Results 1 to 17 of 17

Thread: A Maurice Griffith style hatch as a main hatch?

  1. #1
    Join Date
    Dec 2001
    Location
    Northern NSW Australia
    Posts
    70,693

    Default A Maurice Griffith style hatch as a main hatch?

    I'm unconvinced of my ability to build a water tight sliding hatch for the proposed cuddy on my 18 foot canoe yawl, JIM.

    So I've started thinking of other solutions. One that has come to mind is an MG style hatch.



    Pretty well as per the drawing, the hinge forward but with the washboards protruding sufficiently to do the job of the inner coaming on th left.

    Do people think it would work?
    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

  2. #2
    Join Date
    Mar 2011
    Location
    Mukilteo, WA
    Posts
    1,672

    Default Re: A Maurice Griffith style hatch as a main hatch?

    Would work ok I think, but do you have the vertical clearance? Would be a bummer to have it up and then the boom comes by and rips it off. If it lays all the way over it takes up just as much room as a sliding hatch, but can't be stepped on without damage in the open position. Keeping it open but vertical has numerous disadvantages. So it will have to be closed except when in use.

    It also seems nearly as difficult to build. Not sure I see the advantage.

    What do you mean by water tight? Like 8" of green water rushing across at high velocity? Okay, most sliding hatches will leak in that case.

    But most boats never see such an event.

  3. #3
    Join Date
    Dec 2001
    Location
    Northern NSW Australia
    Posts
    70,693

    Default Re: A Maurice Griffith style hatch as a main hatch?

    Complete immersion in case of a capsize, I think that would be the worst I'd expect.

    I see your points about the problems of leaving it open but raised high, 45 degrees should be OK.
    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

  4. #4
    Join Date
    Mar 2011
    Location
    Mukilteo, WA
    Posts
    1,672

    Default Re: A Maurice Griffith style hatch as a main hatch?

    Quote Originally Posted by PeterSibley View Post
    Complete immersion in case of a capsize, I think that would be the worst I'd expect.
    Goodness! Does JIM have positive flotation? I would be surprised if you could make that hatch water tight upside-down, especially where it meets the washboards. Probably better than a slider though. Try to keep it right side up!

  5. #5
    Join Date
    Dec 2001
    Location
    Northern NSW Australia
    Posts
    70,693

    Default Re: A Maurice Griffith style hatch as a main hatch?

    I certainly will but even a 90 degree knock down would put a lot of water against any hatch.
    Yes she has positive flotation.
    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

  6. #6
    Join Date
    May 2014
    Location
    Melbourne, Victoria, Australia
    Posts
    84

    Default Re: A Maurice Griffith style hatch as a main hatch?

    How much water would you expect to get inside through a non watertight hatch before it would compromise the flotation/recoverability of Jim? I would be considering something like a zippered canvas skin/cap over the sliding hatch, that keeps the spray and green water off the cabin top and back, but can be unzipped to allow access to a hatch, Once the hatch is underwater/upside down most water should be kept out by the internal air pressure, and the washboards will be the biggest factor in how much volume of water gets in, not the hatch top ?

  7. #7
    Join Date
    Dec 2001
    Location
    Northern NSW Australia
    Posts
    70,693

    Default Re: A Maurice Griffith style hatch as a main hatch?

    Quote Originally Posted by pelagos View Post
    How much water would you expect to get inside through a non watertight hatch before it would compromise the flotation/recoverability of Jim? I would be considering something like a zippered canvas skin/cap over the sliding hatch, that keeps the spray and green water off the cabin top and back, but can be unzipped to allow access to a hatch, Once the hatch is underwater/upside down most water should be kept out by the internal air pressure, and the washboards will be the biggest factor in how much volume of water gets in, not the hatch top ?
    That is a very good point !

    I have an arrangement a bit like this in mind, though I can't work out what type of hatch this is.
    Attached Images Attached Images
    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

  8. #8
    Join Date
    Sep 2002
    Location
    On the river, Auckland, New Zealand
    Posts
    4,470

    Default Re: A Maurice Griffith style hatch as a main hatch?

    I've built a couple of double coaming hatches, more than a couple in fact. Both lifting hatches on the foredeck and sliding hatches back at the after end of the main cabin. They work pretty well, no problems with leaking. Note that I used refrigerator door gasket on the inside upstand of the forward hatches, you can get a local fridge gasket guy to make one up that will fit.

    John Welsford
    An expert is but a beginner with experience.

  9. #9
    Join Date
    May 2014
    Location
    Melbourne, Victoria, Australia
    Posts
    84

    Default Re: A Maurice Griffith style hatch as a main hatch?

    french designer Henseval has used large alloy framed hatches, they don't look excessively difficult to get in and out of. You might want to consider just leaving out the washboards, and using only a double coaming or modern hatch for entry, either on the cabin roof, or on an angled cabin back like the trimaran (sardine run.)
    https://www.youtube.com/watch?v=sZalhhpqPnU
    http://www.voilesetvoiliers.com/chan...re-hauturiere/

  10. #10
    Join Date
    Dec 2001
    Location
    Northern NSW Australia
    Posts
    70,693

    Default Re: A Maurice Griffith style hatch as a main hatch?

