Lets have a discussion on sealable walkway hatchs

Discussion in 'Boat Design' started by goldhunter_2, Apr 1, 2012.

  1. goldhunter_2
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    goldhunter_2 Junior Member

    Goggle searches have not been much help on this subject (maybe I am typing in the wrong thing :confused:)

    Even though only one bulkhead at 5% of the bow is required , I want to build in a few extra watertight compartments basically sectioning the yacht off in several large portions for added safety if the hull took damage in one section. The problem with this is I have to allow a walkway hatch that can be sealed in a emergency (something like a submarine has)

    I was hoping maybe some of the knowledgeable people on here could discuss commercial options to buy these type walkway hatches or maybe drawings for home made fabricated walkway hatch (particularly there framing and sealing devices)
     
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  2. michael pierzga
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    michael pierzga Senior Member

    Best to identify your boat and intended use. Do you already have water proof bulkheads ?

    Something to consider is that a full size waterproof door and hatch frame is an expensive and heavy piece of gear.

    A waterproof compartment also needs a dedicated bilge pumping system...also expensive.

    Why do you need a waterproof compartment amidships ?
     
  3. goldhunter_2
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    goldhunter_2 Junior Member

    Well I would like to hear about and see if possible all types of watertight walkway hatches just to get ideas on what may work for my application, But to answer your question this is for a new constitution 120' aluminum sailing yacht. MOST of the time I try to save every dollar possible but on rare occasions I decide certain things are wroth wide to me even if not normal.

    "Do you already have water proof bulkheads ?"
    NO but there in the plans:D, I plan to build these in as the hulls shell is assembled , it would be to much aggravation and expense to do this in a used hull at least for me. The actual bulkhead is fairly easy to build and frame as one of my transverse stations and basically to over simplify it is just another section of the hull ,,,,,,,,,,,,,,,,,,, the door or hatch in the walkway is something I have never built before and just can't get it worked out in my mind how the seals will function between two sections that's where I was hoping for some guidance.

    "A waterproof compartment also needs a dedicated bilge pumping system...also expensive."
    I already planed for that with separate pipes form each compartment to a rear bay of individual bilge pumps in one location for easy access. with all the pumps in one location and close to battery's it cuts my wiring down to save money, an a few extra pumps and some piping is not a great deal of added expense with all things considered at least in my mind.:confused:

    "Why do you need a waterproof compartment amidships ?"
    There is no requirement or law saying I have to build these extra watertight section, it is my personal choice that I want them. With that said just the fact that I plan to be in and out of heavily icy water always worries me, when I was younger I saw smaller boats sliced open like a tin can and can't get that out of my mind for some reason ..lol other local concerns are partly floating debris (boats trees etc etc) and sudden shift of cargo, hurricanes even at port they hit this area pretty hard sometimes. The theory it never hurts to be to safe has proved in the past to be one to keep in mind.




    Other then commercial sales of this type watertight walkway hatch I guess I would like to hear and see more about the sealing features and how they withstand dual-directional flooding , by that I mean for example the bulkhead hatch between the cabins and forward cargo hold either of these compartments could take damage and flood one way the water would push the hatch tighter against the seal but the other way would push it open it seem :confused: I had thought some type of a pocket door(hatch) so either way the water pressure pushed the hatch it would push against a seal:idea: .............I know someone at some time has had to make or use watertight walkway hatches I would just like to get some ideas on what works and how


    Also with a light damage or small breach of the hull you would have slow flooding BUT what if you took a major hit form say a partly floating container creating a huge breach in the hull the water would rush in much faster........... is there a standard to figure the surge psi against the bulkhead and the hatch :confused:


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  4. waikikin
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    waikikin Senior Member

  5. MikeJohns
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    MikeJohns Senior Member

    The level of complexity of design of the WT door depends on the head of water you want to design to.
    Most smaller craft can use a simple WT door cut from 6mm 6061 sheet with a FB flange around the perimeter 4 dogs and two hinges (adjustable) then a bulkead flange digs into a rubber strip just inside the door flange when it's closed and dogged.
     
  6. FAST FRED
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    FAST FRED Senior Member

    Something to consider is that a full size waterproof door and hatch frame is an expensive and heavy piece of gear.

    Had a pair built for our 33ft 90/90 by Singer Kerfott (SP?) years ago.
    As the boat is not deep very light aluminum was used to keep the weight down.

    MikeJohns has the description just right.

    The folks at S-K warned me that with a full head of water on one side the door would not leak, but would surely dent.

    Never happened (yet) but I would consider it a badge of honor to survive a flooding with only a dented door.

    Remember water tight subdivision has many costs and complications.

    Bilge pump in each compartment or switching manifold to be able to pump?

    Wiring cant just go thru a grommet in a hole in the wall.

    Escape must be provided for each compartment.

