- Home
- Categories
- Moonpool Systems
- Moonpool Handling Systems
Marine & Station Keeping
Moonpool Handling Systems
Moonpool Handling Systems control loads as they pass through the moonpool and the splash zone below it. The Category covers BOP guidance frames and guide rails, cursor systems that run on moonpool wall rails, and moonpool launch and recovery systems for ROVs and subsea tools, with their winches, heave compensation, power units and controls.
How handling systems work
In the splash zone, waves and water moving up and down the moonpool push a suspended load sideways and can swing it into the hull. A guidance system holds the load on rails until it is below that zone. A BOP guidance frame steadies the BOP as it passes through the hull on the riser. A cursor is a frame that travels on rails down the moonpool wall, locks onto the load and releases it at depth. A moonpool launch and recovery system for an ROV combines a winch, an umbilical sheave, a cursor, rails and often its own small hatch.
Configurations
| Type | Load | Notes |
|---|---|---|
| BOP guidance | BOP and lower riser package | Guide arms or frames at hull level |
| Tool cursor | Subsea trees, tools, modules | Runs on wall rails to below the hull |
| ROV launch and recovery system | ROV and tether management system | Winch, cursor, umbilical, often heave compensated |
| Riser guidance | Riser joints at the rotary | Centralises riser in the moonpool |
MacGregor and NOV are well-known OEMs for moonpool handling packages.
Key specifications
| Parameter | Why it matters | Typical classes or units |
|---|---|---|
| SWL and dynamic factor | Must cover the load in sea state | tonnes (kips), stated sea state |
| Rail length and depth | How far below the hull the load is guided | m (ft) |
| Cursor or frame size | Envelope of the equipment it holds | m (ft) |
| Winch pull and wire size | For launch and recovery systems | kN (kips), mm (in) |
| Heave compensation | Reduces snatch loads | Active or passive |
| Drive | Power supply | Hydraulic or electric |
Standards and certification
- Launch and recovery systems and cursors that lift are certified under lifting appliance rules, such as DNV-ST-0378 or the ABS guide for certification of lifting appliances, and NORSOK R-002 in Norway.
- These rules set design loads including dynamic factors, require a proof load test after installation, and call for periodic thorough examination.
- Winch wire needs a certificate and is inspected and discarded to the rules and the maker's limits.
- ROV systems also follow IMCA guidance for remote systems and ROV operations.
Failure modes and inspection
- Rails wear, bend and corrode, worst below the waterline. Survey the rails in drydock or with divers or ROV video.
- Cursor latches and locks wear and seize. Function test them at full stroke.
- Rollers and guide shoes wear flat. Measure them against OEM limits.
- Winch brakes wear and wire degrades. Run a brake test and inspect the wire to the discard criteria.
- Hydraulic cylinders, hoses and power units leak. Check rods for scoring and take an oil sample for an ISO 4406 count.
- Heave compensation accumulators and sensors drift. Ask for the last function test and calibration.
- Interlocks with doors and carts fail or get bypassed. Test every interlock on the source rig if possible.
Documentation
- Lifting appliance certificate and the last proof load test.
- Thorough examination records.
- Winch wire certificate and inspection report.
- OEM service history and modification records.
- General arrangement and rail drawings.
- Interlock and control system drawings.
Integration
Cursor and guide rails attach to the moonpool walls. A used system usually needs new rails welded to your structure, so check the wall geometry and stiffening on your rig against the rail drawing early. Then check the power unit supply, the control panel location and the interlocks with your moonpool doors and carts. ROV launch systems also need umbilical routing, power and control links to the ROV control room.
Overhaul and the used, surplus or refurbished choice
An overhaul renews rollers, latches, seals and hoses, inspects the winch and brake, replaces the wire if needed and ends with a proof load test. Complete ROV launch and recovery packages are easier to reuse than guidance systems built into one hull. For the ROV side see ROV Launch and Support Equipment, and for the BOP see BOP Stacks.
FAQ
Frequently asked questions
What is a cursor system in a moonpool?
A cursor is a guide frame that runs on rails down the moonpool wall and holds a load steady through the splash zone. It stops the load swinging into the hull as waves move water in the moonpool. Below the splash zone, the cursor releases the load and returns to the surface.
Can a used ROV moonpool launch system be fitted to another rig?
Yes, if the moonpool is large enough and new rails can be fitted to its walls. Expect structural work for the rails, connections to power and the ROV control room, and a proof load test before certification. Complete packages with winch, cursor and controls are the easiest to move.
What records should come with a used moonpool handling system?
Ask for the lifting appliance certificate, the last proof load test and thorough examination, the winch wire certificate and the OEM service history. The rail and general arrangement drawings show whether the system fits your moonpool. Interlock drawings help plan the commissioning tests.
Does a moonpool launch system need heave compensation?
Heave compensation is not always required, but it reduces snatch loads on the wire and the load as the rig heaves. ROV systems working in rough water often use it. If the used system has it, ask for the last function test and sensor calibration.
Looking for moonpool handling systems?
Tell us what you need and we will find out what is available. We reply within one business day.