During the CS Tyco Durable’s laying programme, she will have to launch the four branching units (“BUs”) that will allow PIPE International to expand the system. This sounds relatively easy but the logistics are fairly complicated. A BU has three legs: Trunk, A1 & A2. Therefore it has 3 cables that need to be managed. This means that it cannot leave via the Linear Cable Engine (“LCE“) which can only handle a cable in a straight line.
And so starts a process of swapping the cable from the LCE to the Cable Drums (pictured) and from there controlling the payout of all three cables to ensure that the BU doesn’t twist as it is being deployed. The three cables need to land in the correct orientation or you will end up with crossed legs.
The whole process takes several hours and includes a few stops and starts and winding cable on and off the Cable Drums as the BU passes down the ship. Once it gets to the end of the highway it has to be transferred out on to a trolley for its trip along the aft deck. The 10T crane is also called in at this point to help with the manoeuvrers. With the cables no longer on the drum engines the crew apply a series of stopper and chains to take the tension and stop the BU making a bolt for the seabed too quickly. At each step of the process, the stoppers are moved down the deck to keep everything safe and under control.
Once the trunk leg of the BU (which is always the last to leave) is overboarded, a hatch opens in the rear wall of the Highway to allow the cable to be transferred back to the LCE. With this done, everyone prepares to continue the main cable laying.
Daniel - not sure that map is terribly accurate. Suggest instead: http://www.sailwx.info/shiptra...call=V7DI8
Durable real time tracking http://aprs.fi/?call=538001647 most vessels submit gps co-ordinates via aprs when they are within range of a ham antenna