Reverse Engineering (conversions And Modifications)

Discussion in 'Boat Design' started by viking north, Dec 25, 2010.

  1. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    To start with, it depends on the classification society's rules. There will be, for example, reserve floatation and downflooding angle.
     
  2. Scunthorp
    Joined: Dec 2010
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    Scunthorp Hull Tech

    So you have nothing useful to say. Can you identify what part of this statement is wrong? Have you done a lifeboat or conversion? I think you get your jolly’s just trying to piss people off which is kind of pathetic and sad.
     
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  3. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    VK

    I take your point. Every day I have clients all working “to a tight budget”. However, each client also has their own SOR and time frames. Thus each solution is different for each, even if each client wanted the same boat. Time frames are also an important part of the “budget” equation and the SOR is unique to each client. These dictate which way the solutions for the client end up going. So what may be an ideal solution for one, is not for another; owing to the aforementioned. Hence, being more generic is more informative for others rather than tailoring this for just Mr.X.

    For this we do need to know what type of hull, ie what is the design, since a sailing yacht type is very different from a tug, for example. Also you need to pin down the SOR….Statement of Requirements. Since the purpose of the vessel and what the needs and requirements of the vessel, dictate what the hull form ends up being. The Froude number, (speed to length ratio), has a major influence.

    So, for Mr. X, and others, to progress, you need to know what type of boat is required and what are the requirements. What is the boat going to be doing day in day out when finished…range, speed, accommodation, stores, services etc etc…all these affect the hull, the design and of course, cost.
     
  4. Scunthorp
    Joined: Dec 2010
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    Scunthorp Hull Tech

    Time to get a little light hearted...
     

    Attached Files:

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  5. Submarine Tom

    Submarine Tom Previous Member

    Now THAT is funny.

    -Tom
     
  6. pdwiley
    Joined: Jun 2008
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    Location: Hobart

    pdwiley Senior Member

    Your calculation may well be correct but the practical use of it is dubious - unless you personally are happy with a freeboard of 0.00 mm.

    PDW
     
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I've been reasonably content watching the blind lead the blind, after stating the obvious in the first portions of this thread. In spite of focus attempts by Tad and John, it seems the blind continue to do what the blind do, not see what's before them.

    Simply put, if you don't know what you want, can't afford what you have and aren't willing to accept the reasonable and/or usual paths to success, then you must prepare for your project's ultimate failure.

    To break this down (as I did in the beginning of the thread):
    then you need a well developed design brief (SOR). This literally and physically defines "what you want" and should expect from the boat.
    A well defined and disciplined budget is probably the biggest project goal you have. It's way more important then a replacement circular saw. If you can't find a way to afford or budget the project, you might as well stop before the money flows out the door. Remodel you kitchen instead.

    And lastly (again):
    Organization and preparation are the paths to success. If you can't find your sander, you'll never fair the hull. If you can't arrange a work schedule, organize tasks, setup vendors, out source work, get supplies delivered on time, etc., then consider painting the bathroom and leave the yacht building dreams to the doers of the world.

    Harsh, yep, damn right it is, welcome to the reality of yacht construction in a depressed market. I'm not trying to be a jerk, but sweet God the whine and shrill BS about, "wouldn't it be nice" and "if onlys" is sickening frankly. Again, there are those that think they can and there are those that do. Pick the one you want to be.

    A small fraction of a single percent of the population, actually build a yacht for themselves! Get a grip, it's hard, it's not cheap, it takes a lot of effort, time and tests your resolve on many levels. I personally like it this way. I strive and get better the harder it is, the more difficult it becomes. I live for this and it's what makes me happy to get up in the morning. My very first boat memory is of my dad's lifeboat conversion to a power cabin cruiser. He was WWII US Navy and he like many others, sucked up one of the surplus WWII lifeboats. It was a wooden double ender, but the stern had be mashed, so he cut it off and it had a pretty unique looking narrow plywood wineglass transom. I remember the smells of that boat, more then anything.

    It was the 1950's and everything was military surplus, the paint, the goo's, the gauges, everything. I remember painting the bottom of the boat one spring, down in Rock Hall, before the boat was launched. I was too young to remember how it was launched, but I remember the oyster dredgers coming in and off loading and my dad cussing about the boat's engine, which was a conversion too (automotive). I mention this because what I remember was a trip we took where we ran out of gas on the bay and had to spend the night, until Sudsy stopped by in the morning with a jug of fuel. This boat rolled liked a drunken gymnast. I don't remember where we where going or if we got there as planned, but I remember the thing rolled like a beast and more importantly, my new plastic sun glasses had melted. They'd been sitting on top of the engine box, but clearly now where a hardened pile of once molten polymer. I also remember being amazed the lenses hadn't melted and for a very brief moment attempted to wear the melted mess.

    My dad took a summer to convert the lifeboat into a serviceable cabin cruiser, that was more then capable of stranding us in the middle of the bay (my mother was so pleased). The transom was installed, the old 4 cylinder removed and the straight six installed, a cabin built, with bunks, primitive galley and a helm station to starboard of the cabin companionway. My dad loved that boat, my mom not so much, but we didn't keep it long, she was sold a year or two later. I guess he didn't like the motion either.
     
  8. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    John, I was forced to convert the excel files into Jpeg files and up-loaded them onto the Gallery Website. Unfortunately the Forum Website does not allow my cookies, while the Gallery does. Jeff is working on it.

    At the top of your Threads, click on Search, enter BertKu and click on images.

    Also you could look at the last threads on "Did a dream got shattered".
    Bert
     
  9. Scunthorp
    Joined: Dec 2010
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    Scunthorp Hull Tech

    I think I can do it let me give it a try...
     

    Attached Files:

  10. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi John,
    Not bad, she made probably also an error of tenfold when she did the calculation.

    I did.

    While walking on the beach, it hit me like a thunderblitz, that I made an mm,cm,dm,meter error and the result is not 99 m2 meter wet area for a 6,5 meter LWL, but 9,9 m2 Sorry for that. In anyway, one can only learn from the errors one makes.

    Bert
     
  11. Submarine Tom

    Submarine Tom Previous Member

    OMG, click on the girly, you're in for a surprise!

    -Tom
     
  12. Scunthorp
    Joined: Dec 2010
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    Location: Halifax

    Scunthorp Hull Tech

    sta·bil·i·ties
    1. The state or quality of being stable, especially:
    a. Resistance to change, deterioration, or displacement.
    b. Constancy of character or purpose; steadfastness.
    c. Reliability; dependability
    d. Big wobbly ****
     
  13. frank smith
    Joined: Oct 2009
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    frank smith Senior Member

    Adding the variable "d " produces unreliable stability calculations
     
  14. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Ok, just got back, Thanks TAD will have a look at that good info, Good stuff from everybody else, Frank welcome to the thread, Off to a movie and some New Years Socalizing, back tomorrow for chains, whips and icecream. HAPPY NEW YEAR EVERYBODY
    and in the New Year May The Luck Of The Irish Be With You, Geo.
     

  15. BATAAN
    Joined: Apr 2010
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    BATAAN Senior Member

    When the Coast Guard assesses a sailing vessel for use as a passenger boat, they do a practical stability test, usually consisting of filling 55 gal drums with water to heel it. Theory is fine, practice is better. Nat Herreshoff used models to design America's Cup defenders first, then did the calcs later.
    Happy New Year to All and let's keep thinking!!
     
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