Offshore Crane Types Compared

The main types of offshore crane, what each is used for and how big they get, how the words on a crane specification fit together, and what each type means for heave compensation.

By Norwegian Dynamics Engineering · April 2026 · Updated September 2026 · 9 min read

Blender render of two offshore cranes side by side: a lattice-boom crane on the left and a knuckle-boom crane on the right, each with a load hanging from the hook.

In brief

Platforms mostly use lattice-boom pedestal cranes of tens of tonnes to serve supply vessels. Vessels favour compact knuckle-boom and telescopic cranes. Crane vessels carry heavy-lift revolving cranes of about 1,000 to 10,000 t, and jack-up installation vessels carry leg-encircling cranes of roughly 800 to over 3,000 t.
A crane specification describes three separate things: the boom (knuckle, straight or telescopic; lattice or box), how it is raised (ram or wire luffing) and what it stands on (pedestal, tub or a jack-up leg).
Cranes that lift to and from supply vessels at sea have a load chart for each significant wave height, with the dynamic factor built in. Heavy-lift, jack-up and subsea cranes are often rated with one design factor instead. Check what the chart includes before adding a factor.
An in-line heave compensator hangs below the hook, so it works with any crane type; the four interface checks are listed below.

Offshore cranes are named in several ways at once: by the shape of the boom, by how the boom is raised, by what the crane stands on, and by the job it does. A “knuckle-boom, ram-luffing pedestal crane” and a “subsea crane” can be the same machine. This page sorts the main types by where they work, then explains the labels.

The main types

Lattice-boom pedestal cranetens of tonnesThe platform crane: long reach, wire luffing, serves supply vessels
Knuckle-boom cranea few to several hundred tonnesFolds for stowage; the common vessel crane, often with active heave compensation (AHC)
Telescopic craneabout 1–30 tExtending boom sections; compact service and provision lifts
Heavy-lift revolving craneabout 1,000–10,000 tCrane vessels: topsides, jackets and foundations
Leg-encircling craneabout 800 to over 3,000 tSlews around a leg of a jack-up installation vessel
A-frametens to a few hundred tonnesLaunch and recovery over the stern: ROVs, trenchers, subsea structures

How they compare

Type	Where it works	Typical capacity	Typical lifts	Heave compensation
Lattice-boom pedestal crane	Fixed platforms; floating production units; some vessels	Tens of tonnes	Cargo to and from supply vessels, equipment, maintenance	On a fixed platform only the deck below heaves: a shock absorber such as POLARIS takes the snap at pick-up
Knuckle-boom crane	Supply, construction and service vessels; platforms	A few to several hundred tonnes	Deck handling; subsea construction with AHC	Subsea cranes often have AHC in the winch; where not, an in-line unit below the hook
Telescopic crane	Vessels and platforms	About 1–30 t	Provisions, spares, small equipment, over-side work	Rarely needed; for heavier over-side lifts into the water, a small in-line passive unit
Heavy-lift revolving crane	Crane vessels; the largest are semi-submersible	About 1,000–10,000 t per crane (20,000 t with two in tandem)	Topsides, jackets, foundations, heavy modules	Heavy in-line passive or adaptive passive units, for the splash zone and set-down
Leg-encircling crane	Jack-up installation vessels	Roughly 800 to over 3,000 t	Wind turbine components, foundations	Once jacked up, the crane does not heave: soft set-down, and the snap when lifting from a floating feeder barge
A-frame	Vessel sterns, some sides	Tens to a few hundred tonnes	ROVs, trenchers, ploughs, subsea structures	Launch and recovery through the splash zone: an AHC winch or an in-line passive unit

Capacities are rounded ranges from public crane and vessel specifications. A given crane’s certified load chart is the only authority for what it can lift.

Reading the labels on a crane specification

A specification describes three separate features. They combine freely: a knuckle boom is usually ram-luffed, a long lattice boom is usually wire-luffed, and both can stand on a pedestal.

Figure 1. The same three descriptors on two cranes. Left: a knuckle boom, raised by a luffing ram, with a second ram on the jib. Right: a straight lattice boom, raised by a luffing wire from a gantry. Both stand on a pedestal.

Descriptor	Options	What it changes
Boom geometry	Shape: knuckle (folding), straight or telescopic. Build: lattice truss or box section	Reach, stowage and working envelope. A knuckle boom folds to stow compactly and places loads close to the deck.
Luffing	Ram (hydraulic cylinder) or wire (luffing wire from a gantry)	How the boom angle is held. Rams suit compact booms; wire luffing suits long lattice booms.
Mounting	Pedestal (including king-post designs), tub, leg-encircling	How loads go into the structure, and the slewing range

Duty names sit on top of these. “Platform crane”, “subsea crane” and “heavy-lift crane” describe the job. A subsea crane, for example, is usually a knuckle-boom or lattice-boom crane with active heave compensation and a long wire. DNV-ST-0378 uses “platform crane” more narrowly, for lifts in harbour or within the unit; a crane serving supply vessels at sea is an offshore crane in its terms.

