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This ones going to leave a mark

crane operator

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Anyone have any insight as to why this heavy lift ship was designed to lift over the side as opposed to most of the ones I’ve seen that were more like a pair of sheer legs over the bow or stern.? That setup is much more stable.

I think the idea is that the wind turbine motor, blades, and tower, are on the ship deck. They sail to where they are in the ocean, then swing and pick everything off the deck to build the wind turbine. The ones with stiff legs that dead lift over the front don't swing or have turntables, they have to move the boat to do everything.
 

crane operator

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But that isn't what I thought I saw in the video that shows the moment it parted. The block and cables and boom seemed to stay pretty much in their places at first, it was when the ship tilted back so the boom was beyond vertical that everything went sideways, literally. ]

I'd say that video is slowed down quite a bit, look how slow the boom is moving as it is falling over on the back side, it would come a lot faster in real time.

If you look close, the boom is moving upwards and toward vertical faster than what the ship is rolling. Its just a whole lotta iron moving at speed.
 

Nige

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G..G..G..Granville.........!! Fetch your cloth.
As per my post #59 above. The only way to prevent the ship rolling to port when 2500 tons was suddenly let go from the hook was to pump the water ballast out in a heartbeat and that was never likely to happen. The unbalanced force caused between the X tons of ballast on the port side of the ship vs no load on the hook on the starboard side is what caused the ship to roll to port and everything else happened as a consequence IMO.

in addition to that possibly the speed of roll to port plus the "spring" effect of releasing the load when the hook failed may have accelerated the boom point to such an extent that it continued to raise even when the ship stopped rolling to port. When the ship rolled back to starboard again the boom point went over the vertical with respect to the boom foot pins and that was all she wrote. If you pause the video at 0:12 the boom is already pretty much vertical with respect to the water surface and the ship is still rolling to port.
 

muzy

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Yup I agree with Nige . Buy I sure would have liked to seen more of the boom just to see how it reacted .
The blocks didn't really bounce far . a calculation knowing rope size, how many parts and what they were pulling would determine estimated stretch . But if I knew how to do that....I would probably have a lifting licence.
Where is Sheldon when you need him?
Cheers
 

Natman

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And there lies the root cause of why it went over. There would’ve been no way to pump 2500 tons of water out of the ballast compartments to compensate for the loss of the load in a couple of seconds. Therefore the ship was always going to roll big style away from the load (that fella Newton again). With the test lift being performed at a fairly small radius it wouldn’t take much in the way of roll for the boom to go past the vertical position.

Anyone have any insight as to why this heavy lift ship was designed to lift over the side as opposed to most of the ones I’ve seen that were more like a pair of sheer legs over the bow or stern.? That setup is much more stable.

Showing off? Meaning, demoing their superior engineering, Figured they could make it work and gain some practical advantage in the ship crane business? The entire concept is out of my and most here work experiences for sure, sure is a interesting way to do a lift though.
 
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