Choosing the right swivel means examining the type of fishing you'll be participating in. Offshore trolling is perhaps the most strenuous and requires the absolute best components. For our serious trolling endeavors we turn to stainless steel ball bearing swivels with two welded rings - sometimes with a snap on one side. This type of swivel is ideal for trolling because the double rings give the connection more distance to rotate and yet still stay in balance which ultimately reduces resistance and eliminates line twist.
Under minimal load, a barrel swivel should perform to spec. However, when sized inappropriately or subjected to heavy load (e.g., trolling deep-diving plugs, lengthy or repeated battles with big fish, soaking baits in a strong current), the friction within the swivel will slow or halt its rotation. When this happens, the swivel will fail to perform its job and allow twists to travel up the fishing line.