Stability of the Bounty Replica

Discussion in 'Stability' started by Earl Boebert, Feb 20, 2013.

  1. Earl Boebert
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    Earl Boebert Senior Member

    Most of you are probably familiar with the sinking of the HMS Bounty replica in Hurricane Sandy. The Coast Guard inquiry is underway now, and there is one question that nobody seems to have asked. The emphasis is entirely on structural issues, leaving open the question of the design.

    Reasoning from analogy with the original vessel doesn't seem fruitful because the replica, originally built as a movie set, was oversize in some dimensions. It seems to me that an analysis similar to that which the collective skill of this forum performed on the Costa Concordia would be a valuable addition to the historical record. Such an analysis is beyond my abilities, but if I were capable of performing it I would consider the vessel as originally built, as modified with external ballast, and in its partially flooded state prior to capsize.

    Any takers?

    Cheers,

    Earl
     
  2. gonzo
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    gonzo Senior Member

    The key is that is was a movie set and not a proper boat. It was not a replica, but something that looked alike enough to make a movie.
     
  3. HakimKlunker
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    HakimKlunker Andreas der Juengere

    The ORIGINAL Bounty is my all time favourite!
    My take:
    Both ships sailed for many years and sufficiently reliable.
    That does not have to mean that they were perfect, of course.
    For modern (and traditional) ships we have tools and knowledge to do things right - engineering, design, handling,...(?)
    So, if we already know how to do it right, there is (in my eyes) not much sense in inspecting the wrong things; this is how Giovanni does it and it leads into dead ends.
    As you say: that replica was made for making a movie and not so much with an idea of making it perfect. It was as it was. Let her rest in peace and honour - and the two casualties as well (!)
    The sinking - to my understanding - was because of technological failures and not so much because of dimensioning details.
    That leads to a somewhat nautisophical question:
    'Is it correct to re-make a (ca.) 250 year old ship and add an engine, battery power, electronics, etc? - and expect that it performs better?'
     
  4. Earl Boebert
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    Earl Boebert Senior Member

    Well, that's one (common) assertion. Another (also common) assertion is that it was a proper tall ship. Both assertions are backed up, AFAIK, by nothing more than anecdotal evidence and expert opinion. On the one hand, it capsized with such violence it flung the crew overboard. On the other hand, it sailed for years, crossed the Pacific to Tahiti and crossed the Atlantic.

    It seems to me that there are people on this forum who have both the skills and tools to determine that it was a seaworthy design, it wasn't a seaworthy design, or we can't tell. As Sherlock Holmes famously said, "It is a capital mistake to theorize before one has data." It wasn't a particularly complex vessel, and I continue to think that an analysis by disinterested parties would be a valuable contribution to the historical record. After all, somebody may decide to build another one.

    Cheers,

    Earl
     
  5. Tad
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    Tad Boat Designer

    She capsized suddenly because she was half (or perhaps more) full of water. The captain and crew apparently did not recognize the danger in staying aboard a vessel with stability so reduced.

    Lack of stability did not sink the Bounty. She sank because she filled with water.
     
  6. Number4

    Number4 Previous Member

    http://gcaptain.com/bounty-hearings-chief-mates-testifies/

    Testimony today including a number of things far more concerning than a two-minute dissonance between the mate and the captain. Svendsen testified about alterations to the ship’s construction arrangement in the yard period just prior to sailing that including the moving of fuel tanks and the addition of other tanks, new hatches, new tonnage openings and ladders, and all of it without Coast Guard or class oversight. The ship routinely sailed – according to Svendsen’s comments on Coast Guard evidence – with sails not in Bounty’s approved sail plan and carried removable ballast forbidden by the ship’s stability letter. Caulking on the ship’s plank seams and the replacement of planking raised eyebrows as well. But without access to all the evidence, it was hard to draw conclusions about what Svendsen was commenting on. There was a picture that none in the gallery could see and a reference to DAP and the number 33. Did the crew that caulked the seams of Bounty in the yards prior to sailing use house-grade DAP sealant on the planking seams? I don’t know. It seems more likely that they were bottom coating with Interlux 33 – but these are facts that were alluded to, not verified.

