Mooring Tails Explained: Materials, Length, MBL & When They’re Required Mooring / Commercial marine / Technical guide A mooring tail is the short, elastic length spliced between a stiff mooring line and the ship — and on most tankers it isn’t optional. Here’s what it does, how it’s sized, and when OCIMF rules make it a requirement rather than a choice. Technical figures in this guide are drawn from OCIMF’s Mooring Equipment Guidelines (MEG4) and published manufacturer technical guidance — see references below.