Web Content Display Web Content Display

Crew Endurance in Depth

Sleep and circadian-based watch schedules are an integral part of fleet readiness and operational performance.

In this section, we'll take an in-depth view of Crew Endurance.

Web Content Display Web Content Display

 

The Problem: Fatigue caused by inadequate sleep

Venn diagram: Stress, Suicide, Fatigue, MishapsFatigue has been shown to have repeatable, tangible and measurable negative effects on readiness, effectiveness, and safety. It results in poor crew endurance -- limiting a crew's spare capacity. When faced with an unexpected emergency, the crew may be unable to meet the mission requirements.

Crew endurance is affected by multiple factors:

  • Too little sleep
  • Long work days with little time for recovery
  • Psychological stress
  • Physical fitness
  • Fatigue has been shown to be related to:
    • Stress
    • Suicide
    • Mishaps

Solution: A Circadian-based Watch Schedule

Several alternative schedules exist to ensure that crew and staff are well rested and better prepared to perform their duties. Numerous shipboard studies have shown the value of a circadian watchbill and schedule.

No one size fits all!

There are several common variations of watch schedules, each with its own merits and tradeoffs. Become familiar with some of the considerations below before choosing a schedule for your crew. The NPS Crew Endurance Team is also available for further consultation. 

Back to Top

 

How to Increase Sailors' Endurance

  • Focus on alert and engaged watchstanders.
  • Learn and understand the effects of good sleep practices.
  • Use the 24-hour circadian rhythm to set the foundation.
  • Build a stable daily work schedule including the watch bill

      that maximizes rest opportunities at the same time each day (fixed schedule).

  • One size does not fill all—consider tradeoffs.
  • Get supporting analysis on your schedule before you make a final decision.

 

Sleep is a weapon. A clear mind is a combat edge.

 

See also, these relevant links: Choosing the Right Rotation, and Planning and Implementation for more details.

 

Back to Top

Web Content Display Web Content Display

Types of Rotations

No one size fits all!

There are several common variations of circadian-based watch schedules, each with its own merits and tradeoffs. 

Common/Popular Circadian Schedules include:

Characteristics

  • Requires 4 watches. If the entire ship cannot support 4 sections, focus on control stations—OOD, EOOW, TAO to ensure there are well-rested decision makers.
  • Teams stand same 2 watches each day (for example,12-03 and 00-03).
  • When rotating to a new shift, each shift rotates forward one watch by extending watches by 1 hour on rotation days. Limit the “spin” of the rotations or align with port visits so that everyone gets into the routine. Three weeks or more is better.
  • Protect the sleep periods of day sleepers and encourage crew to sleep at least 7 hours each day.
  • Meal hours may need to be adjusted to support hot meals for all rotations. Consider a late night hot meal too.

Pros

  • Meals every 6 hours
  • Shorter watches so watch standers are more alert
  • Sailors in 3 of the 4 Watch Sections have the opportunity for a single sleep period of 7 hours or more.

Cons

  • More frequent watch turnover
  • Split sleep periods are required for Watch Section 1.

Characteristics

  • Requires 4 watches.
  • Teams stand same watch each day (for example, 01-07).
  • When rotating to a new shift, each shift rotates forward.
  • Limit the “spin” of the rotations or consider aligning rotation with port visits so that everyone gets into the routine. Three weeks or more is better.
  • Protect the sleep periods of day sleepers and encourage crew to sleep at least 7 hours each day.
  •  Meal hours may need to be adjusted to support hot meals for all rotations. Consider a late night hot meal too.

Pros

  • Sailors in Section 1 are allowed to get 2 extra hours of sleep to compensate for sleep loss due to night shiftwork.
  • Sailors in all sections sleep in one contiguous period.
  • Meals every 6 hours.

Cons

  • Long duration watches.

       Watches are 6 hours long, which may be too long for some watches.

Characteristics

  • Requires 3 watches.
  • Teams stand same 2 watches each day (for example, 00-04 and 12-04).
  • When rotating to a new shift, each shift rotates forward by one watch every 3+ weeks or consider aligning rotation with port visits.
  • Limit the “spin” of the rotations so that everyone gets into the routine.
  • Protect the sleep periods of day sleepers and encourage crew to sleep at least 7 hours each day.
  • Meal hours may need to be adjusted to support hot meals for all rotations. Consider a late night hot meal.

