Scheduling of Days on Station
When a cruise plan has been worked out, the WHOI Marine Operations Coordinator will draw up a schedule for the cruise, showing transit time, days on station, and port calls.
Generally, a cruise is scheduled to provide two days in port prior to sailing for the loading of scientific equipment and supplies. Scientists may join the ship the evening before departure (moving aboard earlier requires special arrangements with WHOI Port Office personnel). Port departure time is not advertized but was considered when determining the scheduled number of days in port; the possibility of a late departure time effectively adds flexibility to the port time available to complete cruise preparations. The figure given for transit time is purposely conservative, allowing for the safe and reasonable operation of Atlantis and for any unforeseen contingencies which could delay the ship’s arrival on station. Some research party leaders, however, assuming an early departure time and noting the maximum speed of which Atlantis is capable, optimistically schedule extra scientific work for some of the designated transit days. After joining the ship, they attempt to persuade the crew to alter the original schedule to accommodate these new plans, placing the crew in a difficult position. Therefore, prospective science party members are warned not to tamper with the departure time and transit day safety margin provided. The Marine Operations Coordinator reserves the right to determine cruise scheduling as he deems necessary, and changes in the science program should be discussed with him even if the published schedule appears to provide adequate time. Generally, the Master determines the port departure time based upon completion of ship preparations and timely arrival at the first work station listed in the cruise plan. The Chief Scientist determines the site departure time based upon research needs and arrival in port at a time affording a full work day ashore on the first scheduled port day.
A day on station (DOS) is normally a dive day consisting of a 24-hour period (midnight to midnight). However, scheduling considerations may require that the support ship arrive on station for the first dive in the early morning rather than at midnight. Additionally, there may be a requirement for departure from the dive site soon after the submersible is recovered rather than after the full 24 hours have elapsed. If the science program requires that these time periods be available on station, the Alvin Group must be informed well in advance in case schedule changes are required.
The DOS is divided into three parts: predive preparation, diving, and postdive replenishment. After a dive, battery recharging takes 8-12 hours. Part of this time may be simultaneously spent in conducting post-dive servicing and pre-dive checks as well. Post-dive servicing normally takes about an hour and pre-dive checks normally take about two hours.
Following a dive series, the support ship transits to port where a minimum of one day after the arrival day is scheduled for science party disembarkation. During this time the science party may live aboard ship. (At some port stops, however, the galley may be closed, obligating scientists and crew to eat ashore.) Generally, those in charge of scheduling allow considerable latitude in determining the dive site departure time, in the belief that the flexibility of a few extra hours at the end of a cruise may have significant impact on the science program’s success.