Anchor Handling Tug Supply Vessels In The Offshore Industry

Origins of anchor vessels

The offshore industry consist of so many vessels for example the Anchor Handling Tug Supply vessels and Platform Supply vessels. These particular ships are changing, as a result, various demands accruing in the industry as well as the fuel cost and economic pressure. To ensure the traditional trends that were normally used are reversed, there is a need to combine the task into a ship which is multipurpose. The preparation of Anchoring Handling Tug supply vessel to operate in cold regions is sometimes becoming a problem. The operations and winterization have to attain certain requirements and crew needs, and in the case of the Arctic environment, the winterization of vessels is difficult. Some of the requirements of winterization for AHTS vessels to carry out their operations in cold weather include;

• Training of crews.
• Considering the crews.
• Personnel should have safety systems.
• Construction of hull.
• Coatings and materials.
• Vessel machinery and systems.
• Specific vessels needed for four vessels types.

Anchor Handling Tug Supply vessels are needed to carry out supply duties replenishing other vessels and drilling rigs in operational supplies field.  Anchor Handling Tug supply vessels are super strengthened and they are manufactured to sustain even in a difficult working condition of the sea by ensuring the crew safety, efficiency and comfort. Their efficient features make it possible for them to be used in sub-sea mooring operations in the Oil and Gas offshore fields (Brown, 2009, p. 433).  There are certain features entailed in Anchor Handling Tug Supply Vessels for example; AHTs vessels have superior bollard pull plus a higher engine rating making them necessary in anchor handling, the combination of multiple thrusters together with the twin screws CPP system used in fitting the AHTS vessels and the stowing of equipment wires heavy in weight and chains can be done due to a large amount of strengthened deck space of the accommodation areas (Buffa, 2016, p. 221).

The numerous duties showed simple articulate that AHTS vessels are in a position of performing traditional duties which were being undertaken by other vessels such as the Multi-purpose Supply Vessels, Emergency Rescue and Recovery Vessels or Diving Support Vessel and lastly the Platform Supply Vessels.  In the years to come, an oversupply of vessels will greatly affect the vessel owners and AHTS market is characterized by a large demand and supply imbalance as well as high standardization in the specification of vessels leading to ease in switching to alternatives. Compared to the past decades, the prices of vessels have stabilized at very low levels (Ambrose, 2009, p. 34)

Around Lake Catto in the year 1910 was when the water drilling operations began while in 1947, the ship development started on a serious notice immediately Kerr acquired the Land ship tank  (Skidmore, 2011, p. 332). Before the appearance of mobile drilling unit in 1950, the commissioning of Ebb Tide in 1955 took place to back up Mobile Offshore Drilling Unit owned by Mr. Charlie. (Taggart, 2011, p. 128).

Development of the Anchor Handling Tug Supply vessel

In 1956, the arrival of the three-legged jack-up was a major change which took place in the offshore industry and within that year; Scorpion was the first to enter the market. The supply chain vessels at the seal level were greatly minimized as a result of legs minimization. This made it very important to tie up the stern as well as dropping the anchor and this is known as Mediterranean moor. To ensure the AHTS has the ability to carry supplies to the platform, anchor handling operations and towing drilling units then there is need of ensuring it is designed with high horsepower. Nowadays, the use of higher horsepower vessels is increasing in deep water exploration thus making it handles heavier gear needed to operate at such depths.

The AHTS is increasing in usage since the offer a multi-utility facility thus they are demanded in a higher coverage area.  An increase in AHTS usage is relevant and makes a lot of sense because of the increase in oil drilling from the oceanic areas which is a regular operation.  The concept of AHTS is not something new though the knowledge is not common among various people who commonly engage in shipping and oil drilling activities.  The creation of AHTS by the marine world is very helpful since apart from aiding development in technology with smooth progress, they assist in the prevention of mishaps at the sea (Ambrose, 2015, p. 123)

Offshore Anchor Handling is an activity that can be termed as thrilling as well as tedious and terrifying and it more rewarding professionally point of view (Vergottis, 2008, p. 67). Testing of vessel handling proficiency of expert can be done by the anchor handling. Anchor Handling Tug Supply vessels are powerful ships that assist in deploying, recovering and shifting a subsea mooring pattern. The types of vessels mentioned above normally perform effectively with offshore installations. When carrying out anchor handling operations, heavy machines, as well as related tools, are repeatedly pushed to their extreme in a very hostile surrounding. Vessels are seriously damaged when they are working in a tough operating condition (Vergottis, 2008, p. 89).

