Hidden airbags to keep a yacht afloat in case of an emergency, like in the VDS example case.

Discussion in 'Boat Design' started by Angélique, Jul 22, 2018.

  1. Angélique
    Joined: Feb 2009
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    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    This thread is a split off of the thread: "Life Tender" as an alternative to life raft

    ( side note: there was a thread title change + moderator note in post #47 )

    Below the split off posts #17 & 18
    So I was surprised to see this feature on the Stadtship 70.

    Van De Stadt Design ---> History

    ‘‘ In 2008 the STADTSHIP 70 was created. This high performance cruising yacht with 1 ½ t removable water ballast, offers an excellent sailing performance while being a comfortable and safe passage maker. A remarkable feature of this yacht is the extensive pneumatic system for operating bow thruster, windlass, bowsprit, transom door and water pressure system. The yacht also has hidden airbags which can be used to keep this large yacht afloat in case of emergency. ’’

    Length over all 21.00 m
    Length waterline 18.60 m
    Beam 5.10 m
    Draft 2.90 m
    Displacement 29.0 t
    Ballast 9.0 t
    Sail area 230 m²

    KM Yachtbuilders ---> Stadtship 70 ---> PDF Specs (drawings on page 8 + 9 + 11)

    Length over all: 21.00 m / 68.90'
    Length waterline: 18.60 m / 61.02'
    Beam: 5.10 m / 16.73'
    Displacement: 29 ton
    Water ballast: 2 × 1500 L -
    (so 3 m³ ~ 3 tons there)
    Draught: 2.90 m / 9.51'
    Sail Area: 230 m²

    Now I'm wondering about these things...

    - 1. - What areas are to be filled with the airbags ?
    - 2. - How many m³ is to be inflated ?
    - 3. - What will the new waterline be ?
    - 4. - Is the airbag system set off automatically or by manual input ?
    - 5. - Which spaces are planned to be used by the survivors ?
    - 6. - Are those safe zone areas still dry or pumped out or drained after the airbags have inflated ?
    - 7. - Are they able to reach freshwater and food supplies plus dry warm clothes ?
    - 8. - What working communication options do they have there ?
    - 9. - Will the boat still be a bit sail able ? (maybe with a jury rig if the mast also has broken off in the emergency)
    10. - Will there even be some form of auxiliary propulsion available ?
    11. - What will the stability range of the partly flooded / partly air bagged / partly safe zoned boat be ?
    12. - Will the boat right herself after air bagging if she also has capsized in the unfortunate emergency ?
    13. - Is the system ever tested, and to what extent, or is this based on theory only ?

    Alas I'm not in the market for this boat, so rather than bothering the designer and builder with my curiosity I like to bring the topic up for discussion here . . :)
    Last edited: Jul 22, 2018
  2. waikikin
    Joined: Jan 2006
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    Location: Australia

    waikikin Senior Member

    This firm or similar had a system in Aus such as that... FloatPac supplies FloatPac Solar, FishPac, Flexitank & RainPac worldwide https://floatpac.com/ pretty sure they had an embarrassing demo where the deck popped off an Etchells or Soling- all the same still did what claimed some drawback is that inflation can trap passengers if not clear and from memory there was a case where a valise liferaft inflated within a cabin. Maybe communicate with them for some background .

    Regards from Jeff
  3. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    IMHO, Airbags make more sense on the outside, above the COG, maybe something like in a RIB.

    Angélique likes this.

  4. Angélique
    Joined: Feb 2009
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    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    Thanks Portacruise,

    In post #1 I've linked the info that I know of, and it mentions the airbags but doesn't say where they are, so it could as well be they are to be deployed on the outside.

    My initial thought for the inside came from the originating discussion on the previous thread, and it kept me wondering if VDS meant it as such, but indeed there's plenty of volume available on the outside, no one gets trapped, and a huge initial stability is guaranteed as long as airbags on both sides are sufficient and equally filled.

    Maybe when deployed it's kinda similar to the Woods Duo 10' Sail Row Dinghy

    On the linked page Richard gives many info plus pictures and drawings and videos, and also offers the download of free study plans.

    Last edited: Jul 23, 2018
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