ROV Launch and Support Equipment

ROV launch and support equipment moves a work class vehicle between deck and seabed. This category includes over-side A-frames and LARS cranes, moonpool cursor systems, umbilical winches and armoured lift umbilicals, tether management systems (TMS) and the hydraulic power units that drive them. Most of it is lifting equipment and is certified as such.

How launch and recovery works

The A-frame or crane lifts the vehicle and TMS off deck. A docking head, or snubber, latches the TMS to stop it swinging as it passes through the splash zone. On a moonpool system a cursor runs on guide rails and holds the package steady through the moonpool. The winch then pays out the lift umbilical, which carries power, fibre and the full load. A slip ring and fibre-optic rotary joint pass power and data across the turning drum.

At depth the TMS releases the vehicle on a neutrally buoyant tether. A garage TMS holds the vehicle in a cage. A top-hat TMS sits above the vehicle and latches onto it. Some winches add active or passive heave compensation to cut snatch loads in the umbilical.

Configurations

Over-side A-frame LARS, the most common layout on drilling units with deck space at the rail.
Moonpool LARS with a cursor, which allows launch in rougher weather and keeps the umbilical away from the hull.
Crane-based LARS, where a dedicated crane replaces the A-frame.
Integrated skids that carry the A-frame, winch and HPU together, against separate units placed for the deck layout.

Key specifications

Parameter	Why it matters	Typical units
SWL and dynamic factor	Must cover vehicle, TMS and umbilical weight in the stated sea state	t (lb), Hs in m
Umbilical breaking load and length	Sets lift capacity and depth reach	kN (lbf), m (ft)
Minimum bend radius	Sheaves smaller than it fatigue armour and fibres	mm (in)
Winch line pull and speed	Recovery time and lift margin	kN (lbf), m/min (ft/min)
Slip ring passes	Must carry every power phase and fibre	power and fibre pass count
TMS tether length and rating	Vehicle excursion and the weight it can park	m (ft), kg (lb)

Standards and certification

IMCA R 011 (also LR 011) sets out initial and periodic examination, testing and certification of ROV LARS by a competent person, and the maintenance that supports it.
DNV-ST-0378 is a common design and certification basis for LARS, and the ABS and Lloyd's Register lifting rules serve the same purpose. When a used unit changes owner or rig, the society reviews the design documentation and witnesses a load test before it certifies the unit under its rules.
National lifting regulations apply where the rig works, for example thorough examination under LOLER in UK waters.
The lift umbilical carries the maker's certificate for breaking load and electrical and optical test results.

Failure modes and inspection

On the A-frame or crane, look for pin and bushing wear, cracks at pivot and cylinder lugs, and cylinder seal leaks. Use magnetic particle testing on lugs and welds.
On the docking head, check the latch, rotation drive and damper for wear.
On the winch, check brake holding capacity, the level wind, drum flanges and the slip ring. Run a brake test and check insulation and optical loss across the rotary joint.
Along the umbilical, look for broken armour wires, birdcaging, corrosion and kinks. Test insulation resistance and conductor resistance, and check each fibre for attenuation with an OTDR.
On the TMS, check the tether winch, latch, sheaves and tether. Tether faults are a common cause of ROV downtime.

The inspection ends with a function test of the full launch and recovery cycle and, where certificates have lapsed, a witnessed load test.

Documentation

Design approval or certificate of conformity.
Last load test certificate and thorough examination report.
Register of loose lifting gear.
Umbilical certificate, with a log of cut-backs, re-terminations and length remaining.
Winch brake test records and NDT reports.
HPU maintenance records.

Integration

Check your deck strength and footprint where the LARS will sit. Any welding to the deck needs approval from the rig's class society. The HPU needs power from the rig, and the umbilical has to suit the vehicle's power and the control system's multiplexer. A moonpool system must fit the moonpool's size and guide rail layout. Sheave diameters must respect the umbilical's minimum bend radius.

Overhaul, used or unused surplus

An overhaul reseals cylinders, replaces worn pins and bushings, repeats NDT and relines the winch brake. The umbilical is replaced or re-terminated, and a load test closes the work with new certificates. A used A-frame or winch that passes this is good value. Treat a used umbilical as a wear item and price it into the deal. Unused surplus umbilicals still need checking for drum crush, end seal condition and storage exposure.

Well-known LARS makers include Kongsberg, Forum Energy Technologies (Dynacon), SMD and MacArtney.

Size launch gear to the work class ROV and TMS it will carry. Moonpool handling of other loads sits in moonpool handling systems.

FAQ

Frequently asked questions

Does a used ROV LARS need a new load test?

A used ROV LARS needs a new load test after installation on a new deck, after major repair, or once its certificates lapse. The certifying class society sets the test load and witnesses it. IMCA R 011 covers the examination and testing that follow over the unit's service life.

How do you check a used ROV umbilical?

Check a used ROV umbilical with insulation resistance and conductor resistance tests, an OTDR test on each fibre and a visual check of the armour along its full length. Ask for the cut-back and termination log and the length remaining. Broken or corroded armour wires reduce its breaking load.

Should I choose a top-hat or a garage TMS?

Choose a garage TMS if you want the vehicle protected in a cage through the splash zone and alongside the BOP. A top-hat TMS is lighter and smaller and sits above the vehicle. Your LARS capacity, deck space and the vehicle's dimensions usually decide which fits.

Can a LARS move to a different rig without new certification?

A LARS moved to a different rig needs a fresh examination and load test on its new foundation. If the new rig is classed by a different society, that society also reviews the design documentation before it certifies the unit. Plan the deck foundation approval at the same time.

Why does sheave diameter matter on an ROV umbilical?

Sheave diameter matters because bending the umbilical tighter than its minimum bend radius fatigues the armour wires and strains the optical fibres. Each pass over an undersized sheave shortens its life. Check every sheave in the LARS against the umbilical maker's limit before you pair them.

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