trimaran stability booklet

Discussion in 'Stability' started by bazza, Oct 30, 2007.

  1. bazza
    Joined: Oct 2005
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: british virgin islands

    bazza Junior Member

    I have to complete a MCA stability information booklet for multi hull sailing vessels for my charter trimaran. Does anyone know if this can be done by a NA without them actually seeing the boat. ( we are in the BVI and I don't think there are any here). In the MCA jargon they require the "side hulls" to be at least capable of 150% of the buoyant volume. Does anyone know the exact definition and measurement points for the "side hulls" Does this include everything outside of the main hulls lines IE the ama and cabin area between main hull and ama. Or is it ama up to the line, where if it was filled with water ,the water would start to run over the bridge deck floor and start to fill the main hull or what. If the booklet can be compiled from data from measurements taken from the boat and sent to a NA is anyone interested in a job.
    thanks Bazza.
  2. gwboats
    Joined: Sep 2005
    Posts: 108
    Likes: 8, Points: 28, Legacy Rep: 77
    Location: UK

    gwboats Naval Architect

    Trimaran Stability Book

    There should be no problem providing a 'long range' stability book if your trimaran is under 24 metres long and you are confident to carry out a simple stability (inclining) test.

    Over 24 metres you will need to have the Stability test observed by a surveyor approved by the MCA.

    The accuracy of the results in the Stability Book depend completely on the care with which the test is done but I can send you a procedure if you need it.

    Other information needed will be accurate, dimensioned drawings of the hull, deck, superstructure and rig.

    I have no record of a requirement for side hull buoyancy alone. My MCA regs. require reserve buoyancy to be 25% of displacement to ensure the tri remains afloat after a capsize. Maybe you could send me the reference you have.

    Needless to say you will have guessed that I am offering my services as a Naval Architect!
    I frequently prepare Stability Books to MCA standards and have good links with MCA head office as we are both based in Southampton UK.

    Contact me off forum if need any further information.

    Good Luck
  3. bazza
    Joined: Oct 2005
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: british virgin islands

    bazza Junior Member

    Thanks gw. I am not at home for a couple of weeks so I will check into whats needed and get back to you. Its 20 meter designed by nigel irens in 79. As far as confident about an incline test I have a photo of her in over 20 knots and in need of a reef with 10 guests sitting on the leeward bow and the anti foul is only under a couple of inches (worst case scenario.)The boat has operated here since 79 without incident and now all of a sudden they want a stability test. The rig will come down way before she flew a hull!
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