There’s some funny comments on here! But the truth is it’s a lot easier to weld the hull plates with it upside down so it’s a common practice. Though the flipping is usually done on land, I’ve never seen it done in the water before.
Actually, the USS Merrimack was a wooden frigate with auxiliary steam power. Burned to the waterline during the evacuation of Norfolk Navy Yard in the opening days of the war, she was later rebuilt as a casemate ironclad and rechristened CSS Virginia.
Up to a certain size, it's much easier to build a boat hull upside-down. You can lay the flat deck on a shop floor, or on simple supports, and build up from there, with no need for expensive, custom framing, and with minimal need for overhead welding. Ask anybody who's built their own boat, and they'll probably tell you they did it upside-down.
Borderline Alcoholic They realised it was built upside down after they launched it and the people trying to build the wheel house on the deck kept drowning. After the autopsies findings, they figure they should turn it over to build the wheel house and to make it easier to carry vehicles.
My father many years ago used to turn barges over when afloat by partially flooding them passing ropes over the hull to the far side and towing them broadside on The deck edge nearest the tug would go down the water inside the hull would rush down and over it would go No cranes just a tugboat
it was manufactured upside down because it's easier to lay a big steel plate and weld it rather than trying to lift all the big heavy plates and support them without flex while a guy stands under it and welds each plate. the prop and shaft were not installed yet due to the force of impact as it flops over would bend the shaft. no dummies here
Makes sense regarding the welding , easier that overhead welding process . Why not install the shaft and propeller too when the work areas are is exposed ? Thanks
Looking at the design of the hull no wonder in rough weather when the cargo shifts those ferries sink and roll over? That flat haul is a double edge sword!
ronstacie3 They had to haul the hull from the water in order to build the hall that houses the vehicles for transport. Before they flipped it over. Surely the checked for holes. Maybe the word, "holes," may have taken it too far.
TWTR4EVER No keel, a heavy load on the main deck, and no stability nacelles. It really does sound like these vessels should not be out in harsh seas. Whenever there is a small craft advisory, ferry ships should not sail.
Indrid Cold Back in the 1980's I did a crossing at the beginning of winter of the English channel from Dover (England) to Calais (France) in a ferry called "The Herald Of Free Enterprise". A few weeks after, the same ferry crossing I believe from Rotterdam or Amsterdam (Netherlands) back to Dover (England) in a storm, the ship capsized!
Herald of free Enterprise capsized when leaving Zeebrugge port 4 minuts after passing the last mole. Here bowport was still open when coming out in heavy seas.
Barges and work platforms are flipped over for a number of reasons. When a flat bottom barge is flipped though it can be done with a 10 horse pump. The sleeker shape of that hull bottom,, I've no idea if the cheap trick would work. just don't know. Barges are flipped by filling to about half full and then roll them over, then pump out again. The flip can be accomplished with dock lines and gravity. May not be deep enough in that river.
I worked in a shipyard in San Diego (not National Steel) & we built tuna seine 1200 ton net load and we launched the bottom of the ship upside down and then flipped it hauled it back onto the building ways and added the top and relaunched several months later
It may be a good idea for them, considering the different logistics. It could as well be that this method was invented by Norwegians to suite special conditions of ship building.
I can see a cluster of tiny boatyards from the bridge on my way home, and one day I was shocked to see a capsized barge bobbing in the tight confines of their tiny inlet! Subsequent trips confirmed that they had simply careened the thing like a rowboat and dragged it up the ways to work on the underside. How they managed this with the small space and limited equipment available, I have no idea.
I guess they wanted to get both sides wet. Those tugs are quite maneuverable. Quite a bit of strain on those large cranes from the cable whip once the hull was righted.
I researched this one and apparently the hull was designed in the Southern hemisphere, they did not take this into account during the build and had to wing it.
Any boat I think I ever seen built was built right side up and launched into the water. Apparently ferries are built and launched upside down then rolled over.
Because it was built upside down. It's far easier and less damaging to turn the hull right-side-up in the water in this case. If you turned this hull on land it would require massive setup effort. Normally, if you build a small hull upside down you don't have a deck on it which would allow this kind of operation. Also, the superstructure and fit-out can now be completed afloat, freeing up yard space for another build.
I think this is an ingenious design. It appears as though they are taking into consideration cargo door failures at sea which result in the flooding and sinking of many ferrys. If the hull is not exposed to flooding it wont sink...like a single huge pontoon....even if the ferry rolls over it wont sink giving everyone a better chance of survival.
Makes sense. Lot easier to build a ship hull upside down than right side up. The same massive cranes will lift the engine and superstructure into place.
Its only the bottom of a Ferry so they are still working on it. Maybe they cant flip it over in the boat shed to keep working on it so use the water to help flip it
Please understand, I know nothing of shipbuilding, but I have to ask, why the hell don't they just build it / put it in the water right-side-up in the first place?
They should have left it like it was when first launched. Imagine this...you're on a Carnival Cruise or the like, lounging out on your balcony and having the time of your life, and then this thing cruises up to your ship. I don't know about you, but I would be scared shitless!!!
I've been building commercial fishing vessels to be used in the Gulf of Mexico and on the East Coast of the United States in the Atlantic since the 1970's. I can think of a very few reasons, ( Moronic at Best ) , to flip a vessel W/O it's shaft and propeller.
Making a hull involves a LOT of welding. You choose: Welding over your head, hot metal dripping in your collar, or welding at the same metal by you feet, standing over it all? I *really* dislike molten metal in my collar.
Millions and millions of years ago, DINOSAURS roamed the Earth... One day, a mommy dinosaur came to realize she could love a daddy dinosaur very, very much.
In order to design this process to flip the hull over, engineers would have to do the structural analysis to ensure no harm is imparted on the structure from the lifting operation used to flip it. There is inherent risk in this kind of loading because Engineers often overlook important details because they are human. The worst case would be if this loading during flipping would be responsible for adversely affecting the structure thereafter and could result in some kind of disaster if design and Analysis where improperly performed.
probably due to the prop an the prop guard being there? they probably didnt want to scrap it all off so its better to keep the hull intact than have it be damaged.
Several people have got it! The designer comes back at 3:00 - "No! No! You've got it wrong! It's a stealth hovercraft for the US Navy Seals - you'll have to re-capsize it again. Sorry lads!"
I thought they would pump it full of water, play with the center of gravity, get it capsize, and them pump the water back out, but they used cranes instead. If you just happen to have some big cranes handy, well.
