Hurricane Energy Share Discussion Threads

[fatnacker] 13/2/2019 08:02

TG that's if the assumption that the failures were caused by the sea state is correct, I'm not convinced.

[the guardian] 13/2/2019 07:54

With three failures in the bag, I cannot see Bluewater taking any risks on attempt four. To that end, I don't believe that they will try in marginal conditions or when they are pressured by a small window. Better that they wait and get it right.

[gary38] 13/2/2019 07:51

I am looking on the Windy site for WoS buoy area Prefab.

[prefab] 13/2/2019 07:07

Looks very marginal at the weekend Gary, I'd be happy to be proved wrong though.

[gary38] 13/2/2019 06:08

Looks like a possible Weather window from Friday to Monday.

[gary38] 12/2/2019 23:21

Grampian sovereign is back in dock.

[playful] 12/2/2019 23:00

It’s a tad concerning our ropes are breaking makes you think we are sailing on the bounty...Up the rigging stow the sails!

[eggbaconandbubble] 12/2/2019 19:28

sf5 - Sounds like the 'Having a bath together' section of the Kama Sutra!

[sf5] 12/2/2019 17:03

The Maersk Peregrino video (minute 25-26) suggests maximum strain is just before the clamps are engaged - they hit 595 tn out of a 600 tn operating limit Presumably the buoy has to be pulled tight against the annual seal. And the top part of the buoy will be out of water at that stage and so provide no buoyancy lift that it had when fully submerged. It's not hard to imagine that a significant swell and relative motion (vertical or horizontal) between the two vessels at that critical stage will max out the strain in the rope.

[enfranglais] 12/2/2019 16:59

As this is the "rope a dope" board, where is gary?!!!!!!!!!!

[davidblack] 12/2/2019 16:34

Telbap well put.

[telbap] 12/2/2019 15:50

You are the worst type of spamming £&@" there is. Fu@k right off!

[daniel levi bmd] 12/2/2019 15:19

FYI

Andalas Energy & Power. Honesty Is The Best Policy! Hold For Colter

Dan
x

[greyingsurfer] 12/2/2019 15:05

They didn't reuse the snagged rope. They used the spare.A 2m swell may not sound much, but you have to remember that the seas rarely, if ever are made up of a single smooth swell. In practice, there are often two overlapping swells, from different directions, as well as waves, which may be several m high from yet another direction. The AM cannot be held straight into all of them at the same time. So while she may be head in to a 2-3m swell, most of the time there will be waves, or other swell hitting her sideways, and of course as the beam is much less than the length the effects of waves side on are significant. The result is going to be uneven movement, with little predictably, in several directions. Those movements will put large dynamic loads on the pull up equipment, winches and rope, and if they are trying to fit a close fitting 1200 ton buoy into a socket the potential for excess loads or damage is considerable.I suspect, that with hindsight, Trice might agree that his statement that they only needed 6 hours with swells lower than 3m was over optimistic. And after all, that is Bluewater's expertise and responsibility, not his. Though, of course we don't know what they had advised beforehand.

[jacks13] 12/2/2019 14:52

Hoolio, If you are saying they used a damaged rope on the second attempt then fair enough. The RNSs don't refute that, so it could be so.
fatnacker, that's the thing I can't square. The sea conditions were within their target envelope. The buoy/turret system doesn't require the dead weight lifting of the buoy clear of the water. Buoyancy aids the lifting.

[fatnacker] 12/2/2019 14:46

Jacks, the sea wasn't heaving, less than 2 mtr swell, check out the size of the ship compared to a 2 mtr swell and you get a perspective

[hooliogeordio] 12/2/2019 14:37

The rope was snagged on the attempt prior.

[jacks13] 12/2/2019 14:25

I remain puzzled by the rope failures and none of the discussion I’ve followed here and elsewhere has shed much light on my doubts. I fully appreciate that the heaving sea will have created uncontrollable dynamic forces etc but perhaps someone can explain the likely events as they read them in light of the following:

Extracts from the EPS Environment Statement:

‘Once in the field, the buoy will be sunk to a working depth using its own ballast, assisted by a clump weight buoy which will be placed on the seabed. Sinking the turret buoy will reduce the forces required to pull the mooring chains into position and the hook-up duration.Once all of the mooring lines have been connected, the clump weight will be recovered and the turret buoy will be de-ballasted. Once installed, the turret buoy will remain submerged in the water column until the FPSO comes onsite later in the year.’

And:

‘When initially connected to the mooring lines in the field, the buoy will sit 20 m below the sea surface and a surface line will be used to pull it into the FPSO.’


I’ve read somwhere that the new buoy is more robust than the old one, so it is reasonable to assume it will be heavier. I’ve been unable to find the weight of the old buoy but dimensionally it will be of similar size although it may have been fabricated from heavier gauge steel. The mating section, that is the upper conical part, will have had to have been made to the same dimensions as the old buoy. The lower section, the annular float chamber part, the part that remains external to the hull, may have been made larger. Overall the new buoy shouldn’t be significantly heavier than the old one I would think, particularly as a larger annular section would, when de-ballasted, have compensating relative buoyancy.

The horizontal surface that forms the upper deck of the annular section is located close up against the belly of the hull once the conical section is located into the turret. Seal(s) fitted onto the conical section will have been pushed against the turret internal conical surface and the upward buoyancy forces will have both closed the seals and delivered the locking ring into place, ready for the twelve locking rams to secure the assembly. In other words the annular buoyancy chamber never leaves the water and furthermore the buoyancy of the chamber actually serves to deliver the cone section into place. So what are the tensile forces on the rope? I haven’t the wit to work it out but I remain puzzled that a 600 tonne breaking strain rope should have broken.

[marvelman] 12/2/2019 13:53

Thanks bounty/fatnacker...not as simple as investing in a supermarket stock but far more interesting

[fatnacker] 12/2/2019 13:52

I think you're correct bh, divers.

[fatnacker] 12/2/2019 13:49

Got you now marvleman, it was the rope used in the final stage just prior to putting in the locks.

[bountyhunter] 12/2/2019 13:49

marvelman, the buoy is only 20m below the surface so presumably they could send a diver down to assist the ROV if necessary, in any case I would assume that their is an established procedure for attaching a replacement rope whatever that may be so shouldn't be a showstopper given suitable weather conditions

[greyingsurfer] 12/2/2019 13:46

Thanks Buzzz, someone has certainly posted here that a replacement for the first rope was ordered after it got snagged. I'm amazed it would take as long as 3 weeks, but it doesn't make much difference, since 3 weeks has about passed anyway.

It's quite clear that the hold up has nothing to do with replacement. There isn't currently a weather window.

[rayrac] 12/2/2019 13:42

If only it were as easy as shown on YouTube? You just can’t rely on rope makers these days, out for fast buck...or slow as the case may be. :(

[marvelman] 12/2/2019 13:39

Thanks Tournesol..I don't feel quite so stupid now. I am well aware that I am in the presence of some very learned experts on this board and I therefore think hard before I ask a question. The reason I asked in the first place was to get an idea of the logistics involved in securing a new rope to the buoy. There appears to be an eyelet on the buoy which is where the rope is clipped on to and I therefore wondered whether an ROV would be capable of detaching the broken rope and re-attaching a new one. Clearly this might be a more problematic operation than one would think when than just replacing a broken rope.Regards