Cargo Gear – Cranes, Derricks and Cargo Winches

A crane does not fail at the moment the wire parts. It fails the morning nobody checked it.

Introduction

Cargo gear is not a collection of individual machines bolted to the deck. It is a system. The crane, its pedestal, its power supply, the wires, the blocks, the hooks, the limit switches, the operator, the banksman, the permit regime, the maintenance plan, and the register of lifting appliances all exist in dependency. Remove one element and the system does not degrade gracefully. It fails suddenly, usually under load, usually at the worst moment.

On geared bulk carriers, general cargo ships, heavy-lift vessels and offshore support craft, the ship’s own lifting appliances are the reason the vessel earns freight. They are also the reason surveyors return, the reason port state inspectors open the lifting appliance register before they open the logbook, and the reason a disproportionate number of serious maritime injuries involve cargo operations. Yet cargo gear maintenance is routinely deferred. Pre-use checks become a tick in a box. And the actual physics of SWL – a number that changes with radius, heel, trim and dynamic loading – is understood by fewer operators than anyone would care to admit.

This article treats shipboard cargo gear as the integrated system it is. It covers the principal types, the certification framework, what pre-use checks actually require, how SWL is misunderstood, and the recurring failures that investigation reports describe in almost identical language, voyage after voyage, year after year.

Contents

• 1. Cargo Gear as a System
• 2. Types: Electric Cranes, Hydraulic Cranes and Provision Cranes
• 3. Types: Derricks – Union Purchase, Swinging Derrick, Heavy Lift
• 4. Certification and the Register of Lifting Appliances
• 5. The Annual Thorough Examination
• 6. Pre-Use Checks: What They Actually Mean
• 7. SWL Understood Properly
• 8. The Operator, the Banksman and Visibility
• 9. Common Failures
• Closing Reality

1. Cargo Gear as a System

A ship’s crane or derrick is never just the steel structure visible from the quay. It is the electrical switchboard or hydraulic power pack that feeds it, the slew ring or pedestal bearing that supports it, the wire rope that transmits the load, the brake that holds it, the limit switch that should prevent two-blocking, the hook and its safety catch, and the operator who translates intent into motion. Downstream of the hook are the slings, shackles, nets and spreaders – all of which carry their own SWL and their own certification requirements.

Treat any of these as separate and the system concept collapses. A perfectly maintained crane with a corroded cargo runner is a hazard. A new wire on a crane with a bypassed overload trip is a hazard. A certified appliance operated by an untrained AB with no banksman is a hazard.

Systems do not fail in one place. They fail at the interface nobody thought about.

The chief officer who manages cargo gear must think in terms of the chain of dependency, not in terms of individual components. The planned maintenance system should reflect this. A task card that says “grease slew ring” but does not include inspection of the slew ring teeth for wear or cracking is maintenance theatre.

2. Types: Electric Cranes, Hydraulic Cranes and Provision Cranes

Electric deck cranes are the most common lifting appliance on modern geared bulk carriers and general cargo ships. They use an electric motor driving through a gearbox to the hoist drum, with separate motors for luffing and slewing. Control is typically from a cab mounted on the crane structure, though some are fitted with remote radio control. The advantage is simplicity of power supply – the ship’s main switchboard feeds the crane motor starters directly. The disadvantage is that electric cranes rely on electromagnetic brakes, and electromagnetic brakes rely on correct adjustment, clean friction surfaces and functioning release mechanisms. A brake that drags generates heat. A brake that slips drops loads.

Hydraulic cranes use one or more hydraulic pumps, driven electrically or by a dedicated diesel power pack, to operate hoist, luff and slew functions via hydraulic motors or cylinders. They are favoured on offshore supply vessels, smaller cargo ships, and as deck or provision cranes. Hydraulic systems offer smooth, proportional control and high power density. They also leak. Every hydraulic crane leaks. The question is whether the leak is within acceptable limits or whether it is draining the reservoir faster than anyone notices. Hydraulic oil on deck is a slip hazard. Hydraulic oil reaching the waterway is a pollution incident.

