The UK Marine Accident Investigation Branch (MAIB) has issued a safety bulletin (2/2011), according to Lloyd’s Register, following a recent failure of a wire rope attached to a Norsafe fast rescue boat, which resulted in the loss of life of a seafarer.
A possible contributing factor to the incident was the failure of the proximity/limit switch (Telemechanique XS7-C40FP260) fitted to the davit. This switch should have cut electrical power to the winch motor before the davit reached its stops, but failed to function. Hoisting was not stopped before the davit reached its stowed position, possibly resulting in an overload of the rescue boat falls.
This incident happened on the Schat-Harding SA 1.5 rescue boat davit system. It is also known that the same proximity/limit switches are fitted to Schat-Harding SA 1.75 davits.
The terminal within the proximity/limit switch was found to be corroded.
The bulletin is asking owners and managers of vessels equipped with lifeboat and/or rescue boat davits to follow and implement the manufacturer’s instructions in cases where Schat-Harding SA 1.5 or Schat-Harding SA 1.75 davits are fitted. They are also asked to ensure that all proximity/limit switches fitted to boat davit systems are tested on each occasion before a boat is hoisted and that such devices are not relied upon during operation; to follow manufacturers’ recommendations regarding the maintenance and periodic testing, examination and replacement of proximity/limit switches used on lifeboat and or rescue boat davit systems and seek clarification from manufacturers where ambiguity exists; and to verify the effectiveness of seals on electrical equipment fitted to boat davit systems on open decks.
Lloyd's Register also recommends owners and managers ensure that maintenance manuals include the necessary instructions, as required by SOLAS Regulation III/36.