Hatch cover build

Discussion in 'Fiberglass and Composite Boat Building' started by midnitmike, Sep 27, 2012.

  1. midnitmike
    Joined: Apr 2012
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    Location: Haines and Juneau

    midnitmike Senior Member

    I was recently asked to build a set of hatch covers, and thought it would be a nice idea to take a few pics along the way. Because there are a number of pictures detailing the steps in this build I'm going to use thumbnails of them instead of the larger shots so they don't slow down reading of the thread.

    1) I start out with a flat lay up table that uses a 3/4' melamine surface for my mold.

    2) Painters tape is used to protect the table surface and to make clean-up easier.

    3) The first two coaming pieces are hot glued in place establishing a square corner. These two coaming will be used for all three hatch covers, so they're well braced with a few extra tabs.

    4) Next I'll use this pre cut coaming piece to secure and align the longer section as I hot glue it in place.

    5) All four coaming are now in position on a flat and level surface.

    6) I'll wax all the surfaces with what I think is the best mold release wax money can buy...Johnsons Floor Wax! It goes on easy...buffs out in seconds, and never seems to fail when it comes time to demold your part.
     

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  2. midnitmike
    Joined: Apr 2012
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    Location: Haines and Juneau

    midnitmike Senior Member

    Part 2

    6) For this project I decided to try using Freemans 1/2" wax radius material.

    It was not an easy solution and I think the learning curve was a bit too steep. Eventually I came up with a workable solution and a viable radius, so I went ahead with the build.

    7) Next comes a nice even coat of PVA sprayed on using a small touch-up gun with a 1.0 nozzle. This by far the smallest gun I've ever used for spraying PVA, but I was amazed at how much PVA it delivered and how well it worked. There is no doubt in my mind this is going to be my favorite gun for all of my future PVA work.

    8) Gelcoat is then sprayed into the mold and allowed to cure for at least three hours.

    9) Once the gelcoat has tacked off a 3/4 oz matte is applied for the skin coat and allowed to fully cure.

    10) Since this is going to a foam cored hatch I'll precut and dry fit the interior layup and the foam core.

    11) Once that's kicked off I can finish laying up the hatches inside coating. Make sure you use enough resin to allow for any run out into the core below.
     

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  3. midnitmike
    Joined: Apr 2012
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    Location: Haines and Juneau

    midnitmike Senior Member

    Part 3

    Once the hatch cover is demolded and trimmed I like fitting them to the coaming on the boat, just to make sure everything is going to work like it's supposed to. If you have an defects in the exterior surface or the radius now's the time to fix them.

    12) A portion of the top was taped off and gelcoat and non-skid applied.

    There must be a dozen ways to do this. My procedure is to roll out a layer of gelcoat, sprinkle a bit of non-skid onto the surface, and then roll on a bit more gelcoat to even out the grit and give it a nice even look. I normally use a lint free roller and discard it afterwards.

    13) I have to run out to the shop and take a picture of the finished hatch cover.

    And there you have it.

    MM
     

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  4. garrybull
    Joined: Nov 2010
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    Location: portsmouth england

    garrybull Senior Member

    thats exactly the same way as i make all my hatch covers.

    i also make a gutter moulding that the cover fits too.

    the gutter allows any rain water etc to drain through a skin fitting and out the side or rear of the boat.

    i've still got to hinge them and fit catches yet but you get the idea.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  5. swade
    Joined: Jun 2010
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    Location: apollo beach,fl

    swade Senior Member

    Thanks for the nice writeup. Sorry these are going to be very newbie questions but i had to reply as I was googling this topic some months ago. Read it described in bunch places but it's nice to see pics here.

    i made a hatch with a quick 1 off mold like this. since it was a 1 off I just wood glued everything with a few finish nails, but said i would do it more like this next time.

    Only I didn't gelcoat the mold, i decided to just spray afterwards and sand it out and polish. That's mainly because i'm comfortable spraying after the fact and have never shot gelcoat yet in a mold. Are you guys using a dump gun or regular spray gun?

    Just hot glue and corner tabs braces everything well enough? You put painters tape just under the wood frame strips right? Not over the entire melamine?

    those gutters are nice, doubt i'll ever make one but I was wondering how people did those. I assume you frame your hatch, then go back and frame your inner pocket?
     
