Anchor Handling Tug Supply (AHTS) vessels are mainly built to handle anchors for oil rig

Oil platform

An oil platform, also referred to as an offshore platform or, somewhat incorrectly, oil rig, is a lаrge structure with facilities to drill wells, to extract and process oil and natural gas, and to temporarily store product until it can be brought to shore for refining and marketing...

s, tow them to location, anchor them up and, in a few cases, serve as an Emergency Rescue and Recovery Vessel (ERRV).

AHTS vessels differ from Platform supply vessel

Platform supply vessel

A Platform supply vessel is a ship specially designed to supply offshore oil platforms. These ships range from 20 to 100 meters in length and accomplish a variety of tasks...

s (PSVs) in being fitted with winches for towing and anchor handling, having an open stern to allow the decking of anchors, and having more power to increase the bollard pull

Bollard pull

Bollard pull is a value that allows the comparison of the pulling force of watercraft, particularly tugboats. A mooring bollard may be used as a point of attachment for measuring the force, or pull of the craft.-Background:...

. The machinery is specifically designed for anchor handling operations. They also have arrangements for quick anchor release, which is operable from the bridge or other normally manned location in direct communication with the bridge. The reference load used in the design and testing of the towing winch is twice the static bollard pull.