North Sea Tug Roll's Over

[toesup]

http://news.bbc.co.uk/2/hi/uk_news/scotland/north_east/6552467.stm

The Burbon Dolphin rolls over in the North Sea Thursday... possible loss of crew members.

[smart_racer]

Not good news to read about missing crew, plus a 15yr old boy... keep your fingers crossed.

[Ghost 2501]

what was a 15 year old doing on the ship anyway???? even though he was the son of a crewman

[Umi_Ryuzuki]

They have been discussing this yesterday, on Shipspotting, almost as it happened... Apparently, there was no mayday or distress call from the ship.
. It happened that suddenly. :(


Two of the missing is father and son. The son is 15 and where onboard as a school related introductory to work.


http://www.stv.tv/content/news/main/display.html?id=opencms:/news/Three_die_after_oil_rig_support_vessel_c

Bourbon Dolphin (http://www.ulsteingroup.com/kunder/ulstein/cms.nsf/pages/reflista.htm)

[Jerome Morris]

Guys, I found this on Cargo Law.
75.2mt. Norwegian-registered tug supply M/V Bourbon Dolphin, with 15 crew -- as oil rig anchor handling tug capsized in the Atlantic 75 miles west of the Shetland coast. Rescue teams rescued 10 crew, but 3 of these died & 7 are in hospital -- 5 additional crew missing. A coastguard spokeswoman said it would be a "miracle" if the missing crew members were found alive. The ship, which is less than 1-year old, had been working in the vicinity of the Rosebank oilfield with a crew of 15. Six Royal Navy divers were flown to the boat from Faslane on the Clyde. It is thought that the 5 missing crew may be trapped in the hull of the upturned vessel. Rig operator Transocean said the 99 crew members of the Transocean Rather had been accounted for. M/V Bourbon Dolphin had a number of roles in the North Sea, including anchor handling & towing, the installation of subsea construction blocks & operations involving remote vehicles. From our Correspondent Les Crossan (Fri. April 13 2007)

[Shaun Hendricks]

Whoa.... hows this for odd. That was the same tug that pulled the German "Duke's of Hazzard" Mine hunter off the rocks:


The Cargo Letter for Feb. 24 2007 -- Grömitz Freed By The French.

660t. German Navy minesweeper M106 Grömitz -- refloated by 2974t. French anchor chaser M/V Bourbon Dolphin after 3 attempts of smaller tugs had failed, on Feb 22 at 4.51 p.m. with the rising flood. M/V Bourbon Dolphin pulled M106 Grömitz with the power of its 16300 hp into deep water. Then she was escorted to Hakonsvaern for inspections. From our Sr. Correspondent Tim Schwabedissen. (Sat. Feb. 24 2007)


I knew I'd seen that name before!

[Kmot]

Tis a sad accident. A brand new ship/tug and this happens. The 15 y/o was getting 'work experience' I read on another site.

[Ghost 2501]

Someone has a really hard job now, teling as relative that two loved ones will not be comming home, not easy.

[bigford]

just found this on the bbc site
they got her free of the anchor

The ship's operator, Bourbon Offshore, had hoped to tow the vessel back to shore.

Describing the ship as "very unstable", Shetland Coastguard watch manager Neil Cumming said: "It was released from a rig yesterday and slowly it began to sink."

It is now thought unlikely the Bourbon Dolphin will be raised from the seabed, about 3,500ft down.

[Umi_Ryuzuki]

A little more info...



This account from The Herald in Glasgow, if it can be substantiated, may give some clues:

"According to witnesses, as the vessel headed away from the Transocean Rather drilling rig with one of its anchors, it seemed to turn sharply and the anchor chain jumped out of the mechanism at the rear of the deck which held it. As the chain ran across the deck, the 75-metre tug lurched one way, then the other, before overturning."





...Earlier, one of the survivors, seaman Egil Hafsas, told how his life was saved by his love of nature - he had been on deck watching the waves when he felt the vessel lurch to one side, then the other, then back again before rolling over completely.
...

