AHA™ – Active Heave Assist (with AWOB™)

AHA converts an existing passive heave-compensation system into an actively assisted one, holding the drill bit stable relative to the seabed to within less than 10 cm, even in challenging conditions. Conventional active heave compensation holds position, but geotechnical drilling needs controlled advance. AHA lets the driller set a target weight-on-bit and a maximum feed rate and actively manages drill-string movement to maintain controlled progress. This is AWOB (Automatic Weight-On-Bit). It’s particularly effective in soft, layered or fractured ground: it prevents rapid punch-through, reduces the risk of blocking off and allows controlled descent where conventional weight-on-bit control isn’t possible. Multiple failsafes and an intuitive control panel let the driller choose the level of automation and override it at any time, at 0%, the system behaves exactly as a conventional passive system. AHA retrofits to a vessel’s existing passive system with minimal disruption to a normal mobilisation, a plug-and-play, roughly three-day installation that uses the existing HPU power and a driller-oriented interface with a short learning curve.

A world first, proven in service. AHA is the world’s first conversion of a passive heave-compensation system to active heave assist on a geotechnical drilling rig, a genuine piece of in-house intellectual property, developed and proven on a working vessel rather than in theory. It has been deployed on a commercial deep-water campaign over rocky, uneven seabed where jack-up barges and seabed frames could not be used, more than a kilometre below the surface, enabling advanced downhole logging that demanded precise bottom-hole-assembly position control. Development continues with AWOB and auto-core-run (ACR) control to push performance further across seabed conditions. AHA and AWOB also apply to large-diameter marine drilling and construction, for example, the installation of floating offshore wind (FLOW) foundations.

AWOB – Automatic Weight-on-Bit Control

AWOB (Automatic Weight-on-Bit) is the control layer AHA makes possible: with the load held steady relative to the seabed, the operator sets a target weight-on-bit and a maximum feed rate and the system actively manages the string or line to hold it. It needs AHA underneath it, you cannot control weight-on-bit precisely without first controlling position against the heave.

While AWOB was developed for geotechnical drilling, protecting cores and preventing punch-through in soft, layered ground, the same controlled-force-at-depth capability applies far more widely: large-diameter drilling (holding controlled weight-on-bit on a big bit), marine construction and pile installation, and launch-and-recovery, deployment and equipment recovery, where the same control lands an object softly on the seabed or breaks it back out under controlled load. Wherever a load has to be set down, advanced or recovered at a controlled force through vessel motion, AWOB-on-AHA is the tool.

Where it fits

AHA is the active layer of our heave-control family. It assists an existing passive heave-compensation system rather than replacing it and sits alongside our constant-tension winch control (ACT) and overload protection systems (OLPS). Together they cover the full span of heave-compensated, draw-works and line-tensioner duties, new-build or retrofit.