AHVs are specialist vessels used for the pre-laying of anchors and mooring lines, and the tow-out and hook-up of floating offshore wind turbines.

What it costs

This is included in the anchor and mooring installation contract.

The typical day rate for a 200 t bollard pull AHV is about £50,000. Smaller AHVs have a typical day rate of between £20,000 and £30,000.

Who supplies them

Boskalis, Bourbon Offshore, Damen, DOF, Maersk, MMA offshore, Siem Offshore, SEACOR Marine, Solstaad Offshore and Vard Marine.

Anchor-handling vessel.
Anchor-handling vessel. Image courtesy of Vryhof. All rights reserved.

Key facts

The same vessels may be used for anchor and mooring pre-installation, and tow-out operations.

AHVs have sufficient deck space to carry between four to six anchors per trip, depending on the design of the anchors. AHVs are classed by their dynamic positioning or station keeping abilities and bollard pull capacity.

Large AHVs are characterised as follows:

  • Up to 25 m (breadth) by 95 m (length) and can operate at a speed up to 20 kn (transit speed)
  • Accommodation for a crew of up to 60
  • Maximum cargo capacity of 800 t
  • Minimum bollard pull of 200 t, and
  • Likely to be equipped with towing and anchor-handling winches, stern roller, knuckle boom cranes, towing and stopper pins.

For tow-out and hook-up operations the main towing AHV should have a bollard pull of 200 t. A vessel of similar bollard pull is required for installing drag embedment anchors. Two smaller AHVs usually support tow-out and hook-up operations. These vessels have a bollard pull capacity of between 50 to 100 t.

What’s in it

Guide to a Floating Offshore Wind Farm