Provision cranes – the small cranes used for stores handling, typically rated at one to five tonnes – deserve special attention precisely because they receive so little. They are regarded as minor equipment. They are maintained last, checked least, and often operated by whoever happens to be nearby. Yet a one-tonne load falling from a provision crane will kill a person just as thoroughly as a thirty-tonne container falling from a main deck crane.

There is no such thing as “only a stores crane.”

3. Types: Derricks – Union Purchase, Swinging Derrick, Heavy Lift

Derricks predate cranes on cargo ships by a century. They are less common now but remain in service on older tonnage, training vessels, and in heavy-lift configurations where their load capacity can exceed anything a shipboard crane delivers.

The union purchase rig uses two derricks, one plumbed over the hold and one over the quay, with the cargo runner from each leading through blocks to cargo winches. The load is transferred between the two derrick heads by paying out on one runner while heaving on the other. It is a fast, efficient system for repetitive hook loads into and out of a single hold. It is also a system that imposes significant side loads on the derrick heads, the guys, and the mast or samson post. If the angle between the two runners at the common point exceeds approximately 120 degrees, the forces in each runner can exceed the weight of the load itself. This is not intuitive. It has caused failures.

The swinging derrick – a single derrick slewed by guys to spot the load – is slower but simpler. It imposes less complex loads but requires more careful guy handling and a competent winch driver who understands that slewing a loaded derrick by guy is not the same as slewing a crane. The loads in the guys change constantly with the derrick’s position and the ship’s motion.

Heavy-lift derricks – Stuelcken, Hallen, or bespoke designs – are specialist rigs capable of lifts from 60 tonnes to over 300 tonnes. Their rigging is complex, their operation requires detailed planning, and their maintenance is governed by manufacturer-specific procedures that cannot be generalised. Any vessel operating a heavy-lift derrick should have a detailed lifting operations manual aboard and crew trained specifically on that rig. Generic competence is not sufficient.

4. Certification and the Register of Lifting Appliances

Every lifting appliance and item of loose gear on board must be certified. The register of lifting appliances and cargo handling gear – typically maintained in the format required by ILO Convention 152 or the flag state equivalent – is the documentary proof that the gear has been tested, thoroughly examined, and found fit for use. It records the identification of each appliance, its SWL, the dates of testing and thorough examination, and the identity of the competent person who carried out the examination.

This register is not optional. It is not administrative. It is a legal document. If a crane drops a load and kills someone, the first thing the investigation opens is the register. If the last thorough examination is overdue, the master and the company have a problem that no amount of explanation will fix.

Loose gear – shackles, hooks, swivels, rings, chains, wire slings, webbing slings, spreader beams – must also be certified and recorded. The colour-coding systems used by many operators to indicate current certification status work only if expired gear is actually removed from service. A red-tagged sling found in the rigging locker is a latent failure waiting to enter the system.

A certificate with an expired date is not a certificate. It is evidence.

5. The Annual Thorough Examination

Under LOLER-equivalent regimes – whether the flag state applies the UK’s Lifting Operations and Lifting Equipment Regulations directly, or through classification society rules that mirror the same intent – every lifting appliance must undergo a thorough examination at intervals not exceeding twelve months, or in accordance with an examination scheme drawn up by a competent person.

A thorough examination is not a visual inspection. It is not a function test. It is a systematic, detailed examination by a competent person of every part of the appliance that could affect safety, including structural members, pins, bearings, wire ropes, brakes, limit switches, hydraulic cylinders, hoses, and electrical components. It may require partial disassembly. It will require the appliance to be operated under controlled conditions. It should result in a written report identifying defects, defects requiring immediate attention, and a statement of the appliance’s fitness for continued use.