    An internal stuffing box will be needed if there is a bulkhead for the engine room , or the shaft alley will flood both compartments.

    FF
     
  7. michael pierzga
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    michael pierzga Senior Member

    A typical ocean going sailboat will have a ...

    waterproof bulkead aft extending forward of the rudder post.

    A waterproof engine room extending to one side of the hull and enclosing all thru hulls and exhaust.

    A forward waterproof bulkhead, well aft of the stem, enclosing the bow thruster and anchor locker.

    A bow crash waterproof bulkhead

    These waterproof bulkheads take up very much usable interior space and rapidly turn an 80ft sailboat into a 50ft sailboat.

    The floodable volume of these waterproof areas is calculated by the designer. Not too big, not too small...

    In addition two " sill " bulkheads to cabin sole height ,forward and aft of the mast step...an area of possible flooding when dismasted....and enclosing the speed and depth thru hulls.
     
  8. goldhunter_2
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    goldhunter_2 Junior Member

    waikikin ,
    Thanks that was prefect ! I like the 6 dog dutch door but probably take to long to seal in a emergency if it was already open but may be a good choice for my rear cargo door, The quick action lever door form just a quick look appears that it would be the simplest to build though probably the weakest in a reverse flooding situation , the 6dog quick action Handwheel door is what I think of as a standard it will take some studying of the wheel and dog system and seems the most complex along with the most inconvenient space wise but is probably the best option.

    MikeJohns,

    They are doing that as a single sheet with a combing and no framing ? how much of a sudden water surge would that handle on the weak (pushing the door direction) side of the door ?

    FAST FRED,
    I agree if I was to survive a flooding with a dented door I would be a happy person that it did its job!

    There will be no common use manifold in the bilge bay of pumps each pump will have its own bay and bilge pump.

    By wiring cost I simply meant it was more cost effective to run four ten foot strings of wire then it would be to run four 100' foot strings of wire.

    yes each watertight compartment is planed to have escape hatches located on the deck.

    Each engine compartment will be a standalone watertight area , for example if the stuff fails and floods the engine compartment it will not be able to flood the 2nd engine compartment or other sections of the yacht.

    michael pierzga ,
    my bow crash bulkhead, bow thruster, anchor locker, rudder post and thru hulls are already as you said.

    The actual proper calculation of what is "to big or to small" eludes me:confused: , like you said bulkheads can take up valuable space for that reason I have tried to place them when I already planed to have a bulkhead for other reasons and this way waste as little space as possible. Form the bow to stern I have one bulkhead at 6' , 34', 64',95' and 116' these aren't perfectly even but think there spacing is acquitted and it will work out with current bulkheads.

    The actual bulkhead construction I planed to double sheet it with a lighter 5086 alloy 0.125" thickness , in between the sheets I planed to frame out ever 16" with 1" flat-bar and filing the empty spaces with foam to help absorb some of the immediate impact psi form a major damage flooding surge of water , I planed to use knees for extra support alone the hull, deck and sole to help stiffing it up some. my beam is narrow at 28' my height form the sole up is 7' of head room and 3" for the deck/ceiling the bilge below the sole very s depending on location of bulkhead. all elec, drains or other items will have separate dedicated pipes welded in place to section off each compartment (not just wires thru a gourmet as someone else mentioned) Given my description of the construction of the bulkheads what are your opinions about it?
     
  9. michael pierzga
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    michael pierzga Senior Member

    With a 116 ft vessel you should consult a Naval architect before continuing.
     
  10. goldhunter_2
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    goldhunter_2 Junior Member

    Micheal
    It is actual a 120' vessel as mentioned above the 116' is the last salable bulkhead position.
     
  11. goldhunter_2
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    goldhunter_2 Junior Member

    waikikin,

    Thanks again I guess I had been typing in the wrong names when searching goggle before for information now I am finding lots of good info.

    For future reference of anyone asking about how the hatches sealing mechanisms actual work I just found this and it seems to have some decent information so I figured I would post a link to help future readers

    Instruction Book For Quick-Acting Doors, NAVSHIPS 316-0042, describes the single handle (wheel) US Navy water-tight door.
    http://www.hnsa.org/doc/doors/index.htm




    .
     
    Last edited: Apr 2, 2012
  12. Submarine Tom

    Submarine Tom Previous Member

    Remember: They only work when they're closed.
     
  13. goldhunter_2
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    goldhunter_2 Junior Member

    ha ha ha


    yep guess that is true
     
  14. Submarine Tom

    Submarine Tom Previous Member

    And, unfortunately, often overlooked.

    Cheers
     

  15. goldhunter_2
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    goldhunter_2 Junior Member

    guess it only takes once to learn the lesson :)


    with six compartments even if leaving one hatch open during a major damage incident with instant high volume flooding, I don't think would be fun but I still should be able to stay a float and hopeful find a beach to run aground on for making repairs.
     
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