Active heave compensation winch

An active heave compensation (AHC) winch measures vessel motion with a motion reference unit (MRU) and drives the winch to pay out and haul in exactly in time with the heave, so the load stays at a constant position relative to the seabed while the vessel rises and falls. Where a passive system reacts to load through a gas spring, an active winch references the seabed directly, cancelling far more of the motion and keeping the load steady enough for precise subsea work: landing equipment on the seabed, mating connectors, tool changes and controlled lifts through the splash zone.

What problem it solves

Vessel heave drives weather downtime and risks damaging the load and the equipment it lands on. Holding a load at constant depth through a seaway widens the workable weather window, protects deployed equipment and makes precise subsea operations possible in conditions that would otherwise stop work. It also keeps personnel away from snatch-load hazards by removing the sudden line movements that uncompensated lifting produces.

How we deliver it

• Control package, retrofit-capable – closed-loop, MRU-referenced control that upgrades a suitable existing hydraulic winch rather than requiring a new one, with the operator able to engage, disengage and set the compensation at any time.
• Designed with our heave-control family – shares the control, sensing and safety approach behind Active Heave Assist, Active Constant Tension and overload protection, so compensation, constant tension and load protection can be specified together.
• Failsafe and interlocked – protected against zero-load and inadvertent-activation conditions, with the load held safely if compensation is lost.

We size and configure the package to the winch, the load and the sea states it must work in and verify the control behaviour before it goes offshore. AHC suits constant-depth duties; where the priority is controlled weight-on-bit during drilling rather than holding depth, Active Heave Assist is the right tool.