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  1. #1
    Join Date
    Aug 2006
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    Perth, Western Australia.
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    87

    Default Installing inspection hatches - fixings

    When/if you install an inspection hatch, how do you fix it in place?

    The common or garden screw-in variety comes complete with a set of holes ready to take a set of screws or bolts. Both times I've installed the things I've thrown away the holes and replaced them with an epoxy glue, not being able to think of any reason to remove said hatch in the future.

    Was I wrong? What did you do?

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  3. #2
    Join Date
    May 2009
    Location
    Hobart
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    106

    Default

    If you glued them in with epoxy are you happy that the epoxy has bonded OK to the plastic?

    Epoxy doesn't bond to plastics, at least not in my experience.

    I have always used screws and a bead of sealant to make sure they don't leak.

    Cheers, Cameron

  4. #3
    Join Date
    Aug 2006
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    Perth, Western Australia.
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    Default

    Good point. To date they stay in place and don't come out however hard I tug at them. If I fully flood the boat and weigh it down to keep underwater they remain water-tight. So far...

    What did you use as a sealant? I gather MIK abhores Sikaflex.

  5. #4
    Join Date
    Jun 2007
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    Aberfoyle Park SA
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    Default

    I think silicone sealants are the issue, not Sika the brand.

    Non-silicone sealants, including those made by Sika have their uses.
    I used Fixtech MSP Clear polymer to glue in my hatches. No screws.
    Like you, I can't imagine ever needing to remove them. Very happy with it.
    PAR recommends polysulphide sealants for a bunch of things.
    A thread search will turn up much useful data.

    cheers
    AJ

  6. #5
    Join Date
    Jul 2010
    Location
    Finland
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    Default

    I have use sikaflex 291 and 292 - not screws.

    With 291 I think the hatch could be removed and used again?

    Perttu

  7. #6
    Join Date
    Apr 2009
    Location
    Melbourne, Australia
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    Default

    I also used SS screws & sikaflex 291. Bought a whole tube of the goop and used a fraction of it... It's now in the fridge waiting to be confused with something edible

    I wanted a mechanical fastening because I'd clear-finished the bulkhead before I installed the hatch, & I didn't trust an adhesive to fix to the finish and the hatch.

    Of course, now I'm worried that the screws have created a vector for water to get into the ply, especially as they were self tapping (can't goop epoxy into the hole first) and the ply is so thin (possible blow-out on the back of the ply).

    (Geez, now I'm getting nervous. Maybe I should get inside the hatch with some epoxy and recoat the back of the bulkhead....)

    I surfed the web for a while looking for instructions, and the 291 & screws was generally what I found. I'd be interested to hear what the pros on this forum say, (as long as it isn't that I should strip the whole shebang out and do it again...)

    Jack

  8. #7
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    Jun 2007
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    Default

    Back the screws out & use a syringe to soak the holes in the ply with epoxy.
    When thoroughly soaked, put a wee drop of WD40 on the screws & reinsert.
    How big are your hatches ?
    AJ

  9. #8
    Join Date
    Apr 2009
    Location
    Melbourne, Australia
    Posts
    45

    Default

    Mine are the 150mm inside diameter white screw-hatches. Good for getting an arm in to feel for water...
    Good idea about the syringe, too. I'll give that a go.

  10. #9
    Join Date
    Jul 2005
    Location
    'Delaide, Australia
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    65
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    Howdy - yes - I don't like silicon sealer, but I like sikaflex and others!

    Originally with my raceboats I screwed and used sealant. Then I realised during the yearly varnish process (before the days of epoxy) that I could take the screws out and still couldn't get the hatches off.

    So I started just using the sealant. I've done that for years without the tiniest problem

    However, there is a dark side.

    When I went on the Kokopelli Cruise - the canoeing trip on the Lake Powell section of the Colorado River - we were using kayaks that had been built by Chuck at Duckworks.

    http://www.flickr.com/photos/boatmik...7622510542194/





    Similarly he had found out that you just don't need screws.

    However during the trip, for some reason, the inspection ports on one of the kayaks started popping off and we didn't have any screws to fix it!!! So I would trust the sealant without screws for normal use, but if taking some risks, I would think about screws.

    Or maybe just glue on the hatch and then have a serious try to rip it off the bulkhead or deck!

    MIK

  11. #10
    Join Date
    Oct 2007
    Location
    Poland
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    Default

    I've installed inspection hatches using acrilic Soudal FIX ALL (no silicone) and 6 (no 12) tiny brass screws :



    Last edited by robhosailor; 10th April 2011 at 08:21 PM. Reason: added another photo and info
    Aloha!
    Robert Hoffman
    http://robhosailor.blogspot.com/


  12. #11
    Join Date
    Aug 2006
    Location
    Perth, Western Australia.
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    Default

    Hi Rob,

    What were you screwing into? Just 4-6mm plywood? Or is there additional backing?

  13. #12
    Join Date
    Oct 2007
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    Quote Originally Posted by MichaelB View Post
    What were you screwing into? Just 4-6mm plywood? Or is there additional backing?
    Just 6 mm plywood - no additional backing. Screws really tiny (short) are.
    Aloha!
    Robert Hoffman
    http://robhosailor.blogspot.com/


  14. #13
    Join Date
    Jul 2005
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    'Delaide, Australia
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    Default

    Quote Originally Posted by Boatmik View Post
    Similarly he had found out that you just don't need screws.

    However during the trip, for some reason, the inspection ports on one of the kayaks started popping off and we didn't have any screws to fix it!!! So I would trust the sealant without screws for normal use, but if taking some risks, I would think about screws.

    Or maybe just glue on the hatch and then have a serious try to rip it off the bulkhead or deck!

    MIK
    If it don't come off easy - you don't need the screws!

    MIK

  15. #14
    Join Date
    Apr 2009
    Location
    Hunter Valley NSW
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    Default

    I did the opposite, no sealant, just screws into the 6mm ply. I think if you use sealant, a 1mm hole drilled through the hatch will help blow off the pressure or release a vacuum after launching into cold water on a hot day.

  16. #15
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    Screws into the 6mm ply is fine. I think if you use sealant, a 1mm hole drilled through the hatch will help blow off the pressure or release a vacuum after launching into cold water on a hot day.

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