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Construction question

Discussion in 'Yacht Designers Discussion' started by moondragon, Mar 5, 2010.

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  1. moondragon

    moondragon New Member

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    Did a quick search and didn't see anything regarding this, so I thought I would ask.

    I am playing around with several large yacht designs and was wondering what the average hull thickness, bulkhead thickness, interior wall thickness's were on a yacht in the 60 - 80m range. I am doing layouts and want the drawings to reflect actual sizes, not theoretical ones. Any help would be appreciated - Thanks
  2. moondragon

    moondragon New Member

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    anyone???
  3. 'RoundTheHorn

    'RoundTheHorn Senior Member

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    Classification Societies

    You may want to check with a classifiaction society as they provide guidance for design and construction - ABS, Lloyds, DNV, etc. You can download some materials from ABS for free - not sure about the others.

    Wikipedia has a huge list with links - http://en.wikipedia.org/wiki/Classification_society
  4. Marmot

    Marmot Senior Member

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    What material?
  5. moondragon

    moondragon New Member

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    thanks for the lead. got a bit of reading to do.
  6. moondragon

    moondragon New Member

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    working on a steel hull, aluminum superstructure and an all aluminum one as well.
  7. Henning

    Henning Senior Member

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    It depends on a lot of things, not the least of which is what type of service will it see. It's not all about strength either, as material wasteage over time is also factored in. So another question is, "How long do you want it to last before you have to start replacing metal?" The thicker it is, the longer you have before the pitting becomes critical, and again, critical is factored by the intended purpose and what may have to be endured.

    There is also the question of which engineering style are you going after. Lots of ifs.

    That said, on say a 200' yacht with a steel hull, I would expect to see no less than 3/8" or 10mm on the bottom. In Aluminium for a displacement hull I would expect no less than 9/16" or 14mm. Those are limited duty figures. In a "go anywhere" vessel, I would expect triple those. High speed aluminium yachts will be different, and they'll go for a compromise in alloys (you can't "T" 508x aluminium alloys) to gain the required strengths from less mass and use engineered extrusions for the extra stiffening.
  8. moondragon

    moondragon New Member

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    Henning, thank you for the reply, that definitely helps, what about overall thickness's?? 18" outer hull??? 12" bulkheads??? interior non load walls??? This will be a displacement yacht, go anywhere, maybe 12 - 16 knots cruise.
  9. Henning

    Henning Senior Member

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    In the hull, why would you ever design a non-load wall? Even if it's minimal it should provide something. If you're talking closet partitions and such, whatever you feel they should be, though I recommend every division be a fire barrier.

    Somebody gave you the correct answer already, look in the classification society's standards and guidance for the one you are going to build to. From my experiences with this vessel, I have lost all respect for a Lloyds certificate. In my careers experience ABS is pretty much the strictest with DNV being a fair mid ground. Their standards are rigorous, but they'll work with you. I've only worked with BV once and that was a very simple straightforward deal.

    Whatever society it is you deal with, you'll need access to the full set of codes. As for the straight forward engineering stuff, all the societies are pretty much on the same page, you can use any of them for basic planning , costing and design purposes before you send it off to the engineers. If/when you get serious, Autoship and like programs have costing and other features as well as design software. For boats this big you have the power to place mill orders and get whatever different materials you want at a "per ton" price, you can even order special alloys designed specifically for your needs for a nominal surcharge. Cost out the entire material of the project and infrastructure cost, everything up to the owner taking delivery, and multiply by 4. That's going to give you a fair ballpark of what it's going to cost all up to deliver the boat. Multiply that by 2 and it gives you the retail asking price.

    Me, for 200' I'd be 5/8 bottom plates to the inner chine, 1/2" to the outer chine and up to 12" above the waterline, 3/8 for the next width of plate and 5/16 from there up. For the house I wouldn't use metal at all, lightweight cored composite, or cold mold wood.
  10. moondragon

    moondragon New Member

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    thanks henning, i have been reading the pdf's in the above link. Some heavy duty mathmatics to absorb!!!!