By 1960, there were a number of operations carried out by the tidewater but there singly depending on carrying of cargo, daily supplies as well as drilling the tools being carried. A difficult operation involving deploying anchors and moving tags was carried out by tugs

During the 1960s, adding towards the deck forward end and A-frame aft permitted mooring of supply vessels. The recovery, as well as the deployment of the anchors, was achieved by A-frame differentiated the two kinds of water (sociology, 2008, p. 34). In around 1960s, North Sea started recording high amount of oil therefore making the two Americans, Mr. Louise and Cap to start using the American supply vessels as well as the tugs to service the operations. Some of those who own ships also decided to perform the operation followed by the tug owners from Dutch and Germany.  (Mcgrail, 2013, p. 532).

Evolution of offshore vessels

Anchor Handling Tug Supply vessels are majorly created to handle anchors for oil rigs, tow them to locations and use them in securing the rig in place. Operations related to supply transport and Emergency Response and Rescue Vessels are also performed by the AHTS vessels (Keit, 2014, p. 143). The designing of these vessels was mainly carried out to attain the harsh conditions of the North Sea and can carry out the tasks related to supply duties between the sites drilling is taking place and land bases. Fitting of AHTS vessels with winches for towing and anchor handling makes it different with the Platform Supply Vessels. They allow decking of anchors since they have open stern. The AHTS also can perform certain activities apart from towing and anchor handling, for example, the remotely operated underwater vehicle (ROV) services, rescue and safety services, as well as supply duties between the offshore installation and mainland (Kaiser, 2012, p. 56).

In 1965, the first supply vessel to enter the service was Smit-Lloyd 1 consisting of funnels located just after the pilot house. Ocean Inchcape (OIL) came in early 1970s and they were focusing in anchor handling with almost 2980 KW plus a deck area 372 m². However, the deck carrying capacity for the dry back bulk, for example, betonies, cement and barite, and drill water, fuel and potable water were retained. The versatile ship carried out a complete process and it entailed numerous activities, for example, hiring and assigning anchor handlers. Hiring as well as assigning anchor handlers were possible in this particular versatile ship and a complete process was fulfilled by this particular ship. Anchoring was taking place after the towing of the rig, followed by anchoring, and then supplying the drilling equipment from the shore (Hensen, 2016, p. 56).

The building of fixed platform in North Sea was done in 1970s and later it was fixed with the field jackets. Hamilton brothers went ahead in 1975 and came up with oil by converting a semi-permeable Trans-world 58. Introduction of supply ship took place and their construction as well as their operations was very easy.  (Dincer, 2011, p. 312).

Offshore Supply Association plus the Star Offshore decided to erect small ships having the ability to carry two lengths of pipe and this decision came after realizing the need for pipe carriers in the middle decade. A large ship was built in Norway which was in a position of carrying there lengths of pipes. The offshore installation process and working cargo were altered after the arrival of this particular ship in North Sea. This is because there were no mooring ropes provided to platform which were still under construction.  (Deen, 2009, p. 43).

Anchor dropping from the rig was the mainly accepted task for a working cargo and in order to reach the deck of the ship then the crane of mobile units is preferred. For the task to be handled two vessels with hydraulic deck were produced by the OIL and they can be moved immediately after clearing the stern area. A two large dedicated supply ships were introduced by Zapata which was an American company and the vessels were equipped in a similar manner. If the weather was too rough to tie up, and if the requirement for the cargo was urgent, the Master might be asked if he could “snatch” it (sociology, 2008, p. 345). This involved positioning the stern of the ship under the crane without tying up and holding it there for as long as it took for the crew to hook on the lift. In case ropes were not installed in platforms, then snatching of whole cargoes, and eventually for bulk cargoes to be discharged with long hoses (Ambrose, 2015, p. 211). Hence, with the advent of underwater side thrusters, instead of the ship lying stern-to the rig, it could be aligned alongside; making the whole deck available to the crane. The ship alignment made the pipe carriers to start carrying cargo and they were capable of handling cargo in large needed in certain locations. However, the industry had not abandoned the possibility that cargoes would also be carried on anchor-handlers, and several operators continued with the traditional technique of hiring a rig and anchor-handlers which would form support throughout the operation (Charles, 2012, p. 138).

