Gale, Gale, Storm: Playing Duck, Duck, Goose in the Southern Ocean

On March 31, 2018 the Sailing School Vessel Robert C. Seamans departed Lyttleton, New Zealand, bound for Pape’ete, Tahiti. During its voyage, carrying 21 students and 13 crewmembers, the 134’ ship experienced multiple consecutive days of gale-strength and stronger weather while executing an avoidance of Tropical Cyclone Keni. Despite the variety of forecast products available in the days leading up to and during these gale events, the ship was caught in a rapidly intensifying low, ultimately facing more than 12 hours of storm-force winds.

Voyage planning is a complex process, and modern mariners rely on a variety of weather products when assembling and executing a voyage plan. Heavy weather avoidance is a crucial component of voyage planning, especially for a sailing ship with an average travelling speed of 5-7kts. On an ocean passage, it is not uncommon to be far enough offshore to be out of range of ports of refuge. With limited ability to outrun a big weather system, sometimes the only option available is to heave-to and ‘ride it out.’

In early April, 2018, as the Robert C. Seamans travelled toward the Chatham Islands, located 450 nautical miles east of Lyttelton, Tropical Cyclone Keni formed in the tropics close to Fiji. The Chatham Islands are too small to offer safe harbor for a ship as big as Seamans in any kind of heavy weather, and certainly not in a tropical cyclone. As the ship prepared to depart the Chathams, forecast models showed that Keni would likely travel southeast, gaining speed as it moved into higher latitudes. Rather than attempt to get east of the cyclone, the decision was made to head north-northwest, allowing Keni to pass well to our east.

At this point, the available forecast models agreed on TC Keni’s track. Allowing TC Keni to pass east of us appeared to be a prudent move. There was a cost to this prudence; other large weather systems forming in the region resulted in multiple gales directly impacting us as we waited, hove-to, for Keni to pass. Preparations were made in every part of the ship for heavy weather, and ultimately it was these preparations that allowed us to ‘weather’ the storm that formed as the last of 3 consecutive gales blew through. The rapidity with which the wind increased from gale to storm-force could have been disastrous had we not been in a heavy weather posture as it developed.

This talk will describe the decision processes aboard the Robert C. Seamans, weather information used, preparations of the vessel, and lessons learned.