The Baitcasting reel or revolving-spool reel, like the conventional reel, is a multiplying reel – that is to say that the line is stored on a bearing-supported revolving spool that is geared so that a single revolution of the crank handle results in multiple revolutions of the spool. The bait casting reel is mounted above the rod, hence its other name given to it in New Zealand and Australia, the overhead reel. The baitcasting reel dates from at least the mid-17th century, but came into wide use by amateur anglers during the 1870s. Early bait casting reels were often constructed with brass or iron gears, with casings and spools made of brass, German silver, or hard rubber. Featuring multiplying gears ranging from 2:1 to 4:1, these early reels had no drag mechanism, and anglers used their thumb on the spool to provide resistance to runs by a fish. As early as the 1870s, some models used bearings to mount the spool; as the free-spinning spool tended to cause backlash with strong pulls on the line, manufacturers soon incorporated a clicking pawl mechanism. This 'clicker' mechanism was never intended as a drag, but used solely to keep the spool from overrunning, much like a fly reel. Baitcasting reel users soon discovered that the clicking noise of the pawls provided valuable warning that a fish had taken the live bait, allowing the rod and reel to be left in a rod holder while awaiting a strike by a fish.
Most fishing reels are suspended from the bottom of the rod, since this position requires no wrist strength to overcome gravity while enabling the angler to cast and retrieve without changing hands. The baitcasting reel's unusual mounting position atop the rod is an accident of history. Baitcasting reels were originally designed to be cast when positioned atop the rod, then rotated upside-down in order to operate the crank handle while playing a fish or retrieving line. However, in practice most anglers preferred to keep the reel atop the rod for both cast and retrieve by simply transferring the rod to the left hand for the retrieve, then reverse-winding the crank handle. Because of this preference, mounting the crank handle on the right side of a bait casting reel (with standard clockwise crank handle rotation) has become customary, though models with left-hand retrieve have gained in popularity in recent years thanks to user familiarity with the spinning reel.
Many of today's baitcasting reels are constructed using aluminum, stainless steel, and/or synthetic composite materials. They typically include a level-wind mechanism to prevent the line from being trapped under itself on the spool during rewind and interfering with subsequent casts. Many are also fitted with anti-reverse handles and drags designed to slow runs by large and powerful game fish. Because the baitcasting reel uses the weight and momentum of the lure to pull the line from the rotating spool, it normally requires lures weighing 1/4 oz. or more in order to cast a significant distance. Recent developments have seen bait casting reels with gear ratios as high as 7.1/1. Higher gear ratios allow much faster retrieval of line, but sacrifice some amount of strength in exchange, since the additional gear teeth required reduces torque as well as the strength of the gear train. This could be a factor when fighting a large and powerful fish.
Spool tension on most modern baitcasting reels can be adjusted with adjustable spool tension, a centrifugal brake, or a magnetic "cast control." This reduces spool overrun during a cast and the resultant line snare, known as backlash, colloquially called a "bird's nest" or "birdie". This backlash is a result of the angular momentum of the spool and line which is not present with a fixed spool or spinning reel. Each time a lure of a different weight is attached, the cast control must be adjusted for the difference in weight. The bait casting reel design will operate well with a wide variety of fishing lines, ranging from braided multifilament and heat-fused "superlines" to copolymer, fluorocarbon, and nylon monofilaments (see Fishing line). Most bait casting reels can also easily be palmed or thumbed to increase the drag, set the hook, or to accurately halt the lure at a given point in the cast.
Baitcasters are known as multiplier reels in Europe, on account of their geared line retrieve (one turn of the handle resulting in multiple turns of the spool). Two variations of the revolving spool bait casting reel are the conventional surf fishing reel and the big game reel. These are very large and robust fishing reels, designed and built for heavy saltwater species such as tuna, marlin, sailfish and sharks. Surf fishing reels are normally mounted to long, two-handed rods; these reels frequently omit level-wind and braking mechanisms in order to achieve extremely long casting distances. Big game reels are not designed for casting, but are instead used for trolling or fishing set baits and lures; they are ideal for fighting large and heavy fish off a pier or boat. These reels normally use sophisticated star or lever drags in order to play out huge saltwater gamefish.
- Baitcasting Reel Operation
To cast a baitcasting rod and reel, the reel is turned on its side, the "free spool" feature engaged, and the thumb placed on the spool to hold the lure in position. The cast is performed by snapping the rod backward to the 2 o'clock position, then casting it forward in a smooth motion, allowing the lure to pull the line from the reel. The thumb is used to contact the line, moderating the revolutions of the spool and braking the lure when it reaches the desired aiming point. Though modern centrifugal and/or magnetic braking systems help to control backlash, using a bait casting reel still requires practice and a certain amount of finesse on the part of the fisherman for best results.