The competent person must be genuinely competent. On many vessels, the classification society surveyor performs this role during the annual or intermediate survey. On others, a specialist shore-based inspector is engaged. What is not acceptable is a ship’s officer signing off the thorough examination on the basis of a walk-around and a function test, however experienced that officer may be. The regulations require independence and documented competence for a reason.

Where defects are found, the appliance must be taken out of service until rectified. Not after the current cargo operation. Not at the next port. Immediately.

6. Pre-Use Checks: What They Actually Mean

Before any lifting appliance is used, a set of pre-use checks must be completed. These are not the same as the annual thorough examination. They are operational checks, carried out by the operator or a designated competent person, intended to confirm that the appliance is safe to use on that day, in those conditions.

For hydraulic cranes, this means checking the hydraulic oil level in the reservoir, inspecting for visible leaks on hoses, cylinders and connections, and confirming that the oil temperature is within operating range after warm-up. A low reservoir level on a hydraulic crane is not a minor deficiency. It means oil has gone somewhere it should not be, and air may be somewhere it should not be.

Wire rope condition must be assessed visually on every use. The criteria are well established: broken wires per lay length, corrosion, kinking, birdcaging, reduction in diameter, distortion, and evidence of heat damage. A wire rope that “looks fine from the cab” may have a crushed section hidden under the first layer on the drum. The only way to check is to run the full working length out under observation.

Brake testing must be conducted with a load suspended at a low height. The load is hoisted, the hoist lever returned to neutral, and the brake must hold without creep. If the load creeps, the crane is unserviceable. There is no acceptable rate of creep.

Limit switches – the upper hoist limit, the lower limit, the luff limit, the slew limit where fitted – must be tested before the crane goes to work. Two-blocking, where the hook block is hoisted into the boom head sheave, is a catastrophic failure. The upper hoist limit switch exists solely to prevent it. If that switch does not work, the crane does not work.

Radio remote controls, where fitted, require a function test of every axis and the emergency stop. The emergency stop must kill all crane functions and apply all brakes. If it does not, the radio control unit is unserviceable.

A pre-use check that does not find the fault is worse than no check at all, because it generates false confidence.

7. SWL Understood Properly

SWL – Safe Working Load – is not a single number. On any luffing crane, SWL is a function of radius. The SWL plate on the crane shows the maximum permissible load at minimum radius. At maximum radius, the SWL may be a fraction of that figure. The load-radius curve, displayed either on a plate in the cab or in the crane’s operating manual, is the governing document. If the operator does not know the current radius, the operator does not know the SWL.

Many crane cabs are fitted with a radius indicator and a load moment indicator. These instruments must be calibrated and functional. A load moment indicator that has been switched off because it “keeps alarming” is a crane without an overload protection system. That crane is not fit for use.

SWL as marked assumes a static load on a stable platform. A ship is not a stable platform. The vessel’s motion – roll, pitch, heave – imposes dynamic loads on the crane that can significantly exceed the static weight of the cargo. A five-tonne lift on a vessel rolling five degrees in a swell is not a five-tonne load on the crane. The dynamic amplification factor depends on the period and amplitude of the ship’s motion, the length of the wire, and the stiffness of the crane structure. Classification society rules and individual crane manufacturers publish guidance on de-rating SWL for shipboard motion. That guidance must be applied.

Additionally, the direction of the lift relative to the ship’s centreline matters. A crane lifting over the ship’s side with the vessel heeled towards the load is working at a greater effective radius than the geometry suggests. The heel angle adds to the luffing angle. This is elementary trigonometry, but it is routinely ignored.

SWL is not a fixed number. It is a variable that changes with every degree of heel and every metre of radius.

8. The Operator, the Banksman and Visibility

A crane operator must be trained and assessed as competent for the specific type of crane being operated. Flag state and company requirements vary, but the principle is universal: operating a crane is a skilled task, not an incidental duty. Assigning an AB to a crane cab because everyone else is busy is how people die.

Visibility from the crane cab is limited by design. The boom obstructs the view forward. The house structure obstructs the view aft. The hatch coaming obstructs the view into the hold. In many lifting operations, the operator cannot see the load for a significant portion of the lift cycle. This is where the banksman becomes essential.

