One of the first rules of fishing is simple: fish to the conditions
Which rig is best to use on the business end of the snapper line? Some people opt for a ledger rig, others prefer a trace. On some days one rig will outfish the other, but there are good reasons for this and it comes down to the conditions encountered - boat and water movement.
The dynamics of the actual trace-sinker setup can be altered to suit the conditions. For example, if the boat is swinging on the anchor a ledger rig with the sinker on the bottom under a couple of hooks on loops, or a pre-tied flasher rig, can be pulled up away from the bottom where the snapper are usually found. In this case a sinker above a swivel with a trace below and a hook on the end will ensure the bait stays hard on the bottom. The same applies in strong currents.
Conversely, when the surface is still and there is little current, a ledger will often produce better results. But the trick is to have the hooks as low as possible. When tying a ledger the bottom loop should be just above the sinker so the hook will droop down on to the bottom, and the next hook should be as close as possible without the loops being able to meet and tangle the hooks. The pre-tied flasher rigs with coloured flashers on the hooks often have the bottom hook too far above the sinker but this is easily remedied by using a sharp knife and raising the sinker.
The hooks on ledgers should be recurve hooks, while the common octopus or suicide models are usually tied on to the end of a long trace. The rule of thumb with a trace, or running rig, is "the stronger the current, the longer the trace".