Bridge Equipment, VTS, Damage Stability & Engineering Watch

In a mandatory VTS area, VTS instructions must be complied with — this is a condition of entry to the port. I acknowledge the instruction on the designated VTS working channel — name, call sign, and confirmation: "VTS [port name], this is [vessel name], MMSI [number], we confirm your instruction, understood and complying." I then implement the instruction — whether that is a speed reduction, a course alteration, a hold position, or a sequence change. I inform the Master of the VTS instruction and any change to the passage plan it requires. I log the time, content of the instruction, and our acknowledgement in the deck log. The VTS instruction does not override my obligations under the COLREGS — if compliance with the instruction would create a risk of collision with another vessel, I must take the safe action, immediately inform VTS of what I am doing and why, and rectify the conflict once it is safe to do so. VTS does not take command of the vessel — it coordinates traffic. Responsibility for safe navigation remains entirely with the Master and OOW.

Sound the general alarm and call the Master and all crew immediately. Assess the situation rapidly: determine which compartment is affected, estimate the rate of flooding, check the inclinometer for list and the bridge instruments for trim change. Activate all bilge pumps — the engineer must be told immediately to start emergency pumping and to identify the source of flooding. Close all watertight doors and watertight closures between the flooded compartment and the rest of the vessel. Transmit a Pan Pan on Ch 16 — give our position, that we are aground and taking on water, the number of persons on board, and our vessel's name. Contact MRCC and maintain communication. Check the damage stability booklet for the vessel's calculated residual stability in the event of flooding of this compartment — is the vessel expected to remain stable? Muster all persons at their emergency stations and prepare liferafts and LSA for rapid deployment if the situation deteriorates. Post a watch on the bilge level in the affected space and report changes to the Master every few minutes. Do not attempt to refloat the vessel until the flooding is assessed and controlled — attempting to free a grounded vessel that is flooding can make the situation significantly worse.

The echo sounder transmits an acoustic pulse from a transducer on the hull. The pulse travels to the seabed, reflects, and returns to the transducer. The time taken for the round trip, divided by two and multiplied by the speed of sound in water (approximately 1500 m/s), gives the depth. The depth displayed is typically depth below the transducer — not depth below the keel. I must know the distance from the keel to the transducer on our vessel and subtract this from the displayed depth to get true UKC. Limitations: the echo sounder looks straight down only — it gives no warning of a submerged wreck or a rock pinnacle ahead; it shows only once the vessel is over it. It can give a false bottom reading caused by a thermocline (a temperature layer with different acoustic properties) or a dense fish shoal. At high speed in a seaway, air bubbles entrapped under the hull can blank the transducer, giving no reading or erratic readings. The speed of sound in water varies with temperature, salinity and pressure — calibration is approximate. At depths over 200 metres the pulse repetition rate must be reduced to avoid the echo from one pulse overlapping with the transmission of the next.