    One rumor confirmed by Svendsen was that Bounty routinely needed bilge pumping in normal conditions. “We had to run the pumps once or twice during every four-hour watch.” Bounty made water – lots of it. During his last watch on the morning of October 28th – less than 24 hours before she went down – Svendsen said, ” the bilge pumps were running constantly.” Perhaps he attributed that to the sea state and water coming down from the weather decks, but he hit the rack just after noon thinking the ship was in good shape. Six hours later he was convinced that the ship was taking water through the planking at two spots on the port side (according to his testimony today). Six hours after that, he was alone in the Atlantic and swimming for his life.

    After Svendsen’s testimony was finished, Carroll and the panel discussed a piece of evidence (CG-12) – a 2010 survey report from the American Bureau of Shipping – that outlined 19 deficiencies requiring attention if Bounty was to be issued a Load Line certificate. The issues ranged from weather-tight fittings and missing hatch gaskets to improper drainage and problems with watertight bulkheads. The Coast Guard investigator kept repeating the phrase “that repair was not done” when referring to an interview with the ship’s owner following the sinking. The load line certificate was never issued.
     
  7. Submarine Tom

    Submarine Tom Previous Member


    I believe they're called "reproductions".
     
  8. Earl Boebert
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    Earl Boebert Senior Member

    Of course. But how much water did it take before her stability was compromised below reasonable levels? Nobody knows. She leaked chronically, and knowing these parameters would give an indication of how much she was at risk during previous voyages.

    Cheers,

    Earl
     
  9. Earl Boebert
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    Earl Boebert Senior Member

    I believe several witnesses confirmed the use of household grade DAP as caulk for cost reasons.

    Cheers,

    Earl
     
  10. Tad
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    Tad Boat Designer

    From Michael Mason, a Nova Scotia Naval Architect......From the WoodenBoat thread on this same subject......



    " And let's just stop this foolishness about "she was just a flimsy movie set". Yes, she was built for the production of "Mutiny on the Bounty", but the changes to the original design were designed by an experienced, well-known naval architect, built by shipwrights with enormous amounts of experience in building large wooden ships, and built to class to the rules of the American Bureau of Shipping. The metal brackets so frequently mentioned here are a common method of adding strength to a structure and were happily employed in designs by Herreshoff, Alden, and others. As designed and built, she was expected to sail half-way around the globe, and you don't expect that to be done in a cobbled-together set-dressing. The structural problems of the Bounty were due to age and under-funded maintenance, a problem that most traditionally-built large wooden vessels suffer after fifty years of almost continuous use. These weaknesses were brought to a fatal prominence by taking the vessel out into weather that should - and could - have been avoided. "
     
  11. Tad
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    Tad Boat Designer

    Well, if her captain had a current stability booklet and the knowledge to use it, he could easily caculate the point (damaged stability plus free surface) when things got really dangerous.

    But there had been numerous changes in ballast, tankage, and openings. Couple that with no current Inclining data, no hull lines, and no solid data on flooding.......there's little to base any stability study on even if there was a point to it.
     
  12. peter radclyffe
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    peter radclyffe Senior Member

    i dont know if dap is the same as european glazing putty, it may be, and it has been approved by lloyds and others for 100 years for seams, as well as seam compound,it is one standard mixed with red lead to kill everything and sometimes grease as it is flexible , however it may be irrelevant for the time period from the yard to sinking, as it is the caulking, oakum or cotton which makes the seams watertight, not the compound, which is to protect the caulking ,
    to illustrate that, although its not good practice, there is a 15 mt dive boat here which has not used seam compound ,putty or anything over the oakum for 20 years, he,s too mean, but it still is watertight, he gets away with it because the planking is eki,azobe and worm resistant
     
  13. Earl Boebert
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    Earl Boebert Senior Member

    Anybody know who the designer was?

    Cheers,

    Earl
     
  14. gonzo
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    gonzo Senior Member

    I saw the boat in Tampa years ago and knew several volunteers that worked in the "at the dock" display. It was patchwork of wood, screws, plywood, sheet metal and anything else that was cheap and would keep it floating at the dock. As far as I know it was never properly repaired. In fact, since it was built as a movie set, it was not as structurally sound as a proper ship would've been.
     

  15. Tad
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    Tad Boat Designer

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