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Apr1-12, 02:54 PM
P: 10
Hi Waled Gaber,

The crane is used on a ship that assists cutter and suction hopper dredgers, so the boat and cranes go anywhere the ships go. This is indeed usually in coastal and harbour regions, but the occasional tanker that passes by, can lead to bigger waves, and bigger dynamic loads on the crane. So I do need to introduce some kind of dynamic factor. I was looking in Lloyd's Register's Code for lifting appliances, and they indeed make a clear distinction between offshore cranes and shipboard cranes in harbours.
However, since the crane was designed for harbour conditions, and damage still occurs a bit too frequent, I was going to take a look at factors used in offshore industry for crane derating and use those for inspiration.

HEILA indeed recently introduced AHC and ways of visual and auditory overload feedback on their new crane models. The old ones aren't as 'smart' however. I'm sure they would provide retrofits as well, but unfortunately their company dodges every email or phonecall I make :)

In the end, we're probably just going to fit the crane with a load moment indicator and derate it using the ship's motions and the sea states... If you've got any experience in this field, or information, feel free to share :)