Hull Construction/Scatling Rules for Multihull Aluminum

Discussion in 'Boat Design' started by bateaudemoi, Jun 30, 2020 at 2:57 PM.

  1. bateaudemoi
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    bateaudemoi Junior Member

    Could anyone point me in the right direction on where to find rules for scantling calculations for an aluminum catamaran? Concept is a 15m houseboat!

    Thanks in advance
     
  2. gonzo
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    gonzo Senior Member

    "The Elements of Boat Strength" by Dave Gerr is a good source.
     
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  3. TANSL
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    TANSL Senior Member

    The regulations of the Classification Societies are the most complete to calculate the scantlings of a boat. The Lloyd`s Register "Special Services Crafts" Regulations are very good for all those floating artifacts that are boat-like. For boats smaller than 24 m in length, ISO 12215 is specially designed for them. The problem is that the standard for catamarans has not been published yet, but the monohull standard can be used, with some modification and performing some calculations, such as transverse beams between hulls, by direct calculation.
    I do not believe that any official body of any country accepted calculations made through the "The Elements of Boat Strength". That in the event that an official body must supervise and approve your calculations.
     
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  4. bateaudemoi
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    bateaudemoi Junior Member

  5. TANSL
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    TANSL Senior Member

    You are welcome. Do you need some help with this issue?. I'd help you with pleasure.
     
  6. Ad Hoc
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    Ad Hoc Naval Architect

    There are no Class "rules" per se, for house boats that you are seeking.

    Firstly you'll need to establish is the house boat going to be motorised, in the sense of, will you be able to move location from one berth/harbour to another.
    Then that will lead you into variations of "possible" rules you could use.... but in the first instance most Class rules start at 24m length. You can of course use the Class rules for vessels below 24m, but the results may not be palatable - in the sense of thickness being more than you want or expect. However, one assumes that weight of structure will not be a major issue?

    Would you be doing the classifications yourself, or will you be seeking assistance from "another"?

    You may try using DNV-GL rules, these are easy and simple to follow, HERE. Ignore the "house boat", as this is not a Class notation, just assume a passenger catamaran.

    Or, as already noted, you may use LR's SSC rules, which are not so easy to follow for a beginner as there are many cross references and constants to calculate, but provides and equably suitable alternative.

    Good luck ...
     
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  7. Alik
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    Alik Senior Member

    DNV-GL has standard 0342. I recommend to use that standard as it is specifically designed for craft under 24m.

    The DNV-GL HSLC rules are too much oriented towards larger ferries, also their design loads are known to not to work for small craft. This is not just my opinion, this recommendation from DNV-GL office in Hamburg.
     
  8. Alik
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    Alik Senior Member

    Fully concur. The book is practical for amateur boatbuilders building heavy displacement monohull craft. But not for engineering of structures which should be certified, and not for multihulls.
     
  9. Ad Hoc
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    Ad Hoc Naval Architect

    I did consider that, but it is linked to the EU directive rules for compliance which are a total nightmare for anyone not familiar with the EU directive rules.
    And since the OP is in Canada, I don't consider them it to be applicable, since ostensibly the OP is just after structural rules, only.

    We've been telling them that since 1991 :D ... when the original "Golden Rules" came out ... they were ostensibly aimed at the bigger INCAT boats that started to flood the market. and smaller vessels were penalised for it.
     
  10. Alik
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    Alik Senior Member

    Actually they are not linked to EU rules. This DNVGL 0342 standard is for non-recreational craft.
     
  11. Ad Hoc
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    Ad Hoc Naval Architect

    That's why the rules are a mess to navigate as they are tenuously linked, and it gets very foggy what DNV-GL consider to be applicable or not.
    Not helped when it states in their own scope that it's both:-

    upload_2020-7-1_16-15-20.png

    Just a mixed bag at best... :confused::oops:o_O

    Thus if the Op just needs a set of rules for establish a basic structure, against "some" measure of compliance, just use the rules linked above.
     
  12. gonzo
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    gonzo Senior Member

    Canada is like the USA for recreational and six pack boats. They need to meet safety and other regulations only; not structural design.
     
  13. TANSL
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    TANSL Senior Member

    Are you sure?
    Is not safety a well designed and well calculated structure?
     
  14. SamSam
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    SamSam Senior Member

    The last I looked into it, the boat construction was not important for 6 pack regulations (with possible limitations on where you could go), they were concerned with life jackets, fire extinguishers and that sort of safety fittings.

    CONSTRUCTION REQUIREMENTS [33 CFR 181 and 183; 46 CFR 25 and 45]

    [ ] [ ] [ ] Hull Identification Number (HIN) [Vessel constructed after 1 AUG 84].

    [ ] [ ] [ ] Certification [vessels less than 20 feet]: Safe Loading. Safe powering. Level flotation.

    [ ] [ ] [ ] Certification [inboard gasoline power]: Fuel and electrical systems.

    [ ] [ ] [ ] Ventilation [all vessels using gasoline as fuel]. 46 CFR 25.40 or 33 CFR 183.601

    [ ] [ ] [ ] Coast Guard/UL/SAE Approved backfire flame arrester on all gasoline engines (except outboards).

    [ ] [ ] [ ] Cooking, heating and lighting systems must be approved. 46 CFR 25.45

    [ ] [ ] [ ] Start in gear protection. [Outboards after 1 AUG 82]. 33 CFR 183.70.

    http://wow.uscgaux.info/Uploads_wowII/054-08-01/6PackCheckList.pdf

    .
     

  15. TANSL
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    TANSL Senior Member

    @SamSam, it seems frankly incredible to me but as you are the one who affirms it, who usually speaks only of what you know, I will make an effort to believe it. However, I very much doubt that anyone cares about the structure of a 15-meter floating device (house boat as per the OP) that, in addition, will transport, will have accommodations, for various passengers. What else, very important for other types of ships, is it not necessary to take care when designing ships for the USA or Canada?
     
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