I was talking about the anti-heel system not being designed to compensate for such events.
There was; Probably well before the “Vertical point” when the vessel was not listed. I.e. to stop the crane boom from being topped passed a certain angle to horizontal. (Probably by other means than physical stops, not mechanical)
Nothing could stop the boom from buckling when it hit the A-frame at such high speed (impact force at lower end of boom would have been immense)
BTW: The boom is NOT designed to accept large bending forces.
Big seatbelt-type inertial lock on a guy rigged below the boom?
The reactionary list of the ship made the crane boom go beyond its working limits (vertical) not the loss off the load on the hook. Had they not prepared for that possibility to happen? Had not prepared for loss of hook load without putting crane into a perilous situation? Hook loads are lost for a variety of reasons in this business, not the first time for sure. And for the other dumb dumbs no one is saying that an anti heel system can keep up with a situation like this. We were talking about pre-ballasting and during load automatic ballasting by the system.
Or instead of a physical mechanism a procedure in place that provides for the vessel to never roll crane boom past safe point at loss of 100% of hookload or crane load?
I haven’t seen anything stating the capacity of the anti-heel tanks, or any video showing the Orion 1 before taking any weight on the crane, but I would guess that they had pre-ballasted in other wing tanks to where the ship would be upright at about 1/3 to 1/2 load. (Guessing, since I don’t know the ballast plan, or capacities)
In that case the anti-heel system MAY not even have been activated yet at time of failure-
ITC the ship would stay listed until they could de-ballast by the ordinary ballast pumps,(Which it look like it did)
Too many things are unknown to spend any more time on speculating. Wait for the official report to be issued.
What we DO know: The hook failed, the crane boom snapped back a bit and the ship listed, causing the boom to get passed vertical, with nothing to restrain it, hit the A-frame and buckle.
Yeah obviously. I didn’t say it could accept bending force, I said a lattice is very rigid under that vertical loading of the lift. And therefore the shock of release of the lift is more translated to the pedestal and hull, not into “the boom snapping back”.
I’m also not “speculating” regarding the ballast situation or suggesting that anything was incorrect there, regardless of whether it was being operated manually or automatically.
A vessel heeling to its new center of gravity upon loss of load on the opposite side of the vessel is a given. Since this is a possible and foreseeable situation, it just seems to me to be an unacceptable design shortcoming if this purpose-built vessel can’t accommodate that with damage less than complete. I’d expect damage, but not total loss.
But yes, if the investigation sees light of day it’ll be interesting, but as a private commissioning event I wouldn’t expect the report to be made public.
Looks to me like simple physics at work. If you can move enough ballast quickly enough this won’t happen Question of the day can you. It would be interesting to see the ballast plan and the dynamic stability curve for the lift.
Too many what ifs I’m sure the investigation will shed some light onto the operating parameters at the time of incident and any design short comings.
I thought this was interesting. It makes sense that the crane design should take into account sudden loss of load.
The design of the crane obviously has to account for the load but also has to dissipate the energy absorbed in the crane during a lift if that load is suddenly removed.
2 posts were merged into an existing topic: 5 inch 38 caliber gun
This vessel would have been the most capable heavy lift monohull vessel without the crane located roughly center line stern. Just maybe there was a reason why the designers of the Borealis, Strashnov, and other similarly capable vessels did not place their crane off center of the vessel forward of the quarter. As we know all of the big boys are semi-submersibles or sheerlegs.
Out of curiosity, from a DP standpoint would it be easier to hold position for a critical lift over the side versus over the stern of a monohull vessel?
Is the benefit of off-center that it can take lifts off her own deck to lift over the side? Seems like an easier ballast scenario to swing a lift 90deg vs 180deg.
I’d guess that a 5000mt lift astern from a stern mounted crane would cause unbelievable stresses on the hull longitudinals. I’d love to see the framing plans for one of those!
From a DP standpoint holding position with the lift over the stern or the side has little bearing on DP performance. The only effecting factors would be having to rotate heading around the wire and having to setup vessel for best motion characteristics versus environmental conditions. Rotating the vessel around the wire when positioned off the stern will put much more stress on the bow thrusters compared to rotating closer to actual vessel center of rotation. I doubt very many large heading changes are made during these heavy lifts. As far as vessel motion sometimes you have to orient vessel against prevailing conditions(current) which would make the vessel work harder to hold position. Making these lifts always requires attention to which way the lift will “flag” once in the water, clearance from hull, and thruster wash. Anchor handling puts much more extreme forces for the DP system to accommodate than offshore lifting does.
Yes I believe she was designed to carry out her own cargo as opposed to most of these other vessel that deploy heavy lifts from another vessel to the seabed. Crane mounted center line stern (vessel to vessel lift) would greatly assist in controlling list.
Regarding the hook failure, here’s a picture of a piece of a quick release hook that I carry on my key chain to remind me of why I have a rather prominent scar on my forehead. I’d rigged it as a gybe preventer, and it acted according to Murphy’s law. You don’t have to be a material scientist to figure out why:
My takeaway was that I should never ever trust my life to a piece of gear without testing it first. As someone pointed out to me, I didn’t have to buy a tested and rated hook for the purpose, just pull it with a winch until satisfied. Having designed and built some lifting gear, albeit on a much smaller scale than this, I know how rigorously such testing is carried out, and I refuse to believe that the hook in question wasn’t tested in a draw rig prior to installation on the crane. This leads me to suspect that installation error, rather than sub-par materials, may be at the heart of this.
The Preliminary Investigation report is out:
So the interesting facts are:
1.The crane was designed and built to the highest standards and was functioning perfectly before it collapsed into a pile of scrap metal.
2.The hook was made from the finest material available.
3.The hook broke and the crane collapsed.
4.We don’t know why but all the experts agree that it was because the hook broke.
The exact reasons as to why the hook did not withstand the load are unclear at this stage of the investigations.
Yeah, so the preliminary report preliminarily tells us nothing about the one thing everyone is interested in. How enlightening!
I hear the client supplied the hook, they are still looking for the certificates…( in China)
11 posts were split to a new topic: Orion 1 Crane Failure: ‘the ship could handle the “whiplash” effect, but the crane could not
A clearer video: > > > https://youtu.be/o1s79Uk10TA