In the late 1970s, there were numerous support vessels carrying out their duties on the seabed by operating through the delivery of divers to the site or with manipulators. These vessels include submarine support vessels and mini-submarine vessels. The submarine was deployed in the sea to operate in the seabed.  (Buffa, 2016, p. 12). Compared to the harbor tugs, Anchor Handling Tug supply vessels are super strengthened and they are manufactured to sustain even in a difficult working condition of the sea by ensuring the crew safety, efficiency and comfort. Their efficient features make it possible for them to be used in sub-sea mooring operations in the Oil and Gas offshore fields (Brown, 2009, p. 433).  There are certain features entailed in Anchor Handling Tug Supply Vessels as mentioned below;

• AHTs vessels have superior bollard pull plus a higher engine rating making them necessary in anchor handling.
• The combination of multiple thrusters together with the twin screws CPP system is used in fitting the AHTS vessels.
• The stowing of equipment wires heavy in weight and chains can be done due to a large amount of strengthened deck space of the accommodation areas.
• These particular vessels have chain lockers in large capacity thus enabling the sufficient amount of anchor chain to be stowed on board.
• To enhance both deep-water anchors handling plus towing is achieved due to extreme powerful multi-drum catering twin winches owned by Anchor Handling Tug Supply Vessels(Blank, 2011, p. 123).
• Various duties can be performed by the AHTS vessels since they are multipurpose and these duties include carrying fuel, water, and deck cargo in large quantity.

There are certain applications that are performed by the Anchor Handling Vessels and they include;

• They are used as multipurpose work boats in oil and gas offshore field.
• They take the role of rescuing and salvaging in case there are no readily available tugs.
• Anchor Handling Tugs assist in installing the SBM mooring and buoys.
• They are used for towing and anchor handling of newer offshore structures for example Tension leg(Bertram, 2010, p. 124).

The design of AHTs plays an important role in AHTS operations as well as maintenance. Optimization of AHTS simply relies on proper design thus making it suitable for providing services relating to oilfields in a competitive environment. Easy modification of AHTS makes it possible for the vessel to attain future demand and this simply communicates that flexibility is needed in the design as well as the planning stage. There also the need of altering the modes of operation, geographic theatres and regulations of Anchor Handling Tug Supply Vessels (Huitt, 2016, p. 321). To ensure the AHTS has the ability to carry supplies to the platform, anchor handling operations and towing drilling units then there is need of ensuring it is designed with high horsepower. Nowadays, the use of higher horsepower vessels is increasing in deep water exploration thus making it handles heavier gear needed to operate at such depths.

The construction of OSVs fleet is optimized by the fabrication of AHTS and the demand for AHTS is increasing now and again since it has certain advantages even the OSVs are lacking. The AHTS quantity and quality can meet the demand from the oilfield market and requirements from advanced offshore activities currently (Becky, 2015, p. 65).The performance and quality issues relating to AHTS can only be solved by ensuring fabrication is carried out which will enhance its lifetime performance as well as quality. The fabrication of AHTS is a hugely complex project with features such as heavy workload, long period of design and fabrication, wide operations and technology intensive. The building of Anchor Handling Tug Supply vessels needs to attain certain requirements such as the formability, strength and weld ability characteristics as well as toughness.

The AHTS is increasing in usage since the offer a multi-utility facility thus they are demanded in a higher coverage area.  An increase in AHTS usage is relevant and makes a lot of sense because of the increase in oil drilling from the oceanic areas which is a regular operation.  The concept of AHTS is not something new though the knowledge is not common among various people who commonly engage in shipping and oil drilling activities.  The creation of AHTS by the marine world is very helpful since apart from aiding development in technology with smooth progress, they assist in the prevention of mishaps at the sea (Ambrose, 2015, p. 123).

Anchor Handling Tug Supply vessels are an important feature of the offshore oil and gas industry carrying out various operations such as mooring, positioning and towing of drilling rigs as well as other marine equipment. They are equipped with specialized winches and powerful engines and their duties hey required to carry out may include;

• Deploying as well as retrieving of anchors.
• Towing/tugging rigs, vessels are pushes to location or assistance during docking.

The equipment used in Anchor Handling Tug Supply vessels need to meet these requirements of Classification Societies and the parties involved.  Anchor Handling Winch should be design for holding braking capacity and adequate dynamics to control a normal combination of loads. The towing winches are designed to permit the quick release of drums and lines in the emergency situations or operational situations.  Both the anchor handling line, as well as the towline, may be either fiber rope or steel wire.

Conclusion

A well- designed ship is due to collaboration, state art of equipment, innovation and experience. The maintenance of the design will enable the manufactures to achieve certain factors such as reliability, environmentally, safety and economy. The performance of the AHTS vessels is greatly influenced by certain factors, for example, the form. The form of the vessel influence the vessel operability and AHTS is designed with forecastle in the open deck, in the bow and in the stern like OSVs.  Vessels having certain features such as environmental friendly hull lines optimized for improved eco-drive in all weather conditions.  These type of vessels put into consideration certain things such as low consumption of fuel, good sea keeping abilities and adhere to Clean design requirements.

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