Calculating how much rope you need for guying any sort of antenna mast can be a fiddle - so I wrote a spreadsheet to help us. If you find a mistake, let me know!
https://mega.nz/folder/hq4mGY7Z#fSPzKPMhLIGmTnxUewZl1w - Here's link
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https://www.youtube.com/watch?v=DG4XtzSNy9c