The standing rigging of a 60-foot inspected passenger-carrying sailing catamaran failed recently in the Florida Keys, causing its rotating wing spar mast to collapse, according to a Coast Guard-issued safety alert.
Evidence suggests that the port shroud parted where it exits a swageless mechanical end fitting on the upper mast at a common shrouds/stay connection.
Although there were a number of passengers on board at the time there were no injuries reported.
A six-year review of Coast Guard casualty data shows 28 similar casualties involving inspected sailing vessels. Of those 28, nine involved the failure of mast, spars and rigging components leading to dismastings; six of those involved sailing catamarans. Two separate catamaran dismastings resulted in two fatalities.
Common among the dismasting casualties was the failure of the mast's standing rigging. While this investigation is ongoing, initial forensic metallurgical analysis of the failed cable strands showed visual corrosion and evidence of fatigue failure. The shroud cable and swageless end fitting had been installed seven years earlier.
Manufacturer published guidelines on mast and rigging system maintenance can be found in "Rigging Service Guidelines" published by Navtec Rigging Solutions. Practical standing rigging inspection information from a marine surveyor's perspective is available by clicking here.