The Ambiguous Mooring Order
At 1730 you are the petty officer in charge of a line-handling party on a pier in Manila Bay. The ship must shift 40 meters astern. The duty officer's radio order is: “Take a turn on the after spring and hold her, then slack the headline when the tug takes the strain-but don't let the bow come off the pier.” You have four line handlers: one on the headline, one on the after spring, and a tug made fast forward. The tide is flooding at 1.5 knots, and the wind is from the southwest at 12 knots. A junior line handler has already taken two turns on the after spring and made it fast. The headline is still bar-taut. The tug has not yet taken strain. The duty officer repeats, “Slack the headline now.” You must decide whether to comply immediately, send a clear read-back, and later write a concise radio-log entry. A wrong move could part a line or swing the bow into the pier.
1. Identify two ambiguous elements in the duty officer's order and explain how a line handler could reasonably misread each one.
Read the worked answer
Ambiguity 1: “Take a turn … and hold her.” In line handling, “take a turn” can mean one wrap around a bitt while the line is still controlled by hand, or it can mean “make fast.” The junior handler took two turns and made fast, which is not the same as holding by hand. If the order meant “control, do not make fast,” the line is now over-secured and cannot be eased quickly.
Ambiguity 2: “Slack the headline when the tug takes the strain” versus “Slack the headline now.” The first clause sets a condition: the tug must first take strain. The second clause removes that condition without saying so. A handler could hear “now” as overriding the condition, or could hear the conditional clause as still controlling. The conflict matters because the headline is the only line presently restraining the bow.
A third weakness is “don't let the bow come off the pier,” which gives no measurable limit-distance, angle, or line tension. The operationally critical ambiguity is the timing of the headline, because slacking it before the tug holds the bow could let the flooding tide and southwest wind push the bow off the pier.
2. Write the radio read-back you would send, in 35 words or fewer. It must confirm line status, flag the unresolved condition, and request confirmation.
Read the worked answer
Read-back (29 words): “Duty Officer, line party: after spring is made fast. Headline still bar-taut. Tug has not taken strain. I will hold headline until tug strains, then slack easy. Confirm-over.”
Why this works: It does not simply say “Roger.” It states the actual condition of both lines, identifies the unmet condition in the order, states the intended action, and asks for confirmation. That gives the duty officer a chance to correct the interpretation before a line is eased. The read-back also creates a clear radio-log record of what was understood at 1730.
3. Explain why obeying “Slack the headline now” immediately could be unsafe, and state the condition you would insist on before slacking.
Read the worked answer
The headline is holding the bow against the pier while the after spring is made fast. If the headline is slacked before the tug has strain, the bow has no forward restraint at the moment the flooding tide and southwest wind are pushing it off. The after spring may limit fore-and-aft movement, but it does not necessarily keep the bow from paying off. A parted or surging line can also injure the line handlers.
I would insist on two conditions: the tug must have visible strain and be holding the bow, and the duty officer must confirm that the after spring is holding as intended. Then I would slack the headline in controlled increments-one turn at a time, keeping tension-while watching the bow and the line, rather than letting it run. If the tug does not take strain, I would keep the headline fast and report that the condition for slacking has not been met.