"The Glasgow Herald" (http://www.theherald.co.uk/news/news/display.var.1330122.0.shipmates_and_loved_ones_uni te_in_tribute_to_five_missing_seamen.php)

[toesup]

The Bourbon site...

http://bourbon-online.com/Bourbon-dolphin-En

[marinaru_ro]

This was the ship...
Nice tug, but it's gone now

[Tugboat Andy]

The April 2008 issue of MarineLog has a short article about the loss of the Dolphin. Basically the preliminary report:

"...points to a series of circumstances that acted together to cause the loss of the vessel. One of the proximate causes of the accident was the vessel's change of course to port so as to get away from mooring line no. 3, at the same time as the inner starboard towing pin was depressed, causing the chain to rest against the outer port towing pin. This gave the chain an altered point and angle of attack on the vessel. Together with the vessels current load condition, the fact that the roll reduction tank was probably in use, and the effect on the vessel and the chain of external forces, caused the 2974-grt vessel to capsize."

According to the article, you can view a simulation of the accident at WWW.marinelog.com/DOCS/NEWSMMVII/2008mar00280.html

Ooooooh! BTW - this is a cool website! A great video of a Bourbon tug on a breezy day! :cool:

[Brooks]

Monday morning quarterbacking by a model tug skipper - If the video graphic is correct, there is no mystery why the vessel capsized. The ship was "girt", meaning that the towline (= anchorline in this case) was not leading over the stern, but was leading over the side. Tugs are quite sensitive to lines leading over the side, and a capsize is often inevitable in that situation. In the days of fiber lines, an axe was kept handy just for this reason.

With the anchorline pinned to lead astern (to avoid girting), the rudder/kort nozzles/any thrust from aft of the CLR would be ineffective in steering. The only force to keep the bow on course would have been the bow thrusters (I assume the ship has them). The wind hitting the high superstructure forward of the CLR may have simply overpowered the bow thrusters. They were not strong enough to do the job, or there was a mechanical failure.

Once it became clear that the vessel could not maintain course across the wind, the skipper likely tried to change the angle of the anchorline wrt the tug's hull, hoping to make the rudder more effective. The pins on the taffrail, holding the anchorline in position, were pulled (sunk into the rail, I imagine) on purpose. This allowed the boat to turn under the anchorline and point upwind. The new athwartships angle + weight of the deployed anchorline + perhaps a downwind trending current pulling on the anchorline, all worked to capsize the ship.

The necessity to turn upwind was brought on by the ship's proximity to the already set anchor to leeward of the proposed anchor being carried. Setting the downwind anchors before completing the upwind anchors was poor seamanship. W/o the interferance of the downwind anchors, the tug could have simply dropped the anchor it was carrying.

Actually, that option was available at any time prior to drifting down upon the set anchor.... the skipper should have abandoned the attempt as soon as it became apparent the ship could not maintain course. By waiting until dropping would possibly foul the set anchor, he ran out of options. Of course, dropping the anchor on the already set anchor would have been preferable to the capsize, so I must say the skipper was not displaying good judgement at any time in the evolution.

[toesup]

If the video graphic is correct, there is no mystery why the vessel capsized. The ship was "girt", meaning that the towline (= anchorline in this case) was not leading over the stern, but was leading over the side. Tugs are quite sensitive to lines leading over the side, and a capsize is often inevitable in that situation. In the days of fiber lines, an axe was kept handy just for this reason.

Watching the reconstruction again, i would have to dissagree that the Tug was 'Girt' Brooks. The line was still over the stern, but at an angle a modern vessel should of been able to handle.
Modern tugs, especially the more recently designed tugs, both sea going and harbour tugs are able to have the line at nearly 90 degrees to the tugs CL and are able to manouver with the line in this position.

I will agree that the Captain lacked good judgement in the way the procedure was handled.

[Brooks]

Thanks for the comment Toes, it made me look into the situation in more depth.

Narrative of the accident by safety-oriented mariner Bob Couttie. Includes problem with thrusters:
http://maritimeaccident.wordpress.com/2007/10/26/the-death-of-the-bourbon-dolphin/

The Norwegian report, in English:
http://bourbon-online.com/media/dolphin/Dolphin_report_080328.pdf

Dolphin "almost capsized" before:
http://www.energycurrent.com/index.php?id=2&storyid=3195
The incident, on page 59 of the Norwegian report, does not appear to me to constitute "almost capsized"; an 18 t anchor slid across the deck and caused a 5-7deg list. The report states that this incident should have alerted the company of the need for further stability calculations for the Dolphin.