What crane type means for heave compensation

Seen from the load, the crane structure, the wire, the rigging and any compensator are springs in a chain above it. With suspended mass $m$ and overall stiffness $k$ , the lift has a natural period

T_n = 2\pi\sqrt{\frac{m}{k}}

The springs act in series, so the softest one dominates $k$ :

\frac{1}{k} = \frac{1}{k_{\text{crane}}} + \frac{1}{k_{\text{wire}}} + \frac{1}{k_{\text{rigging}}} + \frac{1}{k_{\text{comp}}}

A long subsea wire softens the chain and moves $T_n$ towards the wave periods, where the load can resonate. A passive compensator adds a much softer gas spring. With enough gas volume it moves the natural period well above the wave periods, and the load follows only a small part of the crane-tip motion. Sized too stiff, it can move the period into the wave band instead, so the new period is checked against the project sea states (see resonance avoidance). The principle is the same under any crane type. What changes with the type is where the heave comes from:

Crane on a floating vessel (knuckle-boom, heavy-lift, A-frame): the crane tip moves with the vessel, and the load is lowered through the splash zone and landed. This is the case for RIGEL and CYGNUS, or ANTARES where the load changes during the lift.
Crane on a fixed platform lifting from a supply vessel: the crane stands still and the deck moves. The peak comes at lift-off, when the slings snap tight; a shock absorber such as POLARIS takes it.
Jack-up vessel, once jacked up: the crane does not heave. Compensation is for setting loads down softly and, when components come from a floating feeder barge, for the snap at lift-off, as with a platform crane.

An in-line unit hangs below the hook and works on its own, independent of the crane’s controls. Four things still need checking for each crane:

Figure 2. An in-line unit under the hook block, and the four checks it needs on any crane.

Headroom. The unit adds its own length between the hook and the load. Check the lifting height at the working radius.
Hook interface. A shackle on the hook, or the unit’s top eye pinned into the block, which saves the upper shackle and its length.
Load range. The load in air and in water, including the splash zone, must sit within the unit’s stroke and rating.
Lift basis. In the rigging the unit is lifting equipment: its certificate and safe working load are checked against the lift’s design loads. See DNV-ST-N001.

Load charts and dynamic loads

An offshore crane’s load chart gives the safe working load at each radius. For lifts to and from vessels at sea, DNV-ST-0378 [8.2.4.1] and EN 13852-1 give it for each significant wave height, with the dynamic factor for that sea state built in; read the cell for the worst radius and the forecast sea state. Heavy-lift, jack-up and subsea cranes are often rated with a single design factor instead, and the lift analysis checks the lift’s DAF against it. Before adding a separate dynamic amplification factor, check what the chart already includes, so the same allowance is not counted twice. The crane load chart guide works through the reading and the dynamic factor, and the dynamic amplification factor guide covers the lift itself.

Frequently asked questions

What are the main types of offshore crane?

Lattice-boom pedestal cranes on platforms; knuckle-boom and telescopic cranes on vessels; heavy-lift revolving cranes on crane vessels, from about 1,000 to 10,000 t per crane; leg-encircling cranes on jack-up installation vessels; and A-frames for launch and recovery over the stern.

What is the difference between a knuckle-boom and a lattice-boom crane?

A knuckle boom folds at a joint, is usually raised by hydraulic rams and stows compactly, which suits vessels. A lattice boom is a long, light truss, usually raised by a luffing wire, which suits long reach and heavy lifts.

What is ram luffing?

Raising and lowering the boom with a hydraulic cylinder (ram). The alternative is wire luffing, where a luffing wire from a gantry holds the boom angle. Ram luffing suits compact booms; wire luffing suits long lattice booms.

What is a leg-encircling crane?

A crane on a jack-up installation vessel whose slewing bearing sits around one of the vessel’s legs, which saves deck space. Capacities run roughly from 800 to over 3,000 t, mainly for wind turbine and foundation installation.

Do offshore crane load charts include dynamic loads?

For cranes lifting to and from vessels at sea, yes: under DNV-ST-0378 and EN 13852-1 the chart gives the safe working load for each significant wave height, with the dynamic factor for that sea state built in. Heavy-lift, jack-up and subsea cranes are often rated with a single design factor instead, and the lift’s dynamic amplification factor is checked against it. Either way, check what the chart includes before adding a factor. See the crane load chart guide.

Can an in-line heave compensator be used with any crane?

In principle, yes: it hangs below the hook and works independently of the crane’s controls. For each crane, check the headroom, the hook interface, the load range in air and in water, and the certificate and safe working load against the lift’s design loads.

Basis and sources

DNV-ST-0378 (July 2019, amended October 2021): offshore cranes and load charts per significant wave height [8.2.4]; EN 13852-1:2025 General-purpose offshore cranes (floating cranes: EN 13852-2).
Typical capacities: public specifications of offshore cranes and crane vessels, rounded to ranges.
The natural period and series stiffness are standard single-degree-of-freedom results.