  6. midnitmike
    Joined: Apr 2012
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    Location: Haines and Juneau

    midnitmike Senior Member

    I'm sure there's more then one way to skin this cat when it comes to building a one off mold set. In my case I have three hatch covers to make and each of them are of slightly different measurements. That means I need to be able to easily deconstruct and re-use the first mold in order to make the next two. That's one of the reasons you see so much painters tape, on the table, and on the coaming stock edges. The hot glue is applied to the taped surfaces, and not directly onto the melamine. That way I can peel off the tape instead of having to scrape off the hot glue itself. Tape is also applied to the upper exposed edges of the melamine coaming pieces. This serves to keep gelcoat and resin from penetrating into the more porous edge sections. And yes using just tape and hot glue it's plenty tough enough. Of course you want to be careful how you handle your mold. My table is on rollers, so I can if need be, move it outside the door to spray and then back inside next to the heater to aid in the curing. This done very gently so as to not disturb the wax radius more then anything else.

    Applying the gelcoat to interior of the mold serves two purposes, one it helps eliminate the pin holes you get with just a straight matte layup, and two it serves as my base coat for future gelcoat surfaces that I'll be applying. I doubt I'll ever get a perfect exterior finish on one of my hatches...it seems like there's always going to be a mishapened corner, radius, or pre release some where. I've just gotten used to the idea that I'll be sanding the exterior surface, fixing any minor imperfections, and applying a couple layers of gelcoat before it's done.

    I've got an old ES dump gun, but no cups, so I use modified HVLP guns or modified texture spraying guns to spray my gelcoat.

    MM
     
  7. garrybull
    Joined: Nov 2010
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    Location: portsmouth england

    garrybull Senior Member

    i brushed gelled my moulds. quick and easy.

    the gutters were made from bits timber and then filled and sanded smooth and then i applied a few coats of duratec primer and then flatten and polished them up[ a bit and then made the gutters.

    really simple to make.

    i got the hatch lids flowcoated today and gritted with deck flowcoat mixed with dried sand which i find really grippy.

    just got to fit the hinges and lift handles and there finished.

    [​IMG]

    [​IMG]

    [​IMG]
     
  8. garrybull
    Joined: Nov 2010
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    Location: portsmouth england

    garrybull Senior Member

    heres a couple pics of my gutter moulds before i flattened them off and polished them up.

    [​IMG]

    [​IMG]
     
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  9. Agl marine
    Joined: Sep 2012
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    Location: Malta

    Agl marine AGL

    Very nice

    Always nice to excellent craftsmanship.
     
  10. swade
    Joined: Jun 2010
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    Location: apollo beach,fl

    swade Senior Member

    Very nice! Thanks for the additional info and pics.
     
  11. midnitmike
    Joined: Apr 2012
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    Location: Haines and Juneau

    midnitmike Senior Member

    I really like the idea of using a gutter mold, it certainly makes for a nice flush deck arrangement. I have to admit that I get the chills just thinking about laying that piece up...eight radii all within a few inches of each other.....brrrr.

    MM
     
  12. garrybull
    Joined: Nov 2010
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    Location: portsmouth england

    garrybull Senior Member

    its easy to lay up.

    once 2 coats of gel are on the radius gets a little bigger so the mat go's on quite easy.

    I've got the hatches fitted now and the deck completely gel gritted. will post some pics when I'm back home from work on friday.
     
  13. garrybull
    Joined: Nov 2010
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    Location: portsmouth england

    garrybull Senior Member

    heres the pics of the hatches all fitted and the deck gel gritted over. just got the lift handles to fit.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  14. midnitmike
    Joined: Apr 2012
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    Location: Haines and Juneau

    midnitmike Senior Member

    How about unwrapping that center console and posting a few pics of it as well.

    MM
     

  15. garrybull
    Joined: Nov 2010
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    Location: portsmouth england

    garrybull Senior Member

    no probs mate.

    its not a centre console. its a walk around wheelhouse just big enough to get 2 people in out the weather.

    i like a lot of deck space on my boats and the small wheelhouse suits it perfectly.

    you can see more pics in the projects section below

    link http://www.boatdesign.net/forums/projects-proposals/fairey-hunt-18-a-42011.html

    heres some pics for you

    [​IMG]

    [​IMG]

    [​IMG]
     
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