Couttie's summary of the accident report findings (includes a typo regarding the pins, corrected further down the document):
http://maritimeaccident.wordpress.com/2008/03/29/bourbon-dolphin-report-released-tug-stability-captains-competence-not-checked/

[Shaun Hendricks]

Okay, I have some 'dumb' questions:

First: Why are Anchor Handling Tugs designed with so much superstructure mass?

I can see why the X-bow might be popular, it would increase wave piercing ability and decrease topside mass. However the tumblehome would make it not want to recover from a roll as well... so, unsure if there's a design problem here but I would think all that mass up high certainly wouldn't help a tug going into a list condition.

Second:

Why the heck did they release that inboard pin? From the animation, it didn't take a rocket scientist to see what would happen. You'd have to crank the vessel the other direction to keep it from happening.

Third:

The tug helping the Dolphin seemed completely incompetant by the reading. Shouldn't they have stopped letting out more chain and just had another tug catch up to them and both pull the chain back into position? Clearly the Dolphin just didn't have the umph to handle the seas and that chain.

Fourth:

Why'd the captain go to bed? He had to know his ship was struggling from all the calls from engineering, unless this is the first chain they laid, and he should've been there the whole time in my opinion.

It seems to me to smack of pride here. When things started to get bad (Note to self; the next time Scotty calls up and says "She canna take anymure Captain!" it's getting 'bad') I'd have been winching *IN* chain or stopping and yelling for help. The worst thing would be a rearward drift due to weight while your engines throttled down to cool off and when help arrived you could both tow the chain out to position or winch back up to square one, call it a day and wait for better weather.

If those animations are correct, there is no excuse for the human behavior demonstrated. It certainly was not: "Safety First". People seem to be dead because of pride and poor judgement. Not the first time it's happened but certainly a preventable one.

I'd certainly smack around the crew of that second tug as well...

Chain of events, all accidents are traceable to a chain of events, pun not intended. :(

[Brooks]

The Norwegian report is quite fascinating to read. Though it is long, at 200pages, it is written with clarity. There are diagrams of anchor handling, and photos of the doomed tug taken the day of the disaster.

Some items of interest to me in the report:
Neat photo (for us model tugboaters) of chain grapnel page 94

Procedures were unplanned for ocean current problems (current was as much as 2x the expected current) page 101.

Forces on anchor handling tugs were underestimated by Chevron by as much as 35% due to simplified dynamic calculations. This meant that small tugs were thought to be sufficient.

The report blames Chevron for faulty rig movement procedures, saying it was Chevrons' responsibility to check tug safety and develop safety procedures. Chevron responded that it was the skippers responsiblity < I must say the Norwegians attitude appears to be blame shifting to me>.

Great photos of the Dolphin's anchoring operation right prior to the capsize page 128+

Photo of Dolphin's stern deck, with anchor, chain, and towpins, prior to capsize page 131.

"The proximate cause <of the capsize> is the angle of attack that the mooring line gradually acquires in relation to the vessel and the tension in this line." page 154.

Evaluation pg 155-160 is a good summary of findings.

-----------
As Toes observed, this was not the girt situation I thought; the chain did not, in all probablility, shift to 90deg and lead over the side of the tug. It is even more interesting :-). The Norwegian report states that the angle of attack of the anchor chain relative to the tug was the reason for the capsize. But, the chain was retained by the towpins, so probably never led over the side as I thought (the ROV observed marks on the winch that suggested the chain at some point did lead over the side, but that may have happened after capsize or during the sinking). Rather, the force downwards (100t) applied by the anchorchain (at first the inner starboard pin, then the outer port pin), plus, the 60 degree angle of attack of chain away from the extended centerline of the tug, led to the creation of an overturning moment. The off-centerline pull was the problem, even though it was pinned to only 1.75m off-center, an unexpected conclusion to me (but backed with copious, post-sinking engineering calculations).

The ship did not have as much stability as expected; during building, weights were added above deck in excess of plan. The ship employed a complicated ballasting procedure, including roll damper tanks. The crew likely did not understand them. Moreover, they were never informed of how using the roll damper tanks might easily lead to instablility problems; this information was requested by the captains from the builders, but for some reason was never supplied. The captains of the tug had noted that they needed to keep full bunkers for good stability, but that information was not seen as a red flag to the tug owners or tug builders.

