Improving safety standards for workboat launch and recovery
DNV GL is reviewing a new voluntary certification standard covering the davits used to launch and recover workboats and tenders writes Dag Pike.
The new standard includes some of the design features that davit manufacturer Vestdavit has long advocated for safer and more efficient boat handling.
According to Vestdavit, the need for these standards has been brought into focus by the development of smarter, more complex davit designs, where lack of clarity on documentation can lead to incorrect use, and potentially to accidents. DNV GL's proposed standard observes that existing certification approaches for non-lifesaving launching appliances are based around lifeboats’ davit standards rather than being specific to many workboat systems. This is an approach that it does not believe meets market or customer requirements, according to the class society.
To address this problem, the new standard for non-LSA davits emphasises solutions that are more forgiving of system and human failures. The standard calls for more redundancy in critical components, control and monitoring systems, painter arrangements, launching cradles and radio remote control systems. It also includes criteria on where to position the davit on a mother-ship, and for winches themselves and release mechanisms. In addition, the standards move with the times by opening the way for fibre rope use for the davit falls instead of insisting on wire ropes.
The new standards also recommend inclusion of an efficient shock absorber to dampen forces on boat launch and recovery, to limit the dynamic effect caused by the interaction with the waves.
The standards also accept the direct connection between equipment performance and different sea states; today, IMO SOLAS requirements offer only minimum handling speeds for davit lifting and lowering operations regardless of sea conditions. In higher sea states, boats need to be hoisted clear of the water quickly enough to avoid being lifted by the next wave. When that wave subsides, the rope is slack, and the boat and its occupants can drop dangerously. A Vestdavit spokesperson commented, “We have consistently argued that basing operations on the sea state in which the vessel is operating is not only favourable, but essential for safe boat handling.” Vestdavit has supplied over 1700 specialised davit systems that incorporate a variety of safety features.
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