At its most basic level, a fishing rod is merely a second-class lever used to hoist a fish out of the water. A rod works under two opposing forces, one pulling down at the end of the rod and one pulling up where the fisherman's hands grip the pole. The fulcrum for the lever, around which the rod rotates, is the point where the rod is jammed into the fisherman's groin or belly. Because of the leverage, a fish feels much heavier suspended from the end of a pole than hanging directly from a length of line. A cane pole or its modern-day (often telescopic) counterpart, made from fiberglass, does a great job of lifting small fish.
If you put a fishing reel on the pole near the rod's butt section, the rod still acts as a second-class lever but now becomes a tool that can pull much bigger fish closer to the angler so he can recapture line. Again, because of the leverage generated against the fisherman, the longer the rod or pole, the harder it becomes for the fisherman to lift a fish of a given weight clear of the water, or pull it closer to the boat.
The tip of any rod, even a cane pole, will bend under pressure. This creates an additional function where the rod tip acts as a shock absorber. Tips can flex faster than the reel can release line, therefore softening the effect of quick tugs or yanks that occur when a large fish jumps, shakes its head or tries to run away.
These two functions, shock absorption and lifting, represent the majority of a rod's usefulness - with one major exception. (See "Casting Rods," page 3)
I consider all line classes from 2- to 20-pound-test light tackle for pursuing billfish, with everything less than 12-pound considered ultralight. This coincides with the International Game Fish Association's rules that determine the allowable length of leaders and doubled lines.
Almost all light-tackle fish fighting is done standing up. When using light lines, the angler can choose between spinning reels or revolving-spool, conventional-style reels. In either case, the rods used by each are very similar, with one major exception: Line guides on conventional rods run along the top side of the rod, while the guides on spinning rods are attached underneath.
One of the major advantages of standing up with light tackle is the ability of the angler to move quickly around the cockpit. The angler can move from one side of the cockpit to the other and can even plunge the tip of the rod deep into the water to keep the line from coming into contact with the boat hull or propellers. With a skilled stand-up angler, an expert captain can aggressively maneuver the boat while chasing a fish in reverse or forward gear, and take more chances while trying to get the leader within reach of the deckhand.
Using the common rule of thumb of 25 percent of the line's breaking strain as a strike drag setting, we would start with 5 pounds of drag on 20-pound line and a miniscule 1 pound of drag on 4-pound line at the time of hookup. In these instances, it benefits the angler to use a long and flexible rod, which by using leverage, magnifies the perceived force that the fish exerts and makes it easier for the angler to feel even minute increases in tension on the line.
Hall of fame angler and rod builder Gary Loomis carried the idea of extra-long and limber rods to the extreme and invented the noodle rod. Loomis set numerous ultralight world records with these unusual rods. However, billfish anglers haven't adopted these extreme rods, due in large part to the difficulty in maneuvering such a long rod when the fish nears the boat and the wireman needs to reach out and grab the leader.
Medium Tackle: 30 to 50
Although I define 30- and 50-pound line classes as medium tackle, I sometimes include 20-pound line in this class. Late in a fight, expert anglers like Stewart Campbell can use at least 16 pounds of drag on the 20-pound class. You can do that much better (and for longer periods of time) when sitting in the chair. With 16 pounds of drag and a 7-foot overall rod length bending to a true length of six feet, when the angler holds onto the foregrip two feet above the bottom of the butt, he ends up holding 48 pounds without the aid of a harness (16 x 6 / 2 = 48). As you might imagine, it's very hard to hold 48 pounds with one hand for an extended period of time. This is why many less skilled anglers do not use anywhere near the drag their line can stand. The angler, not the line, becomes the limiting factor in how much drag can be used while standing up without a harness.