4.0 Additional oceanographic measurements

Pre- Launch Procedure:

    • Lab to notify Bridge of the following:
      • Scheduled deployment time at least 15 minutes in advance.
      • Desired location to position the ship.
      • Request Winch Operator.

    • WOCE Personnel
      • Remove Triton X wash bottle.
      • Turn on pinger if it is a deep cast.
      • Check for removal / installation of fluorometer. If the fluorometer is removed, ensure the high-pressure dummy plug is installed on the CTD.
      • Check for loose gear, cables, etc. on the rosette.

    • Deck Leader
      • Turn on lights if necessary.
      • Verify recovery area is clear of all loose and extraneous gear.
      • Stage boat hook for easy access should it be necessary to use it.
      • Remove safety netting; stow forward out of the way by hooking it on the railing cleat.

    • Tag Line Personnel
      • Remove tie downs.
      • Stage tag lines through the rosette's fairleads (see diagram).

Launch Procedure:

    The Deck Leader takes up the wire and puts tension on it by pulling horizontally on the termination. The Deck Leader then signals to the Winch Operator to take up the slack in the wire. When the Deck Leader releases the termination from his grip, it is a signal for the Winch Operator to stop.

    All hands stand by for launch clearance from the Bridge and from the Lab. When the Winch Operator receives the all-clear from the Lab and the Bridge, he then informs the Deck Leader that the deployment may begin.

    The Deck Leader verifies that the launch crew is ready. When ready, the Deck Leader signals to the Winch Operator to begin deployment.

    The Winch Operator deploys the CTD package by moving the boom out. The initial extension of the boom lifts the package from the deck and moves it outboard. This requires some skill in manipulating the boom and the winch simultaneously. From the Winch Operator's perspective, launching and recovery is easier if the operation can be accomplished without stopping. This is a situation dependent on sea state conditions where coordination and timing are required to adjust the winch and boom controls. Once the rate of the boom or winch is fixed, the operator can then adjust the other axis (winch or boom) for a smooth, continuous, operation.

    The Winch Operator must be careful to keep the bottom of the package within 6 inches of the deck to protect the mechanical termination from damage. It is the Deck Leader's responsibility to observe and guide the Winch Operator. If the CTD package is lifted too high off the deck the termination can be pulled over the sheave or the cable grip may be pried off the cable by getting caught on the cheeks of the sheave, thus weakening the mechanical termination.

    While the package is being deployed, the tag lines are kept somewhat taught, depending on the situation and sea state. The rosette package should be somewhat restrained such that the package leans outboard due to the tag lines keeping tension while the boom is being deployed. Once the boom is fully deployed, the bitter end of the tag lines should be allowed to be paid out, retaining some tension on the line, until the bitter end is reached. The bitter end is then allowed to free fall into the sea, clear of the rosette package. The tag line is then retrieved while the package continues to be lowered into sea. Due to the high freeboard from where the CTD is launched, it is important to minimize the time the package is in the air where the package may gain momentum to swing and perhaps hit the ship's hull.

    It is important to note that the bitter end of the tag lines should be deployed clear of the rosette package in such a mannner as to prevent the lines from getting tangled with each other, getting caught in the rosette package, or coming into contact with the sensors.

    The Deck Leader informs the Winch Operator when the package is in the water. The Winch Operator then continues deployment of the package to a depth of 10 decibars to prime the CTD plumbing. Meanwhile, the Deck Leader secures the safety net and the Tag Line Personnel neatly flake the tag lines on deck in preparation for the recovery.

    The CTD package remains at 10 decibars until the pumps turn on and prime the plumbing system. When the Lab's Console Operator is satisfied that the CTD system is ready and operating correctly, the Lab will inform the Winch Operator to bring the package to the surface to begin the down-cast.

    The Winch Operator, upon confirmation from the Lab, will bring the package to the surface at a maximum rate of 20 meters per minute. Since the Winch Operator cannot see the package at the surface, the Deck Leader watches the package and surrounding seas to determine the optimum point at which to stop the package at the surface. When the Deck Leader signals to the Winch Operator that the package is at the surface, the Winch Operator should immediately deploy the package to its target depth.

    Our objective is to bring the package's instruments as close to the surface while minimizing the time at the surface where the possibility of losing the plumbing's priming may occur due to swells or rolling of the ship.

Pre-Recovery Procedure:

    • Deck Leader: (To be accomplished well before the CTD is at the surface)
      • Notify team members to assemble on deck for recovery.
      • Remove safety netting; stow forward out of the way by hooking it on the railing cleat.
      • Turn on lights if necessary.
      • Verify recovery area is clear of all loose and extraneous gear.

    • Tag Line Personnel
      • Stage pole hooks.
      • Stage tag lines for retrieval by flaking the lines neatly on deck.

    • Lab
      • Notify the Deck Leader and the Winch Operator when ready to recover the CTD.

    • Winch Operator
      • Request clearance from the Bridge to recover the CTD.

    • Third Tag Line Person (discretionary during rough weather)
      • Man the pole hook, working as a team with the Aft Tag Line Person.
      • Leave the recovery area, with the pole, once the hook is secured to the rosette.
      • The Aft Tag Line Person, in this case, will focus on tensioning the tag line.

Recovery Procedure:

Towards the end of the CTD cast, the Lab Operator notifies the Deck Leader to prepare for the recovery of the CTD. The Deck Leader notifies other team members to assemble on deck for recovery. If lights are necessary, they are to be turned on at this time. The Deck leader also ensures that the recovery area is clear of all loose and extraneous items. The Deck Leader then prepares for the recovery by removing the safety net. All hands stand by to wait for clearance from the Bridge and from the Lab.

When the Winch Operator receives the all clear from the Lab and the Bridge, he then informs the Deck Leader that the recovery may begin.The Deck Leader verifies that the recovery crew is ready. When ready, the Deck Leader signals to the Winch Operator to begin the recovery. The Deck Leader directs the Winch Operator to hoist the rosette package out of the water until the end of the cable grip termination is about twelve inches from the cheeks of the sheave (marked with yellow tape).

The Winch Operator then retracts the boom and takes up on the winch to keep the package at the same elevation. This is the most difficult maneuver for the Winch Operator because he must keep the rosette package steadily positioned by the simultaneous operation of two controls. Therefore, once the rate of motion of the boom is fixed, the winch is adjusted for smooth continuous motion.

As the rosette package is brought close enough to the ship for the tag line personnel to attach their pole hooks, the Deck Leader will signal to the Winch Operator to STOP all motion of the boom and the winch. At which time, the pole hooks are attached to opposite fairleads on the base of the rosette frame. The poles are then set on deck (or secured in their holders) and a turn is taken around the respective inboard cleat and tensioned evenly. Once the tag line personnel are in position, the Deck Leader will signal to the Winch Operator to continue retracting the boom to complete the recovery process. The Tag Line Personnel must coordinate their tensioning together with the Winch Operator.

The Winch Operator will completely retract the boom and then set the rosette package on the deck while the Deck Leader is pulling the package slightly inboard to allow extra clearance for sampling.

Note: The rosette package shall be allowed to rest on deck in its natural orientation. Spinning or turning of the rosette package (e.g., for convenience of sampling) will cause undue stresses on the cable and termination due to the extremely short scope of the cable.

The Deck Leader will ensure that there is a slight amount of slack in the winch cable. The Winch Operator then secures the boom and winch hydraulic systems.

While the Tag Line Personnel are securing the rosette package to the deck, the Deck Leader is securing the safety net.

The WOCE person then flushes the CTD sensors with TRITON X solution and turns off the pinger if it was on. He or she should also inspect the CTD / rosette package for any signs of problems and record those in the science log.

The recovery operation is complete when the boat hook, pole hooks, and work vests are stowed, the rosette package is secured to the deck, and the tag lines are neatly flaked on deck in preparation for the next deployment.

In rough weather, the procedures will remain the same with the exception of a discretionary Third Tag Line Person who will assist the Aft Tag Line Person to hook onto the rosette. The Third Tag Line Person and the Aft Tag Line Person are to work as a team where one person mans the pole and hooks onto the rosette, then moves away (with the pole) from the recovery area, the other person mans the tag line, keeping tension as in a normal recovery.

  1. When the ship is underway, repeated 'dunkings' are done using a swinging forward and recovery motion.
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