Selection
Mooring Tail Selection Guide
6 min read
A tail is a deliberate weak-and-elastic section at the ship's end of a low-stretch mooring line. Understanding why it exists makes specifying it straightforward.
What the tail is for
Low-elongation main lines — HMPE especially, wire even more so — transmit movement almost instantly as load. A vessel at a berth is never still: surge, passing ships, tide and cargo operations all move it. Without elasticity somewhere in the system, that movement becomes a series of sharp peak loads on the winch, the bitt, the fitting and the rope itself.
The tail reintroduces elasticity in a short, replaceable section that is easy to inspect and cheap to renew compared with the main line.
Why nylon
Nylon (polyamide) has the highest elongation of the common mooring fibres, which is exactly the property the tail needs. Polyester tails are used where less elasticity is wanted or where nylon's loss of strength when wet is a concern. Polypropylene is not appropriate for tails in demanding service.
Strength relationship with the main line
The tail's break force must sit in a defined relationship to the main line's LDBF — set out in the vessel's mooring management plan rather than chosen by the purchaser. A tail that is too weak becomes the routine failure point. A tail that is too strong defeats its purpose and shifts overload back into the main line and the ship's fittings.
This is a specification to be read from the vessel's documentation, not estimated. Send it with the enquiry.
Length and connection
- Tail length follows the mooring arrangement and the fairlead-to-bitt geometry
- Connection method must match what the vessel actually uses — cow hitch, shackle, or a proprietary link
- The connection is a wear point and must be inspected as carefully as the tail itself
- Eye size at each end must be specified separately; they are frequently different
Inspection and retirement
Tails work harder than the main line by design — they take the cyclic elongation. They therefore reach retirement sooner and should be tracked as separate items in the line record, with their own service dates and inspection history, not treated as an accessory of the main line.
Frequently Asked Questions
- Tails are used with low-elongation main lines, particularly HMPE and wire, and where terminal or vessel requirements call for them. A nylon main line already has elasticity and does not need one for the same reason.
Need this applied to your vessel?
Send us the ship design MBL, the required diameter, construction and length, the delivery port and the date. We will come back with a line configuration and the documentation it will carry.
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