Use of stoppers
Where fitted, mechanical topping lift stoppers should be used. Where chain stoppers are used, they should always be applied by two half-hitches in the form of a cow hitch, suitably spaced with the remaining chain and rope tail backed round the wire and held taut to the wire.
A chain stopper should be shackled as near as possible in line with the span downhaul and always to an eye-plate, not passed round on a bight, which would induce bending stresses similar to those in a knotted chain.
No stopper should be shackled to the same eye-plate as the lead block for the span downhaul; this is particularly hazardous when the lead block has to be turned to take the downhaul to the winch or secure it to bitts or cleats.
The span downhaul should always be eased to a stopper and the stopper should take the weight before turns are removed from the winch, bitts or cleats.