Station Operations Troubleshooting

Shiptime is limited and expensive so keeping station operations, such as CTD-rosette deployment and recovery, running smoothly are critical to maintaining our station schedule. Station operations are organized for efficiency with stationary operations first (CTD, secchi, vertical net tows) then moving operations such as Manta & Bongo net tows. Although efficient use of shiptime is critical to finish all the scheduled stations & work. Safety is the top priority so protocols for prepping gear for station, deck ops, and 'over-the-side' operations change when the weather is rough. CTD-rosette prep, typically done 20mins before station arrival, may wait until station arrival to insure the safety of all participants & equipment. CTD-rosette descent speed may be reduced to 25-30m/min to minimize strain on the conductive wire.

This page outlines some strategies and general practices for maximizing ship/station time safely:

Primary strategy - redundancy: CalCOFI typically carries duplicate hardware for all mission-critical systems. We carry two complete CTD-rosette systems although only one is typically assembled. Most problems usually require the replacement of a defective or failing sensor, cable, or battery. Two complete sets of nets are onboard so unless the ship equipment fails (hydraulics, winches, for example), swapping out faulty gear should cause a minimal delay. At least two of everything: stopwatches, data acquisition workstations, sampling gear, analytical gear, etc will pay for themselves the first time they are needed.

Secondary strategy - continue station work if possible: while addressing a problem, continue with alternate station work. If CTD operations are not working, move on to other station work such as net tows. Net tows take about an hour, so this will allow troubleshooting problems with the CTD-rosette.

Troubleshooting

Bottle mistrips - rosette bottle(s) fail to close or close at the wrong depth: carousel mistrips are addressed in basically two ways: first mistrip, the trigger is cleaned with a Kimwipe or Q-tip of any debris or biological contaminate that may interfere with the trigger swing. If, after servicing, the same bottle mistrips again over the next few casts, the trigger is replaced. The carousel 'crown' is removed, disassembled and the trigger replaced. Having several spare triggers is highly recommended. Note: that bottle closure at the wrong depth may not be detected until nutrients or salts are run. Lanyard mis-rigging may also cause the bottle to mistrip.

CTD conductive wire problems:

• If the CTD wire becomes kinked or develop a mechanical weakness in the first several meters between the CTD & winch. It may be possible to continue to use the wire without re-terminating as long as signal continuity is intact. Move the wire grip (Chinese Fingers) above the problem area and loop the extra wire along the upper rosette ring. Secure the looped wire with strong cable ties. If signal continuity fails or is intermittent, reterminate above the problem spot.

• Loss of signal - isolate the individual wires and test continuity by attaching a 9-volt battery if a wire-tester is not onboard. Quick fix without reterminating when using the 4-pin pigtail: find a good single conductor, use that for signal; use the shield for ground; dummy unused connectors.

• Lack of bottle closure confirmation - this typically is a conductive wire issue, not software or deck unit. Approach this problem like a 'loss of signal' and rewire the signal & ground at the 4-pin termination & junction box. If the problem persists then look at the deck unit, CTD, and workstation for problems. Only make one change at a time when troubleshooting so you can track the solution.

• Conductive wire "jumps the shieve": on ships with side-by-side CTD & hydro winches, it may be possible to use the hydro winch to lift the CTD-rosette (or any tethered instrument) and reseat the wire.

  • If the CTD-rosette is suspended over the side, secure it to the cleats using the taglines to minimize the chances of losing the package if the wire parts.

  • Attach a wire grip (Chinese Fingers) to the CTD wire reversed, above the package, thimble up, ends down.

  • Switch the hydraulics to the hydro winch.

  • Attach the hydro wire shackle to the wire grip thimble and use the hydro winch to lift the CTD-rosette until there is enough slack to slip the wire back into the shieve.

  • Keep the CTD wire under tension so it stays in place as you carefully pay out wire on the hydro winch.

  • Once the CTD wire is supporting the weight of the CTD-rosette, unshackle the hydro wire and remove the wire grip.

  • Return the CTD-rosette to deck and assess any damage to the conductive wire. If the CTD wire is damaged, refer to the CTD wire section above.

• Slip-rings problems: the CTD winch conductive wire interfaces with the junction box via the slip rings. Most ships have maintenance-free slip rings but they still require soldering the slip-rings connectors to the wire conductors. These connections move when the winch rotates so if any of the soldered connections get wet or break, it will interrupt the signal to the CTD.

Rough Weather Protocols

• Net tows may be cancelled if a persistent true wind speed is above ~25-30kts; secondary criteria is sea state.
• If weather decks are secured, CTD-rosette bottle rigging may wait until station arrival; secondary criteria is if the CTD quarterdeck is in the lee of the wind. If protected, bottle-rigging may be performed with permission from the bridge & watchleader.
• If the sea state allows the careful deployment of the CTD-rosette then the descent speed may stay between 25-30m/min.
• The sea state can worsen over the CTD cast duration so decide wisely to deploy under marginal conditions.