    A good idea ....''leaving out the washboards'', it is a very low headroom so getting out would be simple.
    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

  11. #11
    Join Date
    Jul 2017
    Location
    Toodyay, Western Australia
    Posts
    476

    Default Re: A Maurice Griffith style hatch as a main hatch?

    My paradox has a proper hatch (like a hinged fore hatch, not a sliding hatch) which becomes completely watertight when dogged down on its foam rubber gasket. Easy to make, and easy to work out some dog down hardware. The boat has had big breakers roll right over the top of her without letting a drop in. She has also had a couple of knock downs partially submerging the hatch. From inside I could see under water through the polycarbonate dead light in the hatch, but again not a drop came in. I dog the hatch from the inside, but on Jim this could be done by having your dogs on the outside (and some inside depending on if you are inside or out). I reckon forget wash boards, they're a liability. Rather just make your hatch a bit bigger, and perhaps install at a 45 degree angle for ease of access. When open, design your hinging arrangement such that the hatch can open all the way back until it lies on the cabin roof... that way the boom can still clear even with hatch open. For foam rubber gasket get the sticky backed stuff off the roll from whitworths, Clarke rubber, or whatever place you blokes have over east. For days when you want air but perhaps it is raining, the hatch could be supported open to horizontal to form a kind of veranda, and that might give a semi sheltered place to boil the billy without the need to do that inside your sleeping area.

  12. #12
    Join Date
    Sep 2007
    Posts
    733

    Default Re: A Maurice Griffith style hatch as a main hatch?

    There are good reasons why neatly every other boat built in the last 500 years use a sliding hatch and not a hinge. When that thing comes down and hits you in the head you will truly understand why.

  13. #13
    Join Date
    Nov 2004
    Location
    Port Townsend WA
    Posts
    11,467

    Default Re: A Maurice Griffith style hatch as a main hatch?

    When I helped Larry and Lynn Pardy build their boats, I came up with an idea that worked so well on Serrafyn that Larry used it for the hatch on Talisen as well. The hatches have a weather strip groove built into the movable cover. Foam weather stripping is easy to renew when it grows old. A raised wooden lip on the hatch frame matches into the groove and compresses into the weather stripping. However, here is the trick that insures the hatch to be water tight. An angle bronze frame fits over the hatch lip and stands slightly proud of the wooden lip. This is only a thirty second of an inch but, it insures a tight seal because there is a dogging bolt at each corner of the hatch frame. The bolt fits into a treaded corner plate in the hatch. The bolt has a knurled bronze knob that is easy to reach from below. This dogs the hatch into the weather strip. No water gets past these hatches!
    Jay

  14. #14
    Join Date
    Dec 2001
    Location
    Northern NSW Australia
    Posts
    70,693

    Default Re: A Maurice Griffith style hatch as a main hatch?

    Thanks Jay, I have a few of the Pardey's books so will look and see if they contain a sketch of the above.
    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

  15. #15
    Join Date
    May 2017
    Location
    Tasmania, Australia
    Posts
    191

    Default

    A few french steel yachts use a neat dogging down hinged hatch that also slides foward out of the way.

    The NIS 23's have a similar system for the forehatch. Effectively it is a lifting hatch with the hinges on sliders. To use it you lift it slightly, then slide it aft and drop it down. You could easily do something like this witg the MG hatch. For sliders some sailtrack works, and does tube.

    Hinged hatches have the advantage that you can easily add triangular side flaps from perspex and have a simple poptop for extra headroom.

  16. #16
    Join Date
    Mar 2015
    Location
    Pukekohe, New Zealand
    Posts
    149

    Default Re: A Maurice Griffith style hatch as a main hatch?

    Peter, if you go to the trouble of making the Griffith hatch you should be able to build a proper sliding hatch.

    Could the mystery hatch on the blue boat be a pop up hatch, to give sheltered headroom for those below?

  17. #17
    Join Date
    Dec 2001
    Location
    Northern NSW Australia
    Posts
    70,693

    Default Re: A Maurice Griffith style hatch as a main hatch?

    Yes, it looks like a hinged hatch...... that was my original idea.

    Quote Originally Posted by Don MacLeod View Post
    Peter, if you go to the trouble of making the Griffith hatch you should be able to build a proper sliding hatch.

    Could the mystery hatch on the blue boat be a pop up hatch, to give sheltered headroom for those below?
    '' You ain't gonna learn what you don't want to know. ''
    Grateful Dead

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •