The rig is fished as the snood from a pulley rig and can be clipped down for casting. The hook is tied to the end of the snood line using the knotless knot, which can been seen here, with a length of line left below the hook to attached the swivel. The hook size should match the size of the bait.
The swivel should be positioned 25 to 30 mm below the bend of the hook and a short length of line attached to the free side. This is used to simply tie around the hardback crab using granny knots. It stands up well to casting with one particular crab last year being launched out five times before it succumbed to a hungry hound.
The crab could be tied directly to the spare end of the knotless knot but this would mean having to use a fresh snood every time the bait was changed. Using Graeme's method only the short length of crab tying line needs to be replaced. An added advatage is that hardback shore crabs are much easier and cheaper to locate than their peeler relatives. There is no reason why this rig could not be used with hermit crabs or prawns as an alternative to the crabs.
An alternative that Graeme is testing is to replace the swivel with a Gemini clip and the crab wrapped in a rubber band. There are plenty of other ideas from the freshwater branch of our sport which translate well when used in the sea, it just needs innovative anglers to think out of the box and be willing to give them a try.