202520 Rerouting risks - severe weather
As edited from Gard here
In recent months, many vessels have rerouted around South Africa to avoid threats to shipping from Houthi attacks in the Red Sea. However, this comes with its own set of risks. Vessels spend more time at sea with more exposure to difficult weather and the attendant consequences.
The southern hemisphere winter of 2024 saw some severe weather conditions off the Cape of Good Hope with several incidents occurring. The area has a reputation for stormy confused seas, large swells and rogue waves, which pose extra risks for ships and their crews. Sadly, there have been fatalities among crew working on deck and who have been struck by waves in heavy weather off the Cape.
Cargo stows on container, bulk, vehicle and general cargo vessels are particularly vulnerable to more extreme rolling and pitching. Stowage failures can lead to more than cargo damage. They can result in structural damage, fires and may also cause the ship to list, compromising stability and potentially disabling the ship.
Cargo that falls overboard can also endanger other vessels at sea. There is inevitably an environmental impact from cargo that sinks or ends up washing ashore as debris. Gard has seen clean-up costs in several cases running into many millions of dollars, particularly if plastic nurdles (below, left) are involved.
Lessons learned
- It is a good investment to refresh and update the skills of navigators in storm avoidance, weather analysis, and routing strategies.
- Lashings may need checking as they may have slackened during the voyage. However, it is important that such checks are done in good time and safe conditions. If a stow failure does occur it may also be unsafe to send the crew into cargo areas to try and re-secure it until better conditions permit.
- Heavy seas can cause large movements in the lubrication oil tanks, such that the supply to the lubricating oil pumps stops. This can trigger a lubricating oil low level alarm, which in turn can cause an automatic shutdown of the engines.
- In case of a major casualty off South Africa, there are few ports in the area that have the necessary scale and infrastructure to accommodate the largest container ships. If something goes wrong, a large ship in distress will have few alternatives if a port of refuge is needed.