Hurricane Irma has sent shipping into disarray, particularly for cruise passengers. Around 40,000 holidaymakers are estimated to have been affected by disruption to scheduled cruises this week and this figure could rise further as Irma speeds through the Caribbean towards southern Florida.
The hurricane has already devastated areas of the British Virgin Islands, St Martin, Barbuda, St Barthelemy and Anguilla and AIS data shows 12 cruise ships are currently still in Irma’s path, but there is no cause of concern thanks to weather routing guidance, according to Tom Strang, senior vice-president, maritime affairs at Carnival Corporation & plc.
“Modern cruise vessels are designed to be able to cope with such extreme weather,” he explains. “We have contracted-in weather service providers, who have sophisticated weather prediction software and models that allow us to suggest best options to avoid the worst weather to our vessels’ masters.”
As explained by UK Chamber of Shipping, operators that are able to re-route vessels out of a storm’s path will do so, but this can have massive cost implications, as an average day’s sailing costs around $80,000 at today’s prices.
However, a sophisticated system monitoring weather systems, as used by Shell, allows shore-based staff to advise a ship’s master to reroute a vessel before it reaches the affected area. Not only does this decrease risk to the ship and its crew, it can also help reduce fuel consumption.
In addition, the know-how of experienced mariners is indispensable, the Chamber notes.
“A canny captain will navigate his vessel to the “low side” of the storm, usually the side anti-clockwise from its leading edge, where wind speeds will be lower and waves will be shallower.”
The master also needs to give the vessel “steering-way” – that is, the vessel must keep moving forward with enough power to steer, which overrides the forces that wind and waves have upon the vessel. The ship’s bow must be kept pointing into the waves so that the vessel can plough through them safely, which helps prevent waves from striking the ship on its sides.
What is more, being at sea can be a safer option for vessels caught in extreme weather, as it eliminates the risk of vessels being pushed up against the quay. The US Coast Guard has advised all ocean-going commercial vessels to make plans to leave ports in south Florida at least 24 hours before the onset of gale-force winds from Irma.
Further, the heavier the vessel the better during a hurricane – the most dangerous ship is an empty one. The weight of cargo helps stabilise the ship against the waves. Ballast water alone is not always enough to counteract the ocean’s force upon the ship.
Nevertheless, ships will roll (tilt from side to side) even when laden, which can be hard on the crew. Many large vessels are, however, equipped with anti-heeling systems or stabilisers, which compensate for the tilting angle of the ship and help right it.
Stabilisers, however, cannot do anything to prevent the vessel from pitching (rocking forwards and backwards). The structure of the hull can be compromised if the ship repeatedly slams during troughs between waves – even though hulls today are made of thick steel. That’s why being able to avoid extreme weather at the earliest opportunity and navigating to calmer waters is critical for ships and their crew.