The Overloaded Watch Rota
You are the senior cadet on a four-person duty watch aboard a training vessel alongside harbour. The watch must maintain a continuous two-person presence on the upper deck from 18:00 to 06:00 (twelve hours). Each person can stand at most four hours on deck in total, and no one may stand more than two consecutive hours without a break of at least one hour. Cadet B reports a persistent headache and blurred vision after four hours of a previous task and says she feels able to continue. Cadet C is fully fit but has an examination at 08:00 and asks to be excused the 02:00 to 06:00 period. Cadet D is willing but has only completed half of the mandatory fire-round training and cannot be left unsupervised. You are expected to present a written plan to the duty officer in twenty minutes.
1. Construct a rota that satisfies every stated constraint, or demonstrate that none exists. Show your reasoning.
Read the worked answer
Total deck-hours required: 2 people x 12 hours = 24 person-hours. Maximum available from four people at four hours each = 16 person-hours. The requirement therefore cannot be met: 24 > 16. This is a hard infeasibility, independent of preferences. The correct answer is to state that no compliant rota exists and to escalate for one of: relaxation of the two-person rule, authorisation of overtime beyond four hours, or additional personnel. Attempting to hide the shortfall by rostering someone for six hours is a serious error, not a solution.
2. Separately from the maths, what should you do about Cadet B, and why does her willingness not settle the matter?
Read the worked answer
Headache with blurred vision is a possible red-flag symptom and is not a matter for the cadet's own judgement alone. Willingness is not the same as fitness; a cadet may under-report to avoid appearing weak. The correct action is to refer her to the duty medical officer or responsible adult before any further deck duty, record the report and the referral, and not roster her until cleared. If no medical cover is available, treat her as unfit and find another solution. The principle is that safety decisions rest with the person accountable, informed by competent advice, not with the person who most wants to continue.
3. Cadet C's request and Cadet D's incomplete training each constrain the plan. How do you weigh them against each other and against the two-person rule?
Read the worked answer
Rank by consequence, not by who asked most persuasively. The two-person rule and supervision of an untrained cadet are safety-critical: breaching them risks injury or an unsupervised emergency. C's examination is important but is a personal-welfare matter that can be mitigated (earlier sleep, swap, short notice to the examining staff). D cannot be rostered unsupervised, so D counts only alongside a qualified person. A defensible answer acknowledges the conflict, protects the safety constraints first, seeks a supervised pairing for D if numbers allow, and escalates C's request rather than silently granting or refusing it. It also notes that, given the shortfall, the whole rota must go to the duty officer as a problem, not as a finished product.