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Post by privatepaddy on Dec 20, 2012 16:38:03 GMT
Personally I think that modern vessels capsize and sink upside down because watertight compartments and heavy steel upper works.
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Post by the light works on Dec 20, 2012 16:49:20 GMT
you mean turtle and remain afloat upside down? yes, that is a logical conclusion. modern sealed bouyancy systems are specifically designed to prevent sinking, and modern broad beamed vessels, depend on righting moment and the fact they don't have to fight sail loading to prevent capsizing; so they have less ballast. many modern large day sailing vessels (I.E. 20-30 foot range) are designed to be self righting, but motor vessels are not necessarily self righting.
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Post by privatepaddy on Dec 20, 2012 16:53:47 GMT
you mean turtle and remain afloat upside down? yes, that is a logical conclusion. modern sealed bouyancy systems are specifically designed to prevent sinking, and modern broad beamed vessels, depend on righting moment and the fact they don't have to fight sail loading to prevent capsizing; so they have less ballast. many modern large day sailing vessels (I.E. 20-30 foot range) are designed to be self righting, but motor vessels are not necessarily self righting. Modern warships gun turrets will fall off they say to change the centre of gravity and help the ship right itself.
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Post by the light works on Dec 20, 2012 16:56:28 GMT
you mean turtle and remain afloat upside down? yes, that is a logical conclusion. modern sealed bouyancy systems are specifically designed to prevent sinking, and modern broad beamed vessels, depend on righting moment and the fact they don't have to fight sail loading to prevent capsizing; so they have less ballast. many modern large day sailing vessels (I.E. 20-30 foot range) are designed to be self righting, but motor vessels are not necessarily self righting. Modern warships gun turrets will fall off they say to change the centre of gravity and help the ship right itself. they also say it is because the turret is so heavy that with the ship in normal trim, holddowns would be redundant, and with the ship out of normal trim, the holddowns would be ineffective.
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Post by privatepaddy on Dec 20, 2012 17:00:42 GMT
Modern warships gun turrets will fall off they say to change the centre of gravity and help the ship right itself. they also say it is because the turret is so heavy that with the ship in normal trim, holddowns would be redundant, and with the ship out of normal trim, the holddowns would be ineffective. This may be true, I do not remember a case where a ship righted itself minus its turrets but I am not exactly an naval historian.
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Post by Cybermortis on Dec 23, 2012 14:34:47 GMT
Personally I think that modern vessels capsize and sink upside down because watertight compartments and heavy steel upper works. Modern ships are less likely to capsize than old sailing ships, as the former have a MUCH lower centre of gravity and higher overall mass. This is why far more people get sea-sick on sailing ships (which roll more) than on a modern ferry*. Of course it took a while to get the figures right, and at least one British pre-dreadnought warship rolled over and sank due to the weight of the turrets - something that had been predicted would happen, and it should be noted occurred during bad weather. Like sailing ships any modern ship so unstable to be easy to roll over is likely to do so when launched or when she firsts puts to sea. (*For comparison, the MS Liverpool Seaways ferry displaces just under 22,000 tons. HMS Victory masses some 4,500 tons and the USS Constitution around 2,200 tons.)
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Post by the light works on Dec 23, 2012 14:46:19 GMT
I believe unless the ship is designed to be rolled over, the rolling process does enough damage that even if it self rights, it is at risk of swamping (though sealed bouyancy at least keeps it at the surface.)
I am currently reading a book on Coast guard stories, and it refers to one small boat skipper who smoked cigars. one of his crew told the author you could tell what the ride would be like by what happened with the cigar. if he spit it out, you'd better take a deep breath because you are going to be upside down for a while.
