Sad to read recent reports about Cyclone Gabrielle causing damage and loss of life in New Zealand.
A question for our ship's crew and those with knowledge of navigating - what evasive action can a ship's captain or navigator take to avoid a Cyclone? Is it just as easy as navigating a new route or are ships required to keep with a predetermined route? Increasing speed to get out of the area seems like a good option, but is it as easy as just saying "full speed ahead"? The Chief Engineer would need to be involved in the decision, especially if the decision would use more fuel.
We try to avoid heading into or being anywhere near a Tropical Revolving Storm (a TRS - the type of storm that Hurricanes, Typhoons, and Cyclones are) in the first place (prevention being the best cure so to speak) but if we are caught up right in the middle or just in front of one, the bridge team will try to place and keep the ship in the navigable semicircle of the TRS and definitely out of the dangerous quadrant - to do with the increased severity of the wind and swells in that dangerous quadrant as well as the typical path of a TRS which changes depending on whether you're in the Northern or Southern hemisphere.
The goal is to stay hove to but with steerage to keep the wind in the right place on the ship's bow in the TRS's rear area (behind the dangerous quadrant) for any ship (even QE2) to allow the TRS to move ahead and track away.
The other goal if previously in the path of the TRS or otherwise being caught in it in the dangerous quadrant without being able to overtake it such as on a slow oil tanker is to get into the navigable semicircle of the TRS if possible as the winds will drive the ship out of the path of the TRS in the navigable semicircle as opposed to into the path of the TRS in the dangerous quadrant.
I suspect QE2 was in Hurricane Luis's rear area when she was hit by the 90+ foot waves in September 1995 given she was hove to according to accounts but still making way enough for steerage into the prevailing conditions with the wind on her starboard bow otherwise even she could've been in trouble given the severe conditions.
Overtaking the storm from within, if that's even possible given the severe conditions is definitely not what to do as far as we've been taught. One also has to keep an eye on whether the wind is backing or veering as the ship's bow has to be placed according to either regardless of location in the TRS and dependent on whether it's a Northern or Southern hemisphere TRS.
If caught in a TRS we'd be on hand steering with the ABs taking turns on the helm matching with the OoWs navigational watchkeeping schedule and we wouldn't be using the autopilot given it could be overwhelmed by the particularly severe conditions depending on it's settings and operating parameters/limits and could lose control of the ship's steerage with other consequences when it then attempts to get the ship back on course with a series of major helm inputs, such as stalling the main engine on an oil tanker or ripping the rudder off it's stock given the forces involved on a fully deflected rudder given maximum practicable speed is required within the different quadrants and semicircles of the TRS apart from being hove to in the rear quadrant area of the TRS. The human touch, feel for the ship, and experience being better and safer in this situation.
Maximum practicable speed being influenced by the severe conditions (the TRS will be working against the ship a lot), main engine operating parameters (avoiding overheating and overspeed etc), and whether the ship's bow is up to the amount of pounding (slamming) at a given speed in the severe conditions given it's the end of the ship that'll be taking the brunt of the TRS.
Increasing speed to overtake a TRS bearing down on your position would've likely been possible on a ship as fast as QE2 given the TRS's ground track speed isn't usually that fast, and the metrological signs of an approaching TRS are quite identifiable, quite apart from the detailed weather forecasting that is available as long as it's up-to-date to avoid the case of SS El Faro.
Alternative routes to avoid the TRS will be suggested within the bridge team and taken if necessary. The passage plan will be altered and the monitored route (the path the ship is navigated along) will then be updated on the ECDIS (Electronic Chart Display Information System) these days. Commercial pressures take a back seat to TRSs as ships are lost otherwise along with their whole crews as successfully abandoning ship and surviving the elements doesn't usually pan out very well in a TRS.
In normal circumstances the monitored route on an ECDIS can be tweaked quite often for many reasons such as a bunkering port not being confirmed out of several options until a couple of days before the end of crossing an ocean.
We wouldn't make port in any area likely to be affected significantly by the TRS, but we would seek the shelter islands can offer while hove to if reachable and appropriate.
If we encounter or suspect a TRS (or any storm above Beaufort Force 10 - including low pressures) that doesn't already have warnings out for it from other ships in the vicinity or from the likes of NOAA or the Met Office we are required by SOLAS to report it in detail, also being required to keep giving updates on it while remaining in it's vicinity.
Topic: Ships in stormy seas (Read 18671 times)
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Aug 07, 2020, 10:42 PM