Which offshore crane type is most common?

The knuckle boom crane — standard on offshore platforms and supply vessels, with capacities from about 5 to 300+ tonnes. The articulating joint lets the boom fold for stowage and gives it some inherent compliance.

How does crane type affect heave compensation?

A stiffer boom transmits more vessel heave to the crane tip, raising the dynamic amplification factor — stiff-boom cranes on floating vessels benefit most from compensation. Wire rope length also matters: long runs act as springs, and resonance with the wave period must be avoided.

Does a heave compensator work with any crane type?

A passive compensator does: it installs in the wire path between hook and payload, independent of the crane's own systems, so RIGEL or ANTARES can be deployed on any crane. Active compensation is typically integrated into the crane winch instead.

Do crane load charts include dynamic loads?

No — load charts assume static conditions. DNV and NORSOK require dynamic loads to be accounted for in lift planning: the total hook load including DAF, rigging weight and any subsea forces must stay below the SWL at the planned radius. A compensator recovers usable capacity by shrinking the dynamic component.

Offshore cranes with different boom geometries silhouetted at dusk

Offshore crane types

Knuckle, stiff boom, ram luffing — the geometry decides how much of the sea reaches your hook.

Offshore Crane Types Compared

Q: What are the main types of offshore cranes?

Four categories by boom geometry and luffing mechanism: knuckle boom (articulating joint), stiff or fixed boom (straight, higher capacity and reach), ram luffing (boom angle set by a hydraulic ram), and pedestal cranes — a mounting category that can carry any boom type with 360° rotation.

Main Types of Offshore Cranes

Offshore cranes fall into several categories based on their boom geometry and luffing mechanism:

Practical application: For practical application of this topic, see POLARIS crane shock absorber and product / system design.

Knuckle boom cranes — the most common type on offshore platforms and supply vessels. The boom has an articulating joint (knuckle) that allows the boom to fold for stowage. Capacities from 5 to 300+ tonnes. Manufacturers include Liebherr, NOV (National Oilwell Varco), and Palfinger.
Stiff boom (fixed boom) cranes — a straight boom without articulation. Typically higher capacity and longer reach than knuckle boom cranes. Used for heavy lifts and construction operations. Common on semi-submersible crane vessels (SSCVs).
Ram luffing cranes — the boom angle is controlled by a hydraulic ram rather than a wire rope. Provides precise load positioning and is common on jack-up rigs and drilling platforms. Favell, SMST, and Huisman manufacture these.
Pedestal cranes — a general category for cranes mounted on a fixed pedestal, which can use any boom type. The pedestal allows full 360° rotation.

Type	Boom / luffing	Capacity & use	Typically seen on	Compensation note
Knuckle boom	Articulating joint; folds for stowage	5 – 300+ t	Platforms, supply vessels	Some inherent compliance at the knuckle
Stiff / fixed boom	Straight boom, no articulation	Higher capacity, longer reach; heavy lift & construction	SSCVs	Stiffest path — gains most from compensation afloat
Ram luffing	Boom angle set by hydraulic ram	Precise load positioning	Jack-ups, drilling platforms	Precision handling; dynamics still per sea state
Pedestal	Any boom type on a 360° pedestal	General category	Fixed installations	Mounting, not geometry — boom type governs

How Crane Type Affects Heave Compensation

The crane type influences heave compensation requirements in several ways:

Boom stiffness: A stiffer boom transmits more of the vessel heave to the crane tip, increasing the dynamic amplification factor. Stiff boom cranes on floating vessels generally benefit more from heave compensation than knuckle boom cranes, which have some inherent compliance at the knuckle joint.

Wire rope length: Longer wire rope runs act as springs, changing the natural frequency of the lifting system. Resonance between wave period and the system natural period must be avoided — a heave compensator shifts the natural period away from typical wave periods.

Integration: Active heave compensation (AHC) is typically integrated into the crane winch drum. Passive heave compensation (PHC) is installed in the wire rope path between the crane hook and the payload — this makes PHC systems crane-independent and suitable for any crane type.

A RIGEL or ANTARES compensator can be deployed on any crane because it sits below the hook, independent of the crane own systems.

Active (AHC)Integrated into the crane winch drum — a property of the crane

Passive (PHC)Installed in the wire path between hook and payload — crane-independent

Any crane, any boomRIGEL and ANTARES deploy below the hook, independent of the crane’s own systems

Crane Load Charts and Dynamic Loads

Every offshore crane has a load chart that specifies maximum safe working load (SWL) as a function of boom angle and radius. The load chart assumes static conditions — actual dynamic loads during a lift can exceed the chart values due to vessel motions.

DNV and NORSOK standards require that dynamic loads be accounted for in lift planning. The total hook load must remain below the crane SWL at the planned radius, including the dynamic amplification factor, rigging weight, and any subsea forces (drag and added mass).

A heave compensator effectively increases the usable crane capacity for a given sea state by reducing the dynamic component of the load.

Offshore crane types — frequently asked

What are the main types of offshore cranes?

Knuckle boom (articulating joint), stiff/fixed boom (straight, higher capacity and reach), ram luffing (hydraulic ram sets the boom angle) and pedestal cranes — a mounting category that can carry any boom type through 360°.

Which type is most common?

The knuckle boom crane, standard on platforms and supply vessels with capacities from about 5 to 300+ tonnes. The knuckle lets the boom fold for stowage and adds a little compliance.

How does the crane type affect heave compensation?

Boom stiffness sets how much vessel heave reaches the crane tip — a stiff boom afloat benefits most from compensation. Long wire runs act as springs, so the system natural period must stay clear of the wave period; a compensator shifts it away.

Can I use a heave compensator on my existing crane?

Yes, if it is a passive unit: PHCs sit in the wire path below the hook, independent of the crane’s systems — RIGEL or ANTARES deploy on any crane type. Active compensation is normally built into the winch instead.

Do load charts already include dynamic loads?

No — charts assume static conditions, and DNV/NORSOK require the dynamic loads to be added in planning: DAF, rigging weight and subsea forces must fit under the SWL at radius. The crane load chart page runs the numbers.

Related on Norwegian Dynamics

Crane Load Chart — Velocity formula, DAF derating, worked example.
DNV Standards for Offshore Lifting — ST-0378, ST-N001, RP-N103 and how they apply to compensators.
Heave Compensator Selection — Choose between PHC, APHC and AHC for your envelope.

Working on a lift that needs this?

Compensators sit below the hook — independent of the crane. If you have a crane and a problem load case, we can fit a solution.