back. I will pre pay and add the freight charge from Select to you.

    Lead time is currently about two to three weeks excluding freight. This is growing rapidly.

    Thanks Tony

  12. #12
    Principal Partner footrope's Avatar
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    Clear Acrylic - Do it myself

    I bought two square blanks of 1/2" clear acrylic at Clear Cut Plastics in Seattle. I will have to cut them to final shape. As for installation, I talked to a stressed-out yard worker doing a set of 4 acrylic replacements on ports or hatches and he was going to present a huge labor bill to the owner. He was stressed out over the possibility that they might leak and he'd have to eat the labor.

    He recommended I show him the lids before I decided to replace just the acrylic or replace the whole hatch. His concern was the condition of the lids, corrosion of the sealing surfaces and deterioration of the finish. Mine are anodized aluminum. He uses Sikaflex adhesives and said he would give me some advice on the process.

    I think I will do them myself rather than risk the yard bill or the hassle. If I fail, then my expenses are under $250, except for my time. I don't know anything about re-anodizing. There is some minor pitting on one hatch that may be a poor casting, rather than corrosion. The pitting was even present under the old sealer, where water never reached, which makes me think the casting process wasn't so great.

    Thanks for the discussion.
    Craig Davis & Ellen Le Vita

    1980 E38 "Pilot Project"
    Hull #20
    Seattle, WA



    "You can't run forever, but there's nothing wrong with getting a good head start"
    -- Rock and Roll Dreams Come Through, Jim Steinman

  13. #13
    Principal Partner footrope's Avatar
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    Postscript - 7 years later

    The forward and salon hatches were successfully re-glassed and with 1/2" clear acrylic sheet. The forward hatch is doing great. The salon hatch was also successfully re-bedded, but after 5+ years it needed to be redone. The corners are starting to leak. Keeping a sunbrella hatch cover keeps out UV and prevents leaking while I procrastinate. It doesn't leak when the sun shines. I used the SikaFlex 295 and followed the instructions.

    In the past year I re-bedded the sliding hatch with 1/4" acrylic - clear also. I used the SikaFlex products again. The slider has reinforcing bars running laterally. It was going to be a real challenge to scrape off the old sealer, which still held without leaks. I got an assortment of cheap wire wheels and used my electric drill to clean the old sealer off the frame. I found I could control the wheels and not ruin the finish. Following up with some sand paper and solvent finished the surface cleaning. Using the drill cut a few hours off the preparation.
    Craig Davis & Ellen Le Vita

    1980 E38 "Pilot Project"
    Hull #20
    Seattle, WA



    "You can't run forever, but there's nothing wrong with getting a good head start"
    -- Rock and Roll Dreams Come Through, Jim Steinman

  14. #14
    Principal Partner Christian Williams's Avatar
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    Say, why are the corners leaking? Is it the Sikaflex bond? Or is it the gasket? Any idea what went wrong?

    Cheers,
    Christian
    cw@christianwilliams.com
    "Thelonious" E32-3 Hull 604 (1985)
    Marina del Rey

  15. #15
    Principal Partner footrope's Avatar
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    The big hatch, about 26" x 26", is underfoot when messing with the mainsail. I suspect that the forward corners are leaking either because I didn't do such a great job cleaning and prepping, or the flexing from being stepped on has broken the bonds.
    Craig Davis & Ellen Le Vita

    1980 E38 "Pilot Project"
    Hull #20
    Seattle, WA



    "You can't run forever, but there's nothing wrong with getting a good head start"
    -- Rock and Roll Dreams Come Through, Jim Steinman

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