The oil rig did not help the tugs as much as it could/should have. They could have reduced the stress on the anchorline by spooling out cable, thus making it easier for the Dolphin to regain course. This technique was used when setting the other cross-current anchor, but only after the tug setting that anchor repeatedly asked. In general, the towmaster on the oil rig did not act as if it was any of his responsiblity to help the tugs do their job, nor, especially, to act in a proactive manner when things started going wrong.

The report notes that the progress to the capsize took several hours - this was not a case of something happening quickly. There were many places along the way where it would have been possible to stop the situation from deteriorating further. The accident chain had many links, but no one took responsiblility to sever any one of them, unfortunately.

[Brooks]

Shawn, good questions, here are my thoughts after reading the report:

1. High superstructure - like you I thought that a liablility....but, the report says the lack of superstructure aft is a bad feature for these tugs. When a tug like this heels, it has no superstructure aft to make a lifevest, ie, there is no buoyancy generated for righting a half-flipped hull. Eg. if a 2x4 is floated on it's side, there is nothing to keep it from turtle-ing.

2. There was controversy in the testimony on who ordered the starboard pin to be depressed, allowing the chain to whip across to the port pin. So, the people testifying all tried to make someone else take responsiblity, recognizing, as you did, that this was a bad move. The skipper of Dolphin, who did not survive, probably did it to get a better angle and make his rudder more effective. He did not realize that letting the weight of the chain move to the port side would be dangerous to stability. He might have been thinking as I did: namely that the girting danger would only occur if the chain led over the side, and that there was no danger as long as the chain always led over the stern. Looking at the photos of the stern, it does seem inconceivable that letting the chain move less than 2 meters off center (for a tug 17m wide) would pose a problem. And that would be true IFFFF the chain had not been leading off at an angle (estimated by the report at between 40-60 degrees at capsize).

3. The grapneling of a chain during deployment, for the purposes of helping the far tug regain position, was never practiced, nor was it described in the anchor handling procedures manual. This was something, you might say, dreamed up on the spot. Neither the rig nor the grapneling tug knew, for example, how much line to let out on the grapnel so that it could snag the anchorline- there were no charts/procedures/etc. to follow. The tug did, infact, catch the chain on their 2nd attempt, but they were unable to use their pull to advantage and assist Dolphin. One of the interesting things in the report concerned the lack of use of knowledge from the previous tug's difficulty with cross-current ops. The 2 tugs that successfully set the 1st cross current anchor were the 2 largest in the fleet....and They barely made it. The 2 tugs assigned to the last anchor, Dolphin and Highland Valor, were the two smallest tugs.....duh?

4. Neither the Dolphin's skipper nor his 1st officer had much experience with anchor setting. The skipper did not even have much experience aboard Dolphin - this was his first trip, I think it said. Normally a new skipper travels with an experienced skipper till he gets the feel of the ship (that was the stated policy of the tug company). For various reasons, which are unclear to me, this procedure was not followed this time. One visitor to the bridge of Dolphin prior to the capsize testified that the skipper, to him, appeared excessively calm/passive about what was going on. Another visitor refuted this in his testimony. But when someone is in over their head, passiveness can be a response mechanism....I don't know if that was true here, of course. I do think pride played a part, as you said. The commission also said that maybe get-done-itis was also a factor - the planned 5day move of the rig had taken 18 days, this was the last anchor, etc.

[Tugboat Andy]

Wow, there is a lot of information here! I guess I know what I am reading with my morning coffee tomorrow. ;)

Can some explain the roll reduction tank? I assume it helps dampen ship motion and better allow for dynamic positioning?

NOTE: If you look at the movie of the overturned hull, you can spot the extended z-drive at the bow of the Dolphin.

[Brooks]

Tugboat Andy - re roll reduction tanks: I can only relate what I read in /understood from the report, not being a nautical architec - This hull design has a tendency to roll a lot, which is uncomfortable for the crew. The roll tanks were installed to make ocean travel more bearable. They were not to be used during anchoring operations.

