Anchor Handling Tug Supply (AHTS) vessels are specialised maritime vessels that support offshore operations, particularly in the oil and gas industry. Equipped for anchor handling, towing, and supply tasks, they are essential for the installation and maintenance of offshore oil rigs and production facilities.
AHTS vessels boast high towing capacity and powerful engines, enabling them to manage heavy equipment used to secure offshore platforms in challenging environments. Their tasks include anchor handling, towing, supply missions, and marine logistics, transporting fuel, water, and cargo to offshore platforms.
Key to their versatility, AHTS vessels are designed for operation in challenging weather conditions, with ice-class hulls for cold climates and enhanced stability in rough seas. The integration of dynamic positioning systems (DP) ensures
precision when handling anchors and performing critical offshore tasks.
AHTS vessels are crucial to the safe and efficient execution of offshore projects, reducing downtime and improving the logistics of marine operations. Their role in offshore oil and gas exploration, platform maintenance, and maritime towing solidifies their importance in the global energy sector.
With rising demands for offshore exploration and production, the need for advanced AHTS vessels continues to grow, making them a critical asset in maritime services.
Applications of AHTS Vessels
Anchor Handling: AHTS vessels are primarily used for placing and recovering anchors to moor offshore rigs and platforms. This function is crucial in ensuring that the platform remains securely anchored, even in adverse weather conditions.
Offshore Towing: These vessels are designed to tow offshore platforms, rigs, and barges from port to offshore locations, or to move them between locations as needed. Their high-powered engines allow them to tow large and heavy structures with ease.
Supply Missions: AHTS vessels are also used to transport various supplies (fuel, water, cargo) to offshore platforms, ensuring that operational activities remain uninterrupted. They often carry equipment and materials essential for daily operations on offshore sites.
Platform Maintenance Support: In addition to initial platform setup, AHTS vessels provide ongoing maintenance support, including towing and mooring line adjustments, ensuring platforms remain operational through their lifecycle.
Search and Rescue Operations: In emergency scenarios, AHTS vessels can be mobilised for search and rescue missions, owing to their stability, maneuverability, and offshore capability.
Key Features of AHTS Vessels
Powerful Towing Capacity: AHTS vessels are equipped with high-torque engines and large bollard pull capacities, which allow them to tow heavy structures such as drilling rigs, production platforms, and other offshore installations.
Dynamic Positioning (DP) Systems: Modern AHTS vessels are often equipped with Dynamic Positioning (DP) systems, which allow the vessel to maintain its position accurately without the need for anchors. This feature is essential for precise anchor handling and platform maintenance in challenging conditions.
Stabilized Hull Design: AHTS vessels are designed with a hull form that provides high stability in rough seas, ensuring that they can perform delicate tasks such as anchor handling or towing even in extreme weather conditions.
Ice-Class Capabilities: Many AHTS vessels are built with ice-class hulls to withstand operations in colder environments and icy waters, which are common in Arctic or sub-Arctic regions.
Large Deck Area: These vessels feature large deck spaces for carrying cargo, equipment, and materials needed for offshore operations, maximizing their versatility in marine logistics.
Heavy Lifting Capabilities: Some AHTS vessels come equipped with heavy-duty cranes and winches that allow them to handle large loads and assist with lifting operations on offshore rigs and platforms.
Enhanced Safety Features: Safety is paramount in offshore operations, so AHTS vessels are designed with advanced safety systems, including fire suppression systems, safety zones, and life-saving equipment for crew and personnel onboard.
Key Parameters of AHTS Vessels
Bollard Pull (BP): The bollard pull is a critical measure of a vessel's towing capacity, representing the maximum force the vessel can exert while stationary. AHTS vessels typically have a bollard pull ranging from 100 to 200 tons, depending on the size and design.
Length Overall (LOA): AHTS vessels vary in size, with typical lengths ranging from 60 meters (200 feet) to 90 meters (295 feet), although some larger vessels can be even longer. The length is an important factor for stability and cargo space.
Deck Area: The deck area is usually measured in square meters, with 500 to 1,500 m² being typical, allowing the vessel to carry a range of offshore equipment and supplies.
Fuel Capacity: AHTS vessels are designed to carry large volumes of fuel, typically between 500 to 1,500 cubic meters, to support long offshore missions. This allows them to travel extended distances without needing to return to port frequently.
Speed: The cruising speed of an AHTS vessel typically ranges from 12 to 16 knots, depending on the engine size, design, and operational needs.
Dynamic Positioning (DP) Class: Modern AHTS vessels are classified by their DP capabilities. The most common DP classes are DP1 (basic station-keeping), DP2 (redundant systems for more advanced station-keeping), and DP3 (full redundancy for critical operations).
Towing Capacity: The towing capacity of an AHTS vessel is crucial for moving large offshore structures. This is usually measured in tons of bollard pull, with some high-end vessels able to tow in excess of 200 tons.
Maximum Draught: The maximum draught, or the depth of the vessel below the waterline, varies depending on the vessel's size and design. For AHTS vessels, typical draughts are between 5 to 10 meters.
Gross Tonnage (GT): Gross tonnage reflects the overall volume of the vessel, with large AHTS vessels often reaching 3,000 to 10,000 GT.
