What kind of work is done using Dynamic Positioning?
What started out as a technology designed to position drillships in deep water has trickled down through the offshore industry & can now be found installed on all types of vessels. It is being used today in capacities never imagined back when it was first invented.
In this series we will take a look at how the technology is being utilized & some examples of ships on which it is installed.
DP began with the drill ships so that is where we will start as well.
As explained in my Previous Article on gCaptain, the first vessel equipped with DP was the Eureka, owned by Shell. Although designed as a drill ship she ended up performing mostly coring operations. 10 years later the SEDCO 445 was delivered as the first purpose built DP drill ship. The 445 is still working in the field today, owned by Transocean & renamed the Deepwater Navigator.
What are the DPO’s duties?
A drillship is connected to the sea floor most of the time. The vessel needs to stay within a certain position radius to ensure that the angle on the drill string does not get too great.
The DPO pays close attention to the weather & prevailing conditions & ensure that the vessel stays on the minimum power heading when possible. When the vessel automatically adjusts her heading to this effect it is known as “weather vaning”.
She will be equipped with a class 3 DP system, due to the large potential for environmental damage should something go wrong.
In a Red Light situation where the vessel is unable to hold position or is driving off, the drill string may have to be disconnected remotely. This is a complex task, as the well needs to be shut, the landing string closed & pressure needs to be bled off before unlatching.
This could be potentially avoided if a quick thinking DPO sees the problem right when it occurs & is able to take steps to mitigate the severity.
PSV’s & AHTS
The workhorse of the offshore, these ships perform a variety of tasks, from setting or recovering anchors, to running all description of supplies between the beach & rigs or vessels offshore.
These vessels provide the drilling fluids, fuel & tools necessary for running the jobs offshore. In some cases they act as Hot Shots, delivering critical supplies needed to keep the job running.
In other cases they spend long hours Standing By, either waiting to receive a load or just to support as needed.
Supply boats will normally be equipped with Class 1 systems, as the primary use is station keeping. Much of the time spent on DP is just standing by in the field, waiting on the call. Although the requirements differ from company to company, it is generally required to be used when coming alongside another vessel for cargo transfers.
The DP console will be stationed close to the aft bridge, so you can look out over the working deck.
Many companies these days specify that operations with the potential for damage to the environment, such as transfering fuel or other fluids, be carried out on DP, making its installation mandatory.
Working on supply boats can be a good way to obtain DP time when trying to obtain your license, however as it is a class 1 vessel the ticket will be Limited & you will still require some time onboard a class 2 or 3 vessel to complete the Training Requirements.
Here is a clip of the M/V Seacor Cougar while on DP