Content: Something about the US Navy radar surveillance vessel SBX-1, A view about how the British navy submarine HMS Ambush came to collide with a merchant ship while submerged, comment about the latest Diamond Offshore semi-submersible the Ocean GreatWhite, a complaint about the offshore industry lack of interest in the skill of ship-handling, and ships being taken up as fish farms. 

The SBX-1 

The SBX-1 under way - Photo by the US Navy.

Back in July 2013 a towing event was reported the media which was of interest on a number of levels. The event was the snagging of an underwater cable by the tow wire of the tug Maulani when it was towing the semi-submersible SBX-1 in to Pearl Harbour, and it obviously raises the question, what the hell is the SBX-1. But first things first, apparently the tug had stopped and the tow wire had grounded on the seabed, cutting an essential security cable, costing over one million dollars to fix, and a claim against the tug company has been made by the US Justice Department. I would have thought that such essential cables should have been protected, but apparently not. And even so I tried to imagine how the catenary of a tow wire could snag on a cable, and was only able to do so if I accepted that the wire had some bits sticking out. But the SBX-1 - it is a semi-submersible with an enormous golf ball stuck on the top, which is apparently the protective cover for an X-Band radar system. Back in 2013 it was returning to US territory having been stationed in the Pacific within range of North Korea. The vessel was sold to congress on the basis that it could identify a golf ball in the air over San Francisco but has so far not been a major success, although it is intended to be able to identify incoming and then direct rockets towards them. I think that bizarrely it has used one of the several semi-submersible hulls built in Russia, others being bought and completed by Ocean Rig. So far, so the article I read states, $2.2 billion has been spent on it. It is probable that it will become part of a land based missile defence system in the future.

A Nuclear Submarine Collision.

Earlier this month the British nuclear submarine HMS Ambush collided with a merchant ship, either the Vemaoil XXI, the Vemaoil XXV or the Eco Friend. The submarine was submerged at the time. As part of one of the news releases, in which it was stated that the damage to the submarine was minor, and nothing to worry about, and that no-one had been injured, it was stated that it had been taking part in exercises in which ships and aircraft from the UK, US and France had been engaged in 10 days attempting to hone their ability to hunt submarines. This fairly simple statement begins to tell us just a bit about what might have been happening. We might assume that the Ambush was being the mouse in the war game and that it was being hunted by the ships and aircraft of the NATO nations. And at this point we should assume that there is quite a bit of competition. Can the mouse avoid the cats, are the cats sharp enough to overcome the tricks the mouse might play? And if this is true, what better way for a submarine to avoid its hunters than for it to hide under the hull of a merchant ship, either employing neutral buoyancy or lying on the seabed. The damage to the submarine appeared to be on the forefront of the conning tower which might indicate that the captain had misjudged the draught of the merchant ship, or the available water between the bottom of the hull and the seabed. Since the submarine is now berthed in Gibraltar harbour the Spanish government have asking for an explanation of the event, and actually I’m surprised that we have not heard anything from whichever of the ships was hit. I mean there must have been quite a bang.

The Ocean GreatWhite

The builders recently released information about the Ocean GreatWhite the latest rig about to join the Diamond Offshore fleet. It is very big, for a semi-submersible, but of the variety of details available what makes it particularly important? Obviously the deadweight is interesting at 67,000 tonnes, but to make it suitable for drilling in very deep water it is a DPIII rig, which means that it has sufficient redundancy for any single compartment to be lost, and for it to remain operational, using its thrusters to maintain station. It can drill to 35,000 feet which means that the weight of the drill string must be supported by the derrick at that depth, and it has a variable deck load of 7500 tonnes, so it can hold lots of equipment, pipes, chemicals and liquids at deck level, and importantly remain stable. Doubtless it can also move from operational to transit draught and the other way without having to get rid of any of the deck load. This is a basic capability which was not available to the very early semi-submersible designs. Back in the 1970s the support ships had to transport all the stuff off the decks back into port for the rig to be able to get up on the pontoons, and then once the move had been carried out they had to bring all the stuff out again. We can also assume that it is not going to suffer much from “growth” which is a factor usually taken into account to allow for modification, and in the end has resulted rigs which are unable to expose the tops of the pontoons to the air, and so become difficult to move. It has cranes which can lift 100 tonnes, one assumes with the big block and it is provided with accommodation for 180 people. So quite a beast then!

Shiphandling

At the recent Nautical Institute Annual Conference one of the presentations was about the time in 2012 when the Bibby Topaz lost position due to a number of co-incident faults in the DP system, and one of the divers failed to get back into the bell because his umbilical was caught round a protuberance on the subsea manifold on which they were working. The ship rapidly lost position and the diver’s umbilical snapped, and it took some time for the mate and the master to get the vessel back to a point that they could recover the man, who was lying unconscious on top of the subsea structure.

The video of the event was of 45 minutes duration and featured the recovered diver with his newly built house and his wife. While this was heart-warming it took a question to a manager of the operating company to get an idea of what had happened. I picked up the fact that it had apparently required the master and the mate to operate the controls because it was not possible for one man to do the whole job. Were they going to train their masters in ship handling, the manager was asked? Well, they were going to try.

Meanwhile at the conference, numbers of the presentations had variously discussed manual ship-handling, at least in part because of the resulting damage to ships and offshore installations when DP systems have failed. So there seems to be a need to promote ship-handling skills, but what to do? At the wash-up discussion I suggested to the panel that the Nautical Institute should take an action to positively promote manual handling training. The response was that it was part of their strategic plan.

