Inflatable Airbag System to Improve Ship's Attained Subdivision Index

Discussion in 'Boat Design' started by Devu De Goa, Oct 30, 2016.

  1. Devu De Goa
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    Devu De Goa Junior Member

    Dear Sirs,

    A paper by me titled "Inflatable Airbag System to Improve Ship's Attained Subdivision Index" will be presented at the #SMC2016 Maritime Convention of the Society of Naval Architects and Marine Engineers at Bellevue Washington on 04th Nov 2016.

    As part of the process, I am taking feedback/comments regarding the paper from everyone. These discussions will be shared with SNAME for sharing with the people who are present at the convention to have a meaningful discussion.

    You are requested to kindly go through the paper and provide your comments:
    https://www.researchgate.net/public..._to_Improve_Ship's_Attained_Subdivision_Index

    Best Regards,
    Devu
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

    I think the most obvious flaw is that it is an inflatable air-filled bag. Not permitted, since if it is damaged/leaks/punctured, said buoyancy is lost.

    One can only achieve with solid foam type, which is hygrospic.
     
  3. Barry
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    Barry Senior Member

    No mention of the issues of the air bags going off and trapping passengers within rooms or hallways. Then if you limit the air bags to places that people will not require a path of egress, then you may not get enough buoyancy to float the boat
     
  4. Devu De Goa
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    Devu De Goa Junior Member

    Sir, the suggested materials are with good anti puncture qualities. More research is required on that front.
     
  5. Devu De Goa
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    Devu De Goa Junior Member

    Sir, the design of ships has to evolve to accommodate both. There is scope for that with advances in materials and computer technology.
     
  6. jehardiman
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    jehardiman Senior Member

    The naivete of that paragraph is just priceless.

    http://dilbert.com/strip/2016-09-06
     
  7. Devu De Goa
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    Devu De Goa Junior Member

    The references cited have focused on that instrumentation, probably over a century ago. :)
     
  8. jehardiman
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    jehardiman Senior Member

    I take it you have never investigated the cost, space, weight, and maintenance required for a self-activating HP or LP air de-watering system that has to work, each_and_every_time, in a man-safe system.

    How much and how fast are you going to need to dewater?

    Lets say a nominal cruise liner is ~60,000 to 70,000 tons displacement. Lets say a max draft of 33 ft just to keep the math simple and divided into 10 compartments. So each compartment, at a permeability of 0.7, needs ~318,500 scf to dewater.

    So to dewater in 6 minutes for LP you will need multiple (for redundancy) ~2,000 kW blowers driven by emergency diesels. For HP (say 200 bar) each compartment needs flasks with a volume of 1593 cf or ~ 450 tons for the ship. And that has to be DRY AIR or you will freeze the system up. And then there the whole class certification issue, and the need to fit HP compressors and air dryers.

    Yes, the idea and systems have been around for a while, so there are very good reasons you don't see any deployed. Not to burst your bubble, but a shell puncture leaves ragged edges. And we haven't even broached the subject of how to design for survivability of the system given the damage penetration requirements.
     
  9. Devu De Goa
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    Devu De Goa Junior Member

    There are two types of proposed deployment. Void spaces for example can have airbags which need not wait till an actual damage situation to get inflated. It is only in the tanks like ballast tanks that you would think of inflating / deflating system, but if the ships can survive ballasting of those tanks, why do they need the system? Does that solve half of the problem?

    Also, to begin with, we need to focus on more manageable sizes of ships, not 70000 tonners. For example, we don't think of deploying waterjets for propulsion of Very Large Crude Carriers. Technology of water jets is not useless if it can not be used for VLCCs. :)
     
  10. jehardiman
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    jehardiman Senior Member

    Have the already inflated balloons in void/ballast tanks only? What if the void/ballast tank is damaged? Also, why protect ships with 35 people (VLCCs) on board rather than those with 5000 people on board (cruise liners). You really need to do a full and complete concept development on this. Look at where the most good for the least effort/cost resides.
     
  11. Devu De Goa
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    Devu De Goa Junior Member

    Yes Sir. I intend to take up further work on the subject may be as part of my Masters thesis. Can you suggest any companies that might be interested in this work?

    Also regarding the VLCCs, I think the problem of environmental damage is also critical. I would like to asses the most important applications of this product. Say for example, this can be very critical for some defense products or luxury yachts where people are willing to pay for additional safety.

    Would be glad to get some feedback on that as well.
     
  12. Squidly-Diddly
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    Squidly-Diddly Senior Member

    I'm all for it.

    I'd be afraid of going over 5 miles from a Coast Guard heli-rescue station in an keelboat without SOME chance at positive flotation.

    I dismiss all this talk about "has to work anytime, everytime".

    To me, its just one of a system of safety plans to improve your odds.

    Nothing works "all the time, everytime" including PDFs, body armor, airbags, vaccines, alarms, etc.

    For starters, in any keelboat, I'd want airbags installed in all the non-emergency areas (everywhere except the helm/radio/nav up in the nooks and crannies so they wouldn't block egress. They would scream when wet and auto inflate, with instant deflate rip cords.

    I knew a guy who finished out a nice hull, took on a few shakedown sails up and down the SF bay and it seemed all good. Next weekend he takes it out, returns to spend the night aboard. 3am he wakes up to a flooding boat settling into the marina mud.

    Helicopters carry insta-flate bags on their struts, and helicopters are about 10x as weight critical as any boat.

    How about a ring of Reactive Inflatable Fenders around a boat's hull. Like Reactive armor on tanks, but different. Any hit from the side beyond someone's boat shoe shoving and it inflates to protect both hulls from damage. Could also be manually inflated en mass in emergency to turn whole boat into a sort of RIB. About 2' long sausages about 3" around that would turn into 2'x2'x2' rounded squares.

    Further, it would be trivial to make a system where instead of one big bag, its maybe 20 little bags inflating inside a big bag. You'd need 4 accurate shotgun blasts to defeat most of it, and their would still be enough for a PDF/marker buoy.

    You might even have Closed Cell instant foam, similar to Polycell foam used in house insulation. Even as the boat is sinking it would adhere to wet surfaces and provide flotation. One hella of a mess to be sure, but thats what Insurance is for.
     

  13. Devu De Goa
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    Devu De Goa Junior Member

    Thank you Sir for those comments. I am sending this discussion with whatever commenst are received till now to SNAME so that they can include in tomorrow's discussion.

    Thank you everyone.
     
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