The banksman – the signaller on deck who directs the crane operator by hand signal or radio – is not a luxury. The banksman is the operator’s eyes when the load is out of the operator’s sight. Without a banksman, the operator is guessing. Guessing where a suspended load is, relative to structure and personnel, is not an operation. It is a gamble.

Hand signals must be standardised and agreed before the operation starts. Radio communication must be on a dedicated channel, clear, and using agreed terminology. The banksman must have a clear view of the load, the landing area, and any personnel in the danger zone. The banksman must have the authority to stop the lift. This authority must be real, not nominal. If the banksman calls stop and the operator continues, the system has failed at its most critical point.

9. Common Failures

Investigation reports into cargo gear incidents repeat the same findings with depressing regularity. The specific failures change; the underlying patterns do not.

Overload trips bypassed or ignored. The load moment indicator alarms. The operator cancels the alarm and continues. The overload trip activates. The electrician is called to reset it, or worse, to bridge it out. The next lift exceeds the structural capacity of the crane. This sequence appears in report after report. An overload trip that has been reset more than once in a single operation is not malfunctioning. The operation is exceeding the crane’s capacity, and someone is choosing to ignore the only system designed to prevent catastrophe.

Sea-fastening of cranes forgotten at departure. A crane that is not secured for sea is a pendulum. The slew brake holds the crane in position in calm conditions. In heavy weather, the dynamic forces on the jib can exceed the brake’s holding capacity. The crane slews uncontrolled, the jib strikes structure, and the resulting damage can extend well beyond the crane itself. Lashing the crane jib to the boom rest, engaging the slew lock pin, and confirming that the hook is secured are departure checks, not nice-to-haves. A crane jib swinging free in a North Atlantic storm is a wrecking ball.

Maintenance deferred because the crane is “only” used for stores. The provision crane at the after end of the accommodation is the neglected child of the deck maintenance plan. It lifts infrequently. It is small. It is out of the way. And when it fails, it fails with a load of provisions suspended over the quay, or over a crew member who was standing underneath because nobody rigged a barricade for a “small” lift. Every lifting appliance, regardless of size or frequency of use, requires the same standard of maintenance, examination, and pre-use checking. The regulations make no distinction between a 40-tonne deck crane and a 1-tonne provision crane. Neither should the ship.

Wire ropes run beyond discard criteria. Wire rope replacement is expensive. On a vessel with four cranes, a set of cargo runners is a significant budget item. There is perpetual pressure to extend wire life. The discard criteria in ISO 4309 exist because wire ropes fail progressively, and the visual criteria mark the point beyond which failure becomes unpredictable. Running wires beyond discard criteria is not economy. It is a bet placed with someone else’s life.

Function tests omitted after maintenance. A crane that has been worked on – brake adjusted, limit switch replaced, hydraulic hose changed – must be function-tested before it returns to service. The test must confirm that the maintenance has resolved the original defect and has not introduced a new one. A brake adjusted to be tighter may now fail to release cleanly. A limit switch wired in reverse will not trip when it should. Test every function. Test it under controlled conditions. Then release the crane to operations.

Closing Reality

Cargo gear is the productive heart of a geared vessel. It earns the freight. It is also the system most likely to kill someone on deck. The gap between these two facts is filled by maintenance, certification, competent operation, and honest pre-use checks – or it is filled by luck, and luck runs out.

The register of lifting appliances must be current. The annual thorough examination must be genuine. The pre-use checks must find the fault that exists, not confirm the readiness that is assumed. SWL must be understood as a variable, not a fixed number on a plate. The banksman must be there, visible, empowered, and listened to. And the provision crane at the aft end of the accommodation must receive exactly the same rigour as the main deck cranes, because the physics of a falling load does not care about the size of the crane it fell from.

A crane that works every day without incident is not proof of safety. It is proof that the failure has not happened yet.