Which rule?

Discussion in 'Class Societies' started by Mat-C, Jul 11, 2010.

  1. Mat-C
    Joined: May 2007
    Posts: 255
    Likes: 12, Points: 0, Legacy Rep: 141
    Location: Australia

    Mat-C Senior Member

    Simple question...;)
    25 foot, aluminium planing hull, for recreational use.
    Which scantling rule / method is best?
     
  2. Paul Kotzebue

    Paul Kotzebue Previous Member

    ISO 12215-5
    Small craft ― Hull construction and scantlings
    Part 5: Design pressures for monohulls, design stresses,
    scantlings determination
     
  3. Willallison
    Joined: Oct 2001
    Posts: 3,590
    Likes: 130, Points: 0, Legacy Rep: 2369
    Location: Australia

    Willallison Senior Member

    It depends a fair bit on what you're trying to achieve Mat. ISO is probably the most widely used now, though ABS (and the Oz standards which are based on ABS) are also widely accepted.
    If you're after a simple, easy to follow, conservative rule the Gerr's Elements of Boat Strength is fine too.
     
  4. Mat-C
    Joined: May 2007
    Posts: 255
    Likes: 12, Points: 0, Legacy Rep: 141
    Location: Australia

    Mat-C Senior Member

    Thanks Paul, Will.
    Paul, why do you suggest ISO over others - ABS, Lloyds etc?

    Will, I'm just trying to establish which method gives a good strong structure at the minimum weight
     
  5. Alik
    Joined: Jul 2003
    Posts: 2,851
    Likes: 201, Points: 73, Legacy Rep: 1306
    Location: Thailand

    Alik Senior Member

    Mat, ISO12215-5 has simplified method of scantlings calculations suitable for boats with LH<9m. I am sure in Your case it is the way to go.
     
  6. Paul Kotzebue

    Paul Kotzebue Previous Member

    Lloyd's Special Service Craft is applicable for yachts over 24m. ABS guide for motor pleasure vessels is applicable only for yachts over 24m. I don't think ABS or Lloyd's has current scantling guidelines applicable to recreational motor craft under 24m.

    ISO 12215-5 is applicable for recreational craft between 2.5m and 24m. The ISO simplified method is fine if the boat falls in design category C or D.
     
  7. Mat-C
    Joined: May 2007
    Posts: 255
    Likes: 12, Points: 0, Legacy Rep: 141
    Location: Australia

    Mat-C Senior Member

    Great - thanks.
    Now, Can I just buy ISO12215-5, or do I need the whole damn lot....? I mean, I know I can buy just part 5, but will it enable me to do all the calcs without having the other standards to refer to?
     
  8. TeddyDiver
    Joined: Dec 2007
    Posts: 2,578
    Likes: 120, Points: 73, Legacy Rep: 1650
    Location: Finland/Norway

    TeddyDiver Gollywobbler

  9. Alik
    Joined: Jul 2003
    Posts: 2,851
    Likes: 201, Points: 73, Legacy Rep: 1306
    Location: Thailand

    Alik Senior Member

    Paul, we did 15m pleasure cat to LR SSC rules. They work quite good for small craft below 24m.

    Teddy, for craft below 12m compliance to ISO12215-5 is not mandatory.
     
  10. rxcomposite
    Joined: Jan 2005
    Posts: 2,092
    Likes: 226, Points: 63, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    Special Service craft

    Paul,

    LR is applicable for yachts UP TO (150 ft?) All other types (cat,mono,patrol) is for below 24 meters. Anything above 24 meters is ship and LR has a different set of books for that. THe minimum scantlings of LR becomes impractical for small boats but the calculation procedure is bulletproof.

    I agree ABS is for 24 meter above. They dont touch anything below 24 m.

    ISO is more applicable for small boats.


    Regards,

    RX
     
    Last edited: Jul 12, 2010
  11. Willallison
    Joined: Oct 2001
    Posts: 3,590
    Likes: 130, Points: 0, Legacy Rep: 2369
    Location: Australia

    Willallison Senior Member

    ABS High Speed Craft:

     
  12. Paul Kotzebue

    Paul Kotzebue Previous Member

    ABS High Speed Craft is not applicable to recreational vessels.

    This is from LRSSC:

    2.1.1 The Rules are applicable to the following craft types
    constructed from steel, aluminium alloy, composite materials
    or combinations of these materials:
    (a) High speed craft.
    (b) Light displacement craft.
    (c) Multi-hull craft.
    (d) Yachts of overall length, LOA, 24 m or greater.
    (e) Craft with draught to depth ratio less than or equal to 0,55.

    So, for recreational vessels (yachts), LRSSC is only applicable if LOA is 24 m or greater. I am not aware of an upper length limit in LRSSC.

    Scantling guidelines can be used outside their intended scope as long as the user understands the limitations. However, the answer to the original post is ISO 12215-5.
     
  13. Alik
    Joined: Jul 2003
    Posts: 2,851
    Likes: 201, Points: 73, Legacy Rep: 1306
    Location: Thailand

    Alik Senior Member

    I believe that the only reason why LR SSC rules exclude 'yachts' below 24m from classification is LR's policy. They just don't want to touch this type of boats, pushing them towards harmonised European ISO12215-5. Generally ISO results heavier/stronger hulls compared with LR SSC.
     
  14. Paul Kotzebue

    Paul Kotzebue Previous Member

    That seems reasonable to me as well.
     

  15. rxcomposite
    Joined: Jan 2005
    Posts: 2,092
    Likes: 226, Points: 63, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    I may be wrong Paul, I do not have the LR special rules with me at the moment. I am living on a suitcase.

    What I do remember is the number divides a yachts and a megayachts.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.