It’s fair to conclude that every fishing vessel greater than 35’ in length is fitted with some type of lifting appliance. The term lifting appliance is commonly used by Transport Canada to describe any kind of item onboard a fishing vessel that is used to lift gear, fish and fishing equipment. These items are typically a mast and boom arrangement such as an offloading boom and a boom for handling dragging or seining gear. This equipment is typically attached to the deckhouse top and comprises a single or A-Frame type mast on a foundation and connected to the house top with pipe and cable stays. The boom(s) is supported to the mast by cables.
Mast and boom arrangements are typically arranged and constructed based on experience and relies heavily on what has worked in the past on similar boats for similar operations. The array of fixed pipe stays and cables creates a system where the applied loads on the lifting appliance are spread out over many contact points on the vessel’s deck and house structure and are often carried down into the hull sides and stem head. Vessel owners are well aware of the limits of these lifting appliances and this setup has proven to be very effective.
Becoming more common these days is the installation of a crane. The crane is often located on the upper deck or house top, away from the busy main deck area and is attached to a foundation that is bolted to the deck or house top.
In the aquaculture industry, the crane(s) is most likely attached to the main deck of a workboat and is often larger in capacity when compared to fishing vessels. A crane has specific load capacities and this should be strictly adhered to when operating the crane.
Although a mast and boom arrangement is typically accepted as installed, it is recommended that all lifting appliances be analyzed and tested for a certain safe working load. A crane is installed on a foundation which is connected to the house or deck over a relatively small area of contact. The crane foundation and the underlying structure to which it is attached should be fully analyzed and engineered for the crane design limits to ensure the attachment will not fail under design loads. From this analysis, including finite element analysis (FEA), the vessel owner and installer can be properly advised on the installation details. This would typically be reinforced house or deck structure, including additional frames, beams and girders, tied into primary structure such as the house sides, hull side, hull bottom, and adjacent underlying bulkheads. Usually, reinforcement of the house or deck sheathing and additional heavy steel plates and inserts are also required.
The safe operation of a crane is not only reliant on adhering to its design limits but also the way in which the crane is installed on the vessel. The only way to determine the safe installation of a crane is to complete an engineering analysis so suitable installation drawings can be provided and a safe working load limitation identified. Not following the installation recommendations and load limitations could lead to a crane failure, which could lead to damage to the crane, vessel, the lifted item, and more seriously, injury or death to persons in the way of the crane.
Before proceeding with any crane or other lifting appliance installation, it is strongly recommended to contact a qualified engineering consultant for proper guidance and advice. Although an engineering analysis can be costly, it is a great investment when compared to the alternative.
