Deployable, shallow submersible observation pod for Catamaran

Discussion in 'Boat Design' started by abosely, Oct 7, 2019.

  1. abosely
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    abosely Senior Member

    Wondering if this might be feasible or not, must not be or it would have been done.
    Thinking about the feasibility of building an observation pod that could be deployed between the hulls of a Cat, in my case a Narai MK IV, it has four big beams to carry the pod.

    Would want it mounted as far forward as possible, so the nose of the pod was as close to or just past the bows.
    Pod would only go six to ten feet below the surface, would not be deployed for general sailing, just in mild conditions and at slow speed. Would be retracted or brought up on deck for normal sailing.

    Probably use water ballast to submerge ans bring to surface. Thinking of some sort of a tube for entry and exit. Of course safety would be paramount.

    Ideally would be large enough to hold two people at a time, don't know if that would make it to big or not though.

    Since it's not submerged deep, water pressure isn't an issue, like a deeper submersible would have to deal with. Build it out of composite and use flat or single curve viewing panels.

    Curious to see you guys thoughts, I mean this might be completely impractical idea. lol

    Cheers, Allen
  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    It sounds like enormous potential for things to go wrong very quickly - make a mistake with the ballasting or the method of deployment and the pod could quickly become a coffin.
    Is your Narai a charter boat where you take passengers on coastal cruises? If so, I am guessing that you want to offer this submersible as an extra that is novel and different?
    Getting insurance for it could prove to be very difficult if not impossible....
    If people want to see what is 6' - 10' below the surface, it would be much easier to put a Go-Pro camera on a very long selfie stick and let it feed to a TV monitor on deck. This will have MUCH less frictional resistance than a pod large enough to accommodate one or even two people. And you would be able to deploy it even while sailing, if desired.
    Oh, and even 10' below the water surface there is still quite a noticeable increase in pressure - you notice it when you dive down and your ears hurt because you haven't equalized the pressure in them.
  3. TANSL
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    TANSL Senior Member

    Why not a glass bottom boat, similar to many others that are already sailing the seven seas?. Let's suppose bottom and side of glass, to include some innovation.
  4. abosely
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    abosely Senior Member

    It would just be for my benefit.
    As I said, probably not practical or would have been done before, or at least commonly.

    Was one of those thoughts that came up in my head and thought I’d get some perspective about it.

    As you point out, with GoPro type cameras not much reason to do something like this.
  5. Squidly-Diddly
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    Squidly-Diddly Senior Member

    its either going to be coffin tight (including access tube) or it going to take huge force to push it under water. Water ballast isn't "real ballast" in this case. You've got the air-space minus the "crew" and the rest of the boat is gonna need to push that under. No reason to add water ballast to boat, just let pod push boat higher.

    "deploy-able" (moving parts) sounds like death-trap. Its gonna be cramp, something jams, it floods and something blocks escape.

    I think you'd be better off with plexiglass underwater windows in hull, and build to survive that section of hull flooding. That would allow frequent casual use by you and guests, as opposed to high drama death defying infrequent stunts where you'd be too worried about a disaster to view the fish. IMO any super-yacht should have underwater viewing room just aft of the bow, and maybe also aft, since I hear lots of big fish like to follow boats.
    bajansailor likes this.
  6. Tiny Turnip
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    Tiny Turnip Senior Member

    6 year old very sub (ha! see what I did there?) Go Pro on a stick dangled off my pedal cat in murky waters. Im sure you can do much better still at a fraction of the cost, danger and difficulty of a pod:
  7. abosely
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    abosely Senior Member

    I realize this isn’t a good idea.
    Just a thought and wanted to see if it might be feasible, but as has been pointed out not a good idea.

    This wasn’t a thought out idea, just something that popped into my head.
    Wanted to get some thoughts on it.
    all very good points and definitely not something I’m going to think about doing.

    Thanks for the input guys.

  8. W9GFO
    Joined: Dec 2014
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    W9GFO Senior Member

    I think you are underestimating the forces at that depth. Water pressure at ten feet is approximately 5psi. A one foot square flat panel would have to withstand over 700 lbs of force.
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