I think the potential problem with these roll reduction tanks was that they raise the center of gravity. The GM, metacentric height, is very low on these vessels, ranging from 29cm to 110cm. Metacentric height is a measure of righting ability, with low GM's having less ability to right the vessel than high GM's. GM is sort of the distance between the center of buoyancy (hopefully high up) and the center of gravity (hopefully low down). By running with the fuel bunkers full, the cg was kept low, which is why the captains preferred that condition with Dolphin.

I am not sure the roll tanks were used during the operation, except at the very end - the 1st officer attempted to ballast the starboard tank to fight the list to port. It almost sounded like he did this right before he bailed out (but I may be confusing ballasting with the emergency release of the anchorchain).

The capsize sequence was:
1. shift the chain from starboard to port (big clang as the chain whips across against the port outer pin).
2. vessel takes a big roll, possibly 30deg to port; crew below realize something is wrong and start to grab lifejackets.
3. the vessel recovers.
4. the vessel takes another roll to port and lays over.
The officer struggles with the starboard bridge door, which fights opening due to gravity. He sees the Captain and his son struggling below him; no one sees them again, so it's not known if they exited and died of exposure, or if they remained trapped in the bridge cabin. Rescue divers attempted to ascertain the location of unrescued crew, in case some were trapped in an air pocket. The weather was bad, and they were told not to enter the ship (which was floating upsidedown). They reported that they were "95% sure" no bodies were in the bridge cabin. These details, along with the photos, were hard to read, as you can imagine.

The tug was a dual purpose vessel, both "anchor laying/recovery" and "supply delivery". Oil rigs need liquid supplies, such as brine and drilling mud, so Dolphin had a number of cargo/ballast tanks. If these tanks were filled with seawater for ballast, they had to be cleaned before cargo could be put into them. The report suggested that the expense of cleaning may have influenced the skippers to run with the ballast tanks dry.

No one knew that the tug was so marginal wrt stability, apparently. She had passed the official Norwegian stability tests; it would seem, in retrospect, that those tests, while sufficient for a cargo vessel, were not capable of predicting vessel behavior in oil rig anchoring situations. There were no Dolphin-specific loading vs. stability charts to assist the skipper in preparing for anchoring ops. The report was quite critical of this deficiency, seeing as how anchoring was a particular specialty of the vessel.

I hope you read the report Andy, and if I made mistakes in interpretation, please correct them, thanks.

[Tugboat Andy]

I hope you read the report Andy, and if I made mistakes in interpretation, please correct them, thanks.

Many thanks, Brooks! :) I appreciate the amount of effort you have put into reading up on this. Looks like a rainy pacific northwest day tomorrow so I may dig in and read up on the Norwegian report. It sounds like there are many interesting things to look at.

I watched some videos of tugs setting anchors / handling lines and was absolutely awed at some of the working conditions filmed. WOW!

[Shaun Hendricks]

1. High superstructure - like you I thought that a liablility....but, the report says the lack of superstructure aft is a bad feature for these tugs. When a tug like this heels, it has no superstructure aft to make a lifevest, ie, there is no buoyancy generated for righting a half-flipped hull. Eg. if a 2x4 is floated on it's side, there is nothing to keep it from turtle-ing.

Yes, boyancy is good, but only works until the cavity is 'in' the water and if the ship weren't buttoned up fully... (which is frequently the case)


2. There was controversy in the testimony on who ordered the starboard pin to be depressed, allowing the chain to whip across to the port pin. So, the people testifying all tried to make someone else take responsiblity, recognizing, as you did, that this was a bad move. The skipper of Dolphin, who did not survive, probably did it to get a better angle and make his rudder more effective. He did not realize that letting the weight of the chain move to the port side would be dangerous to stability. He might have been thinking as I did: namely that the girting danger would only occur if the chain led over the side, and that there was no danger as long as the chain always led over the stern. Looking at the photos of the stern, it does seem inconceivable that letting the chain move less than 2 meters off center (for a tug 17m wide) would pose a problem. And that would be true IFFFF the chain had not been leading off at an angle (estimated by the report at between 40-60 degrees at capsize).

There appears to have been almost 160-180 tons of chain out to overcome the ships pull rating. Any captain with any time experience should've known that shifting that amount of weight any distance is too much shifting. There was nothing significant to be gained by dropping the pin and imagine what would've happened instantly if the outboard port pin sheared or was jumped by the chain, the risk factor was HUGE.

