Rod Loading

• Rod loading is a concept borrowed from fly-fishing, but it very much applies to casting heavy bait. Fly-rods depend on a dynamic known as rod loading, by which the inertia and weight of the line, on a back-cast for example, bend the rod. When the rod bends, the energy from that weight is stored in the rod, just like like winding up a spring or setting a mouse trap. On the forward cast, you don't just use the mechanical motion of your arm, shoulder and body to cast; you take advantage of the energy stored in the bend of the rod. When casting heavy bait, you want a rod that takes advantage of the same dynamic.
  
  

Length

• It's easier to store a lot of energy in a long rod than in a short rod. You can see this in any bendable object. A thick piece of metal that's only six inches long, for example, may not bend at all, whereas the same material that's twenty feet long might be quite easy to bend. Rods are no different. Since energy is stored in the bend of the rod, and more energy can be stored in longer rods, longer rods are generally better for casting big bait.
  
  

Taper: Differential in Diameter

• Length isn't the only factor. If you try to cast a two by four, it won't bend at all. It might be long, but you won't be able to store any energy in it by bending it. To be able to both cast a rod and have a rod worthy of playing fish, you need a taper. Toward the butt the rod is stiffest; that helps you fight big fish. Toward the tip of the rod, it's more flexible; that provides a shock-absorber action that's also very important in fighting fish. The taper -- the rate per unit length at which the rod thins out, dictates the nature of the rod's loading characteristics. You want a taper that produces firm action and a quick release.
  
  

Rugged Tip

• Rod tips help you feel your line; they keep constant pressure on fish. They add subtlety. They also break. Rod tips are the most delicate part of the rod. So, for heavy-duty rods -- surf-casting rods, for example -- you want the heaviest tip you can find that has the strength to stand up to weighted baits.