Offshore Crane
An offshore crane lifts and lowers loads while the vessel itself is moving under wave action, using active or passive heave compensation to hold the load steady relative to a fixed platform or another vessel, which a standard deck crane has no way of doing.
What to check on an Offshore Crane.
11 models from Huisman in Offshore Crane. Below: the full model list.
What sets an offshore crane apart
A general cargo crane lifts and lowers a load on a stationary or slowly rolling ship, with the operator judging timing against the ship's own motion. An offshore crane routinely has to land a load on, or lift it from, a structure that is not moving with the ship at all: a fixed platform, another vessel, or the seabed. Vessel heave, roll and pitch mean the crane tip is constantly changing position relative to the load's destination. Offshore cranes handle this with active or passive heave compensation, letting the winch pay out or take in wire to hold the load at a near-constant position, or under near-constant tension, regardless of the vessel's motion.
Legend
- boom-tip sheave
- boom
- hoist wire
- active heave compensator
- operator cab
- luffing cylinder
- pedestal & house
- winch drum (in house)
- slewing ring
- hook block with load
- ship's deck
Main components
Pedestal and slew system
Fixed base and slewing ring carrying the full crane, with hydraulic or electric slew drives; on larger offshore cranes the pedestal is a significant structural item engineered into the ship's hull.
Boom and luffing system
Knuckle-boom or lattice-boom designs are both used; knuckle booms fold compactly for stowage and give better reach control close to the vessel, lattice booms give greater reach and capacity at longer radius.
Read the full guide
Main and auxiliary winch
The main winch carries the working load; the heave compensation system, whether active and constantly driven by the control system, or passive and reacting to line tension, sits in or alongside this winch.
Motion reference unit
Feeds real-time vessel motion data to the crane's control system on active heave-compensated cranes, so the winch can counteract heave in near real time rather than reacting after the fact.
Selection and sizing
- Safe working load at the required radius, read from the crane's full load chart, not a single headline lifting capacity figure.
- Heave compensation performance: stroke length and response time against the sea states the vessel is expected to operate in.
- Duty class and design factor appropriate to the lift type: cargo transfer, subsea, or personnel transfer, which carry different safety factors.
- Deck footprint, pedestal strength requirement and reach against the vessel's actual operating envelope.
Regulations and class
Class societies certify offshore cranes against their own lifting appliance rules, which set design factors, proof-load and periodic test requirements distinct from cargo gear rules. Cranes used for personnel transfer carry additional certification and are subject to stricter design factors and independent wire rope condition monitoring. Periodic thorough examination and load testing intervals are set by class and enforced through the vessel's safety management system.
Typical faults
| Fault | Cause | Consequence |
|---|---|---|
| Heave compensation lag | Motion reference unit miscalibrated or control tuning not matched to the actual sea state | Load impact or snatch loading at the point of transfer |
| Wire rope degradation | Repeated snatch loading and fleet angle issues on the compensated winch | Accelerated fatigue, risk of rope failure under load |
| Slew or luff drift under load | Hydraulic system leakage or wear in holding valves | Uncontrolled load movement, particularly hazardous during personnel transfer |
| Overload trip in a following sea | Load chart used without correcting for dynamic amplification from vessel motion | Emergency stop mid-lift, or exceeding the crane's rated capacity |
What to look for in a supplier
- Class type approval for the specific crane model and, separately, for its heave compensation system.
- Documented compensation performance tested against real sea-state data, not simulation alone.
- Track record with the specific transfer type intended, since certification and safety case differ between cargo, subsea and personnel transfer.
- Remote diagnostics and a service network reachable at the vessel's actual operating area.
Treat the crane's load chart as a starting point, not the answer, in any real sea state; dynamic amplification from vessel motion can exceed the static safe working load well before the operator sees a warning.
Models in this type.
The best-documented model of each manufacturer first, then the next — 11 of 11 models in Offshore Crane. Every row links to full specifications, documents and service notes.
Manufacturers.
All 17 manufacturers with models of Offshore Crane. Names with a manufacturer page open it; the others open a search across the full library.
All manufacturers in the libraryAlso in Deck Cranes.
The other equipment types in this category.
Write to us about this model — the answer comes by e-mail.
Name the make and the model and what the job is: a spare, a service call, a second opinion on a data sheet. We answer by e-mail.
No details at hand? A photo of the rating plate or the part is enough — simply attach it to the request.
Questions that come up with this equipment.
Is Offshore Crane data free?
Yes. Every model page, every guide and every datasheet for this type is readable without an account. An account adds saved searches and requests, nothing is taken away.
My model is missing — what now?
Send us the nameplate. We identify it by hand, add it to the library, and if you need a part or a service, the request is already on our desk.
Can you source a Offshore Crane part?
Yes. Tell us the manufacturer, the model and what you need — a person reads every request and replies by e-mail.