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Post by privatepaddy on Dec 24, 2012 3:43:54 GMT
Personally I think that modern vessels capsize and sink upside down because watertight compartments and heavy steel upper works. Modern ships are less likely to capsize than old sailing ships, as the former have a MUCH lower centre of gravity and higher overall mass. This is why far more people get sea-sick on sailing ships (which roll more) than on a modern ferry*. Of course it took a while to get the figures right, and at least one British pre-dreadnought warship rolled over and sank due to the weight of the turrets - something that had been predicted would happen, and it should be noted occurred during bad weather. Like sailing ships any modern ship so unstable to be easy to roll over is likely to do so when launched or when she firsts puts to sea. (*For comparison, the MS Liverpool Seaways ferry displaces just under 22,000 tons. HMS Victory masses some 4,500 tons and the USS Constitution around 2,200 tons.) I have had the pleasure of visiting HMS Victory twice in 2004 and in the bicentenary year of Trafalgar. The second visit was far more interesting as visitors were allowed to walk around at their pleasure not as part of a group tour. If we take "capsize" as being its dictionary definition and the one I grew up with that a ship/vessel is inverted IE keel up. It would take a special set of circumstances to achieve this condition in the subject of this thread. The pirate vessel would have to broach in high winds and heavy seas. Is this part of the myth? During training I was told that one inch of water across the surface of a compartments deck was sufficient to destabilise a vessel depending on the size of the compartment it could lead to putting the vessel in extreme peril. Personally I would like to see this put to the test and see if it is possible to capsize a pirate vessel of this era. My interpretation would be the vessel would in normal seas and winds go to the point where the masts and rigging are on the waters surface preventing further rotation at which point the hull floods with water via the hatches and sinks first dragging the masts and rigging after it.
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Post by the light works on Dec 24, 2012 14:40:53 GMT
I think taking a ship with bare masts and attempting to capsize it by action of the crew and cargo would be a reasonable proof of concept. - taking, as you said, "capsize" to mean past the point of loss of righting moment; or with a model, you could build it with sealed bouyancy and attempt to actually turtle it.
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Post by privatepaddy on Dec 24, 2012 14:51:29 GMT
I think taking a ship with bare masts and attempting to capsize it by action of the crew and cargo would be a reasonable proof of concept. - taking, as you said, "capsize" to mean past the point of loss of righting moment; or with a model, you could build it with sealed bouyancy and attempt to actually turtle it. put simply I do not agree at all that bare masts is an acceptable scenario. Few Pirate ships of that era sailed with out spars, sails and rigging.
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Post by the light works on Dec 24, 2012 15:27:24 GMT
very well, bare masts, spars, standing rigging, and tackle. few pirate ships of that era found themselves totally becalmed in a magical place where they had to turtle the ship at sunset in order to get back to the real world, either. "Bare Poles - the condition of a sailing vessel when she has no sail set" from www.photographers1.com/Sailing/NauticalTerms&Nomenclature.html#B
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Post by privatepaddy on Dec 24, 2012 15:34:01 GMT
very well, bare masts, spars, standing rigging, and tackle. few pirate ships of that era found themselves totally becalmed in a magical place where they had to turtle the ship at sunset in order to get back to the real world, either. "Bare Poles - the condition of a sailing vessel when she has no sail set" from www.photographers1.com/Sailing/NauticalTerms&Nomenclature.html#BSo the myth lays in the world of magic anything is possible in that place. ships sailing along without sails people with octopus faces even
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Post by Cybermortis on Dec 24, 2012 16:41:38 GMT
very well, bare masts, spars, standing rigging, and tackle. few pirate ships of that era found themselves totally becalmed in a magical place where they had to turtle the ship at sunset in order to get back to the real world, either. "Bare Poles - the condition of a sailing vessel when she has no sail set" from www.photographers1.com/Sailing/NauticalTerms&Nomenclature.html#BThis is inconsistent with the scene in the film. The Pearl has every sail* hanging limp from the yards. Doing this test on a real sailing ship - or a wooden three masted sailing ship - would be impractical due to cost, even a small amount of damage would cost a fortune to repair. It would also be FAR too dangerous as before such a ship rolled over the top-gallant masts and yards would snap the braces/shrouds holding them on place which would risk anyone on deck being hit by several tons of wooden pole. Hence the use of a scale model. They could always run a limited test on one of the reproductions sitting in San Diego. A plum-line hanging from the taffrail with a coloured board behind it would show the amount of roll the ship had. However such a test naturally couldn't be carried out to the tipping point, and the Captain of the ship in question would have to be there to call a stop to testing if he feels there is any risk to the masts and rigging at any point. (In other words, it wouldn't be very dramatic and might not produce footage they could use). (*Interestingly this includes jibs and stay sails, which would have been almost unheard of on civilian ships circa 1800. I'd assume that since the people who helped set up the rigging for the Black Pearl were experts such sails were in use in the early 1700's - I'm unsure when they started being used myself. It would also be reasonable to assume that Pirates, who tended to alter their ships as much as they could to make them faster, would have made use of such sails if they were in use.)
