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Moon Pool deployments from RSV Nuyina

Deploying equipment over the side or stern of the ship works well in the open ocean and in good weather. But when the weather is particularly rough, or the ship is in sea ice, some research has to stop. But not anymore.

The moon pool is a 13 metre vertical shaft, four metres square, which runs from the science deck, through the ship’s hull, to the open ocean. When its top and bottom hatches are opened the moon pool allows the deployment of equipment such as CTDs (conductivity, temperature and depth instruments), nets, underwater vehicles and other instruments, within the relative comfort and protection of the ship.

Check out the video below to see how it works.

CTDs are the workhorses of oceanography and are regularly deployed from the icebreaker through a side door or the moon pool. These metal rosettes contain up to 36 12-litre plastic bottles and are used to collect water samples at different depths, up to 6,500 metres. The rosette is lowered by a cable to the required depth – usually to the bottom. As the rosette descends and ascends over a few hours, a remotely triggered device allows the water bottles to be closed selectively, so that samples of water are collected at different depths. These water samples are then analysed to provide oceanographers with information about the physical and chemical properties of different water masses.

CTD Hangar

The CTD Hangar on Deck 4 provides 133 m2 of enclosed and heated deck space, giving flexibility to scentists for staging, operating, and deploying a range of scientific equipment.

The Moon Pool is for the deployment of scientific equipment when the ship is in ice or heavy weather. It is a 4 m x 4 m opening through to the bottom of the hull with two hydraulic upward opening doors at the bottom to prevent ice ingestion and two downward opening doors at the Deck 4 level. Equipment can be lowered through the Moon Pool using either the CTD winch or the General Purpose winch. The winch wire runs through a Cursor that keeps the wire centred in the moon pool trunking. The Cursor is track mounted and has a dedicated handling system to allow it to be lowered to the bottom of the moon pool, where it remains while the sampling equipment is deployed.

Winches

  • General Purpose Winch: 8,000 m x 12.0 mm steel wire rope; 78.5 kN Safe Working Load (SWL)
  • CTD Winches: 2 x 8,300 m x 11.43 mm Electro-Optical-Mechanical (EOM) cable; 68.7 kN SWL

CTD Deployment System

  • CTD Crane: telescopic overhead tilting crane with CTD docking head
  • Maximum lifting capacities:
    • Cast/towing position = 6 T SWL
    • Deployment/recovery position = 3 T SWL
    • ROV handling = 2.5 T SWL
    • Outreach = 4 T SWL
  • CTD Door: Side opening hydraulically operated; door shut when CTD has been deployed; top section upward outboard opening, remains open for crane access when CTD is deployed
  • Wire Washers: system is fitted with wire washers and driers
A large cylinder containing many capsules is lowered into a pool.
Winch wires run through a track mounted cursor for moon pool deployments. This guides equipment (like this CTD rosette) safely through the 13 metre shaft during deployment and retrieval. Photo: Pete Harmsen
Moon pool
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