They weren't going starboard because they were using the starboard pins, they were going starboard because the wind and seas were moving them that way, the captain had to know that. All of their engine power was being used just to counter the weight and effects of the chain, they had nothing left to counter the conditions. No amount of rudder effectiveness was going to move them back on course in those seas with that dead weight. The right call would have been "Abort for today, conditions too severe to continue".


3. The grapneling of a chain during deployment, for the purposes of helping the far tug regain position, was never practiced, nor was it described in the anchor handling procedures manual. This was something, you might say, dreamed up on the spot. Neither the rig nor the grapneling tug knew, for example, how much line to let out on the grapnel so that it could snag the anchorline- there were no charts/procedures/etc. to follow. The tug did, infact, catch the chain on their 2nd attempt, but they were unable to use their pull to advantage and assist Dolphin. One of the interesting things in the report concerned the lack of use of knowledge from the previous tug's difficulty with cross-current ops. The 2 tugs that successfully set the 1st cross current anchor were the 2 largest in the fleet....and They barely made it. The 2 tugs assigned to the last anchor, Dolphin and Highland Valor, were the two smallest tugs.....duh?

Definitely 'duh'. I'm not sure why they tried the grappling thing anyway. Wouldn't it have been more practical to fire a tow line to the Dolphin and have the Highland Valor pull the Dolphin by the nose as both tugs put their power on the right course? Locomotives do this all the time, team up and pull (or push) each other. I have no clue why they were even messing with the chain, it's just dead weight and trying to use a tug as a 'fishing bobber' to help the lead tug sounds really dumb to me. Their foes seem to have been the weather and length of chain they had out, decreasing the apparent 'weight' a bit by lifing the chain would accomplish little. And if the lifting line 'snapped' or let go, suddenly the lead tug is REALLY out of position and now has the whole burden plus whatever they let out again. They are in worse shape than they were when they grabbed the chain. If anything good comes out of this, it might be that this grapling thing comes out as a no-no.

What gets me in this whole situation is that there were a number of experienced sailors involved. The rig crew had to have some experienced people and yet nobody dared to tell the Dolphin's Captain that he might be headed into trouble. Nobody offered, "Hey Dolphin, it looks like this isn't working as you are still drifting. How 'bout we reel in and take another stab at it tomorrow. It's not like my oil company didn't just make a few billion dollars in profit last year."

Instead, everyone let an inexperienced Captain make poor decision after poor decision. He's the Captain after all, and Captains never make mistakes....

[Tugboat Andy]

I still need to read up on the Norwegian report.

I read today in Professional Mariner Online (?) that the mains shut down and the Dolphin has lost power. It sounds as though during the lead up to this the engineer was "threatening" to shut down power to the thruster as it was over heating. I believe that the mains shut down after the list. I wonder if this was caused by low oil pressure?

A blog comment compared anchor handling to some sort of black art whose seceracy is highly guarded. I have seen a couple videos on You Tube of anchors going over the stern but no grappling hook operations. Maybe this should be a new event for FOSS CUP?

RE: Highland Valor. I am speculating that they may have made the problem worse if they had tried to tow the Dolphin by the bow. The only tow point on the bow is high above the center of gravity and the leverage created by them trying to horse the Dolphin around after they had laid out all that chain in the wrong direction might have just laid them right over.

[Shaun Hendricks]

You might be right there Andy... but they probably could've rigged a bridle to each side or something. At the very least, hook on to the chain a hundred meters back and help tow the head chain.

I am certainly not a tug expert, but common sense in physics would dictate that there had to be a dozen or so other actions they could've taken than the ones they did.

Putting an inexperienced Captain on an untested, underpowered boat out in that weather is one of the dumber things I've ever head of a company doing. There is plenty of blame to go around but there are a few less people around to be pointing fingers. Sadly, they died with the Dolphin.

This is what bothers me the most. If it was just the ship, I'd say the company got what they deserved. If it was the Captain and the ship, I'd say the fool killed himself and his boat, a tragic waste. Instead we have many people down to a boy that paid the price for pride and haste. That is beyond tragic waste to just tragic.

My heart goes out to these families and I guess part of the anger I feel is probably an echo of what they must be feeling. This could have been prevented, like any accident chain, at a dozen different places and yet, here we are.