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Post by the light works on Dec 24, 2012 17:17:32 GMT
however, if you were making a complete miniature, then not adding sails would reduce the amount of work necessary, and if you were making a model that used real people as the crew analog, omitting the sails would reduce risk of entanglement - AND you would have less camera obstruction. and those of us with sailing experience know that it is no myth that wind in the sails can knock a boat over. so by eliminating the sails, you focus on the balance issue. (and reduce the drag, which makes it easier for the boat to rock)
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Post by Cybermortis on Dec 24, 2012 18:54:19 GMT
The balance will be affected by the sails, as they add additional weight well above the water line. Besides, in order to test the scene you have to recreate it as accurately as possible - so that means sails in place. Sails themselves would not pose any significant problem, as unlike the main rigging they would not need to be attached or secured in an historically accurate manner - unlike the stays and braces.
Creating a scale model that a human would be capable of standing in for the entire crew of some 30 pirates would be totally impractical. By my rough and ready calculations you'd need a ship some 40 feet long. My notations about how to test on a real sailing ship was intended to highlight a potential test that could be tested on, say, 'HMS' Surprise down in San Diego. Not how they would run tests on a model.
Eliminating wind and wave action was already taken into account in my ideas regarding testing - specifically to run the tests indoors in a pool. The size of model I was talking about (some 8-10 feet long and 2-3 feet wide) would be small enough to fit into an indoor pool without complications. Such a 'rig' has a number of advantages, from not having to worry about damage, through the small size being easy to build* and that it could be reset to test out variables on site.
(*In terms of build it wouldn't be much more complex than the 'houses' they have been building for years - and would be around the same size. The internal framing would need to be a lot heavier and stronger, but the build itself doesn't have to conform to 'historically accurate' ship-building methods from the period. What is being tested is stability, which will rest with the shape of the hull and the distribution of weight. Fine tuning might take a while, but I'm guessing that once they have drawn up deck plans it shouldn't take more than a day or so to build - and the deck plans are something MB can get hold of and modify easily in pre-production.)
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Post by the light works on Dec 25, 2012 3:09:20 GMT
I'm thinking they want it to be much more durable in the hold.
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Post by silverdragon on Dec 26, 2012 8:26:26 GMT
I think that is the general consensus Cyber.... if you flip a ship, its going to Davy Jones eventually....
If not, wouldnt there be a number of "Turtle" hulls accounted for somewhere in History?... Mostly history has the exact words you used (above) "Sank" somewhere in the account.....
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Post by silverdragon on Dec 26, 2012 8:36:28 GMT
Side note....
In History, I spent a merry day trying to turn a boat over.
27ft long RIB type craft, that we needed to test the self-righting mechanism.... This thing was built to survive being dropped off 50ft waves... it was built to set the original around-the-cost record of Britain.... and almost un-sinkable... we say almost, we did not suggest it would survive a head-on at full thrutch into a Lighthouse for instance?...
Two hours on full thrust playing in the waves hitting them as sideways as we can?.. not happening.... the thing was THAT stable... huge fun, but we wanted it upside down?...
Eventually we got dockside, borrowed a crane, ran straps under the hull and craned it upside down....
20 seconds later it was back the right way up.
So, it is possible that you CAN "Turtle" a ship, but not one of those older ones....
May I also suggest that if upside down, you wont be having Masts or Sails?.... Surely the force of water hitting them are going to rip them off as they smash through?....
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Post by privatepaddy on Dec 27, 2012 2:09:49 GMT
Regarding the myth perhaps if we regard any wooden spar touching and entering the water as breaking the "spell" that holds the Black Pearl in Davy Jones Locker?
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Post by blazerrose on Dec 28, 2012 7:29:03 GMT
Moved here from the Bounty thread in the Water Cooler:
Posted by the light works on Yesterday at 6:26pm Re: Flipping a Pirate Ship - Pirates of the Caribb I think for a real boat test, if the ship's master lets you get a gunport within a foot of the water, we'll have to settle for that. if it's a purpose built model, well, then passing the point of no return is really the only standard that should apply.
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