If you ever have to pull hard on a wire, as one would if one was driving a tug and towing something, you’ll need to know just how far you’ve sagged so to speak. The towing fraternity likes to refer to this wire sagging malarkey as ‘catenary’. Indeed it is a nicer word, less ‘Carry On’ and more ‘Lloyds List’, so to speak.
To calculate the catenary please find the following spreadsheet, purloined if I remember correctly form my ‘Maersk Anchor Handling Manual’. A very useful book indeed. Just enter the wire diameter in millimetres into F1 and prepare to be amazed.