A Deepening Low on the Westbound Route
M/V Barents Star, an 18,000 dwt chemical tanker in ballast (draft 5.6 m fwd, 6.2 m aft), is westbound at 66°20′N 004°00′E on 14 November, steering 250° at 12 kt. The 0600 synoptic chart shows a low of 975 hPa at 68°00′N 000°00′E, forecast to deepen to 960 hPa and move to 67°00′N 005°00′E by 1800, with a trough line ahead of it. The ship's barograph has fallen 3.4 hPa in the last 3 hours, and the wind has veered from SSW 25 kt to SW 35 kt in the past hour. The forecast is SW gale 8, veering W storm 10, sea 7–8 m, with a moderate risk of icing in showers. The nearest coast is 90 NM to the east, there is a 1.5 kt north-east-going current, and the schedule requires arrival at a fjord terminal in 36 hours. The vessel has a stiff GM in ballast and has begun to pound in head seas.
1. Interpret the barograph and wind observations: where is the low relative to the ship, and in which semicircle is she? What will the wind and pressure do next?
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Reading the observations. The barometer has fallen 3.4 hPa in 3 h - about 1.1 hPa/h, rapid deepening consistent with the forecast 975 → 960 hPa. The wind has veered from SSW 25 kt to SW 35 kt. Around a Northern Hemisphere low the wind circulates anticlockwise, so a SW wind places the ship to the south-east of the centre: the low is to the north-west of the ship.
Which semicircle? The forecast track from 68°N 000°E to 67°N 005°E runs roughly ESE (about 120°). The ship lies south of that track - on the right-hand side looking along the direction of motion - the dangerous semicircle, where the storm's translation adds to the wind and the seas are highest and most confused. The track would also pass only about 40 NM north of the ship, far too close.
What happens next. As the centre passes to the north, the wind will veer further, SW → W → NW, and the pressure will keep falling until the centre is abeam, then rise. The observed veering is itself confirmation that the centre will pass north of the ship and that the worst is still ahead, not behind.
2. Recommend a course and speed plan for the next 12 hours and justify it.
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Plan: put the wind on the starboard bow and make southing, away from the track and away from the coast.
- Alter from 250° to about 200–210°. With the wind at SW (225°) that puts it roughly 20–25° on the starboard bow and increases distance from the forecast track instead of converging with it.
- Reduce speed to 6–8 kt. The ship is in ballast, stiff, and already pounding; 12 kt into a 7–8 m sea risks slamming, propeller racing and structural damage, and slower speed reduces the apparent wind and the spray.
- Do not turn east toward the coast: 90 NM to lee with a W storm 10 and a north-east-going current is a lee shore, and it also takes the ship toward the low's track.
- Keep the sea fine on the bow rather than on the beam. If the ship cannot hold 200–210°, heave to with the wind on the starboard bow rather than run before it.
- Watch barometer and wind: falling pressure with veering wind means the centre is still approaching; backing wind with rising pressure would show she is in the other semicircle.
Inform the master and the engine room: this is now a heavy-weather passage, not a schedule passage.
3. What would you record and report, and how do you handle the commercial pressure from the 36-hour schedule?
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Recording and reporting.
- Log the three-hourly pressure readings and tendency, wind direction and force, sea and swell, and every course and speed change with the time and the reason. The log is the evidence that the deviation was deliberate and weather-driven.
- Report to the company with a brief situation report: position, weather, action taken, expected delay and next report time. The 36-hour schedule is a commercial matter; the master's overriding authority for the safety of ship and crew comes first, and the company's SMS should support that.
- Advise charterers and agents of the ETA change so the terminal and pilot can replan.
- Check cargo and deck securing, watertight closures, the crew's heavy-weather routine (no work on deck), watchkeeping arrangements, and refresh the forecast via NAVTEX/GRIB every six hours.
- If the weather is worse than forecast, heave to and wait rather than press on. A day lost is recoverable; a damaged ship or an injured crew is not.