Pros

  • Sailors in Watch Section 1 are allowed to get 2 extra hours of sleep to compensate for sleep loss due to night shiftwork.

Cons

  • Sailors in Watch Section 1 have to split their sleep into 2 periods.
  • Meals (breakfast, lunch, dinner) are served every 4 hours rather than the more conventional 6 hour delay between lunch and dinner.
  • Early dinner.
  • Requirement for mid-rats for Sailors who are sleeping during dinner hours.
  • Ops brief after the early dinner.

 

All circadian-based  rotations are based around a 24-hr day with stable sleep periods and are generally preferable to rotating watches. If there are enough trained watchstanders to support a 4-section watchbill, the 3/9 and 6/18 schedules are good options. The 8/16 and 4/8 are 3-section options that have been used with some success. If a 2-section watchbill (6/6, 7/5, or 12/12) are required, care should be taken to ensure that all watchstanders have protected sleep periods during their time off watch. In addition, shift rotation becomes more critical when implementing a 2-section watchbill. See also, Choosing the Right Rotation for more help in making scheduling decisions.   

Common Non-Circadian Schedules (to be avoided if at all possible!)

  • 5/10, 6/12, & 5/15

Schedules that result in shorter than a 24-hour day impose a type of jetlag that will quickly result in an unnecessarily and extremely fatigued crew.

Back to Top

Web Content Display Web Content Display

 

Best Practices:

(Based on actual success stories from ships implementing circadian watch rotations.)

  • Eliminate reveille call to allow early morning watch standers to sleep in.
  • Eliminate taps, allowing watchstanders who are sleeping to remain asleep.
  • Move evening prayer to lunchtime.
  • Hold quarters later in the day--before lunch. Or do not require quarters in the morning for all hands. Consider midday quarters/Officers-call.
  • Establish mandatory "protected sleep" periods for each watch rotation, i.e., "protected" from scheduled meetings, training , drills, etc.
  • Maximize protected sleep periods prior to night watches.
  • Modify meal hours to accommodate watchstanders - expand breakfast hours (and other meals as required) to cover turnover times.
  • Schedule routine meetings after 0900 and before 1600.
  • Schedule daily Ops briefs during the afternoon.
  • Move Divisional Quarters to late morning or after lunch.

Worst Practices

(Based on actual stories and feedback from the fleet)

Had bad experiences on "my ship" because I/we:

  • Didn't adjust the daily routine to accommodate night watchstanders.
  • Required night watch teams to attend morning quarters.
  • Held meetings right after breakfast or after dinner that required attendance by watchstanders who are scheduled to be asleep.
  • “We required everyone to attend quarters in the morning, regardless of what watch they had, so the 2 weeks on 00-03 was always hell.”
  • “We did messing and berthing at 0800.”
  • “We enforced an “all hands awake” period from 0900 to 1500 each day.”
  • “We never changed meal hours so the night watches missed either dinner or breakfast.”
  • “Leadership did not respect sleep periods – they would call you any time with routine questions.”
  • “I was never allowed to delegate meetings or briefs, so I was not able to catch up on sleep.”
  • Tried to apply the same watch template to all situations.
  • Didn't seek frequent feedback from watchstanders and other crew.

Back to Top

Web Content Display Web Content Display

Web Content Display Web Content Display

Planning Factors

  • Type of rotation: Circadian is better
  • Length of watches: Shorter is usually better
  • # of sections: More is usually better
  • Rotation times: Cardinal points (3,6,9,12) are simpler
  • Direction of rotation: Forward is usually better
  • Designated sleep times: Sleep at same time each day
  • # Days in each rotation: Three weeks or more is better
  • Day of turnover: Weekends allow flexibility
  • Turnover: Add hours vice making drastic change

Constraints to consider

  • Heat stress limitations (PHEL curves)
  • Drills, briefs and debriefs
  • Watch turnover SOP
  • Pre-watch plant tours
  • Watch team cohesion
  • Meal hours
  • Daily routine
  • Berthing arrangements
  • Special Evolutions
  • UNREP
  • Flight Quarters
  • Well deck ops

Web Content Display Web Content Display

Contact

Crew Endurance Team
Naval Postgraduate School

CrewEndurance@nps.edu

See also About Us for a complete list of contacts.