CHOOSING THE CORRECT ANCHOR
So you have been tasked with designing a mooring system for an offshore installation? Do you know which anchor is going to be best suited for the job? And what about any considerations you must take into account to reach the right decision?
Not all anchors are suited to all applications: although some are more versatile than others, there are some which simply will not work in certain environments. To help ensure that you make the best selection, there are some key factors you must consider when selecting an anchor:
– What is your mooring depth?
– Do you know your seabed condition?
– How large is the moored vessel?
– Is this an offshore or inshore mooring?
– Are you mooring alongside a quay?
These are all very important questions to pose when selecting the correct anchor. Only when you know all this information as a base point, can you then make an educated decision on what mooring system is to be used.
Assuming that you are not mooring alongside, in which case your options become lessened, probably the most versatile and widely used anchors is the “Drag Embedment Anchor”.
These anchors come in a range of sizes, from small 1 tonne units, to bespoke 50+ tonne anchors which can also be ballasted with concrete to provide additional holding power. Drag anchors can also be optimised by changing the angle of the “fluke”, where the fluke is the bit that does the digging, like a shovel. This ensures that the anchor embeds itself correctly in the seabed and reaches the desired depth – which is paramount in ensuring the anchor does not slip during operations. Alternatively, if the fluke is not set to the correct angle, you risk the anchor not embedding at all and simply skidding across the seabed – incurring cost and time delays in resetting.
There are a lot of anchoring options available on the market, however, following a structured list of considerations such as this will ensure that you make the right choice.