Whether having an item in the strategic plan to be actioned by 2021 is sufficient is doubtful. Heavens – by 2021 there may be no-one who actually knows how to drive a ship left. We are a dying breed. Some operators do not allow ships to be operated in manual control within their 500 metre zone. Some ships do not have their controls positioned in such a way that they can all be operated at the same time (Apparently including the Bibby Topaz).

And it has also occurred to me that of the 170 odd people in the conference, only a few of those present would know how to drive a supply ship, so in a way this discussion is meaningless. What’s the difference? In an attempt to answer that question there follows an explanation of what might be involved.

The essential requirement of offshore ship handling is to maintain station within range of an offshore crane, so that cargo can be discharged and loaded and liquids and powders can be discharged by means of long hoses, The process has developed over a couple of generations of supply ship deck officers. Back in the early days the ships all tied up at offshore installations and in some areas of the world they still do. This only requires strong nerves and a technique for approaching the offshore object, although often the lack of capstans aft ensured some heart stopping moments.

But in the North Sea when it was too rough to tie up, but an urgent item of cargo was required, the installation would ask if they could “snatch” the lift, and so the master would attempt to get the ship under the crane and, if successful, the lift would be carried out before it drifted away. Later snatching became commonplace, and finally it became the usual means of working, incidentally turning the pipe carrier into the optimum PSV. The person driving would attempt to hold the ship in position by altering the thrust of the engines, the position of the rudders, and usually the power of the thrusters.

When this situation became the norm the joystick was added to the canon of equipment available to the driver, and really in order to operate it more easily an additional thruster was often added forward, and a couple of thrusters aft. This reduced the complexity of going sideways using the engines and rudders. But the joystick is an aide and so the driver should be able to maintain station using the individual controls.

So no-one is saying that to drive a ship manually is easy. It’s not even easy to explain. But I’ll attempt it using an example.  In the mid 1990s I was captain of a Halter Marine 180 footer, one of a number working in the Saudi oilfields, and I was assigned to the “drilling group” which supplied and assisted with the operation of a number jack-ups out there. There were other groups of ships, some supplying GOSPs (Gas Oil Separation Platforms)and some supplying the self-propelled liftboats which maintained the smaller platforms. I got a call one day from the barge control, saying that while they knew it was nothing to do with me, could I go and give one of the liftboats water. When I got there I understood the problem. The liftboat was elevated next to a conductor – a pipe sticking out of the sea – rather than being alongside a platform, all of which have a landing stage. And as it turned out none of the ships in its support group could “snatch’ water. They all expected to tie up at the landing stage.

So, it was a lovely day and I was able to determine that there was a slight current running, by looking at the legs of the liftboat, which I countered by crossing the engines – one ahead and one astern, and adjusting the rudders and the bowthruster. Once the position was stable I took down their hose and hovered about for an hour while our engine men pumped up the water.

All I had to do was keep the hose slack, and avoid running into the legs of the liftboat or – God forbid – the conductor. If I perceived that the ship was drifting astern I would knock the ahead throttle a fraction, and take a bit of rudder off, if ahead I would do the same with the astern engine. If I perceived that the ship was drifting down current I would add a bit of rudder and bowthrust. All of these actions were extremely gentle, otherwise I would have to take some counter action once in the required position.

So this was driving at the most basic level. I had been used to more sophisticated systems. Ulstein favoured rudder controls which allowed each to be operated separately and I preferred to keep the rudder on the astern engine amidships to increase the water flow to that propeller and only use the rudder on the ahead engine. And of course, the presence of one or more stern thrusters makes the use of the rudders less essential. And therefore if the ship is fitted with controllable pitch propellers it would be possible to use the main engines just for going ahead and astern.

So what about azimuthing propulsion? I can almost hear you ask. And as a second question, why do so many ships with podded propulsion crash into things. It seems to me, as an observer, that it is thought by mariners that ships with podded propulsion are more difficult to steer, and therefore they tend to use the autopilot or the joystick for doing nearly everything, and then sometimes they forget that they are using the autopilot. Check out the Big Orange XVIII at Ekofisk, a prime example.

Hence, driving a support vessel requires a thorough understanding of the forces to which the ship is being subjected and an understanding of the forces which the ship is capable of exerting. And if you question anyone who pays for simulator time you will find that it is used to exercise emergencies and as a simple teaching aide. No-one is going to give an individual the many hours of practice required to learn to drive as a reflex action. But obviously it can be done, and shipmasters and owners and charterers should bear in mind that their deck officers will all be keen to learn, so let them at it!

Fishing Boats 

If you are following the sales of second hand ships you might note that some offshore vessels are being used in some way to support fishing, and I think fish farming. One of the means by which they could be used is to help moor fish farms way out at sea, where the salmon parasite the sea lice cannot survive. The parasite enjoys the environment provided by the inland fish farms, and threatens the existence of wild salmon, and actually other farmed fish. An outbreak in Chile in 2007 resulted in whole pens of fish dying, and in one case the loss of a whole farm. Hence the Norwegians have initiated new regulations to curb the threat, just at a time when the producers are looking for ways to cash in on the high price of the product. They now have the idea of buying second hand merchant ships, available at bargain prices due to the oversupply in many areas of the market. An article in Bloomberg suggests that they would use container ships, or bulk carriers but surely tankers would be more suitable. It used to be quite common, in the days when tankers used to ballast their cargo tanks, for live fish to been seen swimming around, which to everybody’s surprise, had made it through the turbines of the cargo pumps.  

 
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