I always like the 19th-century look of rivets on a ship hull. I understand that rivets are pretty labor-intensive, and are not the best way to join two plates (the stress concentrates at the rivet points). So when did welding displace the rivets?
Also, in battleships, i’ve heard there were several instances of shells striking a rivet head, which has then driven into the ships 9causing damage)-did this really happen?
I know that in WWII ships were being welded, but that’s as far back as I know. I suspect it was an inter-war development.
As for rivet heads being turned into projectiles, that could happen too. Sometimes, it would just be a piece of the ships structure. When a piece of thick armor takes a big hit, it can knock off a chunk of armor on the inside of the ship. This is called spalling. This is a problem for tank crews as well. Some tanks have “spall nets” lining the crew compartments to help prevent and reduce the damage from spalls. WWI tank crews actually wore protective goggles and chainmail face guards because of the tiny little spalls created by rifle and machine guns hitting the armor around their firing ports.
It was a gradual process that began in the 1930’s.
From http://www.welding.com/history_of_welding2.shtml#8
“Stud welding was developed in 1930 at the New York Navy Yard, specifically for attaching wood decking over a metal surface. Stud welding became popular in the shipbuilding and construction industries.”
Welding in lieu of riveting became the common practice during World War II, when the speed with which a ship could be safely and properly constructed became a prime concern. We were effectively having to replace our Navy while in the midst of war, and the speed with which we could build every ship counted. I don’t have good cites to provide on this, but I believe you’ll find some stuff on the decision in looking up Secretary of the Navy Frank Knox or Fleet Admiral Ernest J. King.
The development of shielded arc welding electrodes by A.O. Smith Company in the early 'Thirties was paramount to being able to weld large steel structures without cracking and corrosion problems from inclusions due to atmospheric combination of nitrogen and oxygen in the weld bead. The United States had effectively stopped all shipbuilding until the mid-to-late Thirties when it was clear that we’d need to provide transAtlantic logistical support first to Britian and latter for our own forces, and that new techniques and processes in welding would be superior to riveted construction. Here is an article from Time Magazine’s archives on welding in WWII-era shipbuilding, and here is an extensive article from GlobalSecurity.org on WWII shipbuilding.
Rivets are also good in shear (although improperly designed rivet joints can display problems with stress concentrations) but not so wonderful in tension and require large lapping joints which add weight and complexity. A good, well designed welded joint (which does require more skill but less labor than welding) will stand up to shear and tension equally well. See Omer Blodgett’s Design of Weldments or Design of Welded Structures for technical details on designing good welded structures and joints.
Stranger
It wasn’t quite that easy. Didn’t some of the Liberty ships have problems with cracking of the welds in cold Arctic waters?
Riveting a ship was pretty risky work, too - handling the hot rivets and hammering both sides.
I seem to recall that when the SS Great Eastern was disassembled, the bodies of a couple of riveters were found in the hull :eek:
Si
Yes, but the benefits of welding far outweighed such matters (mind you, many of the ships literally broke apart when the welds cracked).
Modern shipbuilding was basically pioneered in WWII by Kaiser shipyards. They came up with the idea of modular construction for shipbuilding. (This had been used at one point in time in building wooden ships, but had fallen out of fashion when metal ships came about.)
Interestingly enough, welding wasn’t the only thing to come out of WWII shipyards. Employer provided health insurance (Kaiser Permamente was started by Kaiser to reduce employee absenteesm during the war.) Kaiser also convinced Howard Hughes to build the Spruce Goose. And the profits Kaiser made during the war funded his abortive entry into the automotive field.
The weld metal and associated heat affected zone adjacent to the weld have different mechanical properties than the parent metal itself; some contaminants or processes can exacerbate this. Welding is frankly a big pain in the ass, and it takes a much more skilled worker to weld pieces together than to bolt or rivet them. But in the end, welding almost invaribly gives the best permanent joint for materials amenible to welding.
And oddly enough, Kaiser had esssentially no experience in shipbuilding prior to the buildup for WWII; Kaiser’s main business was freeway construction and public works projects.
Modular construction was used, in part, because of the problems of welding in overhead positions. Whereas riveting can be done in pretty much any orientation, it’s difficult to get a good bead when the weld material tends to flow out of the joint, so it was easier to attempt to modularize parts that could be moved and rotated into an ideal weld position. This led to other advances in inspection and tolerancing (since the parts had to all fit together with minimal adjustment) and probably had a lot to do with the success and reputed high build quality of post-war assembly line manufacturing, particularly in the automotive industry.
Stranger
I’ve heard of stuff like this, but had always dismissed it as UL - is there any truth to it?
According to wikipedia - probably.
I would guess that they probably fell, rather than got sealed in - at least I would like to think that.
Si
Thanks for that. I’d heard a version where a worker fell down into a deep void between outer and inner hull (or between two bulkheads or something) and could not be rescued without significantly destroying part of the ship - even though he was alive and his cries for help could be heard - so they gave up and carried on working - and he could be heard banging on the hull for several days.
-Which of course has plenty of UL features, but the story you cited doesn’t sound nearly so implausible.
I think it would be unlikely that someone trapped inside the hull would not be rescued in Victorian times, and (as noted) inspection hatches make being trapped unlikely. But once people were working, you certainly could not make a signal that others would hear. More likely someone fell and died (or maybe was murdered and hidden).
Otherwise, it was a sacrifice to Posiden 
(where are you putting the body on your boat, mangetout? - or is it a pound coin under a bulkhead)
Si
There’s not much room on my boat to hide a body, although a fresh one might make a comfy seat. Interesting you mention the pound coin, because I was already wondering if there was any kind of tradition regarding hiding a coin in the construction - I found a silver sixpence on the beach a couple of weeks ago and thought back then that I might build it into the boat.
A coin under the mast was the usual trick.
Maybe put it under the seat.
Si
I’ve heard about the “missing riveters” sealed in the hull of the Great Eastern. Pretty good ghost story–it’s said they kept banging on the hull…
Wikipedia has a good account of that amazing but somewhat unlucky ship. Including the rumors, of course! Similar tales were told of other ships.
I know that SDMB is fact based. But rumors & legends are fascinating–as rumors & legends.