Understanding Large-Arbor Reels

Not all large-arbor reels are created equal. Consider all the factors before choosing a model that's right for you.

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So, you're considering getting a large-arbor reel, thinking that the faster retrieve and more consistent drag makes it just the ticket for handling long-running species such as bonefish, false albacore and blue-water thoroughbreds. But you hesitate, also having heard that all a large-arbor does is reduce backing capacity. What do you do?
To answer that, let's look at some of the characteristics of large-arbor reels.

Rate of Retrieve
Rate of retrieve, the major selling point of a large-arbor reel, is a function of the diameter of the reel spool. Let's define a standard-arbor reel as one with a spool arbor or hub approximately 1 inch in diameter. On such a reel, if the spool has only a few wraps of backing on it, one revolution of a (non-multiplier) reel will retrieve little more than 3 inches of line. (Remember your high school geometry?) Conversely, let's say a large-arbor's diameter has been increased to 2 inches. With this one change in the reel, you're able to crank in line at almost 6.5 inches per revolution with a similarly almost empty spool. Twice as much is 100 percent more line - on every crank!
During a fight, the rate of retrieve becomes a function of the diameter of the portion of the spool filled with backing and line. Since the effective radius of the spool increases or decreases as the line comes in or goes out, the rate of retrieve increases or decreases as well.
Increasing the arbor diameter only will do nothing to change the rate of retrieve with a full spool since the overall spool diameter hasn't increased. Instead, it will serve only to decrease the usable capacity of the reel. If, however, we increase the arbor of a reel and the overall spool diameter, we will increase the retrieval rate at both near-full and near-empty spool situations without losing capacity. Well-designed large-arbor reels, with both larger arbors and overall diameters, both increase the rate of line retrieval and retain sufficient backing capacity.
The change in effective diameter and rate of retrieve is more than a two-dimensional problem, however. Since fly lines and backing occupy space, we're really dealing with a three-dimensional issue. This third variable, the width of the spool, affects rate of retrieve as well.
Harking back to that geometry book, realize that a reel spool is simply a short cylinder turned on its edge, with a second cylinder, the hub or arbor, inside the first. Think of a doughnut. The hole is equivalent to the reel hub (arbor), and the edge of the doughnut is the outer edge of the spool. The actual edible part (let's call it "goody") is equivalent to the useable space on the reel spool, or volume. The amount of goody can vary by changing any of three dimensions. If we increase only the hole or arbor diameter, we have less goody. If we increase the outer diameter, we have a larger doughnut and thus more goody. Finally, if we increase the width, we have a fatter doughnut, and thus more goody. Obviously, the dimensions of each can be varied simultaneously to achieve a reel maker's specific requirements.

Crank It In
Large-arbor reels have a related benefit that's not talked about much, and that's cranking speed - how fast you can actually turn the reel handle. This is a two-part story. First, you can turn your hand in smaller circles faster than in larger circles, since you're "covering less ground" - you simply don't have to move your hand as far. Thus, while a smaller-diameter reel may not retrieve as much line per revolution, if we can crank in line at higher rpm, we're narrowing the presumed advantage of large-arbor reels. True, but - and here's the second part - turning your hand in those little, fast circles is considerably more tiring than turning them in slightly larger, albeit slower, circles. So when retrieving copious quantities of string, the large-arbor reel is a definite advantage. At least that's been my experience.
There is a middle ground that some large-arbor-reel makers have taken, and it perhaps represents the ultimate compromise. On these, the handle has been moved inward slightly toward the spool center. The angler then has a slightly smaller cranking radius, not so small as to tire out the hand, but not so large as to necessitate lazy, slow circles either.

Drag Consistency and Control
This time, get out your physics book. Remember that the longer a lever, the easier it is to lift a load? Conversely, the shorter the lever arm, the more effort that's needed to lift a similar load. Drag pressure is a similar linear function.
Say we have a large-arbor reel with a 5-inch diameter, and a standard-arbor reel with similar capacity (and similar width) with a 3-inch diameter. If each has enough line/backing removed to reduce the filled spool diameter by 2 inches, the large-arbor reel diameter will go from 5 inches to 3 inches, a 40-percent decrease. The standard reel diameter will go from 3 inches to 1 inch, for a significantly greater decrease of 66 percent. The fish, initially pulling 3 pounds of drag off each reel, will now be pulling against approximately 5 pounds of drag off the large-arbor reel, and a whopping 9 pounds against the standard-arbor reel.
In addition to maintaining a more consistent drag pressure, large-arbor/large-diameter reels offer better fighting control simply because the spool is turning more slowly than a standard-arbor reel with similar capacity and diameter. The angler is better able to palm a slower-turning reel that, combined with the more consistent drag pressure, improves the chance of landing a fish.
Line "Memory"
Line memory, all too apparent when line is first stripped off the reel onto the boat deck coiled like a kid's Slinky, is a nuisance. The increased diameter of a large-arbor reel does reduce the coiling effect, or at least the coils are larger in diameter. But with today's fly lines - assuming they're matched to their intended climate - it usually only takes one good stretch to remove the coils. Reducing line memory ranks as a real, but minor, benefit in my opinion.

Convertible Reels
Convertible reels represent a tricky subject. They are reels that will interchangeably hold either a standard-arbor spool or a large-arbor spool, and are touted as "dual-purpose" reels. A typical configuration will offer a single frame with two interchangeable spools - a large-arbor spool suitable for bonefish, redfish or stripers (WF-8 + 200 yards of 20-pound backing), and a standard-arbor spool suitable for tarpon or offshore game fish (WF-12 + 300 yards of 30-pound). Sometimes this works, sometimes not.
In this case, the reel provides the fast retrieve of a large-arbor in the bonefish configuration. But what about its weight: Is it as light as a bonefish reel or as heavy as a tarpon reel? And in tarpon configuration, the capacity is there, but the reel is simply in a standard arbor configuration. There are some really good combinations (some of the Abels and Charletons come to mind), but again, you have to play the numbers game, comparing capacity, diameter and weight.

Disadvantages
In my opinion, there are no real disadvantages to a large-arbor reel. Certainly, if we increase the size of a reel, enlarging both the arbor and the overall diameter of the reel, that reel will be heavier. However, judicious paring of weight can produce a light but strong reel.
Similarly, the point can be made that a larger-diameter reel places more of the reel's weight further away from the axis of the rod, resulting in a more tiring combination to cast. I've found this to be true more in theory than in practice, and will gladly take the increased pickup over this "swing" effect.

Choosing
The overriding reason to choose a large-arbor reel for saltwater fly fishing is to take advantage of the enhanced speed of line retrieval. Having more consistent drag pressure is a nice feature, but with experience, one can adjust the drag when needed. It's hard to compensate for speed, though. To gain maximum retrieval, get the largest arbor, largest outside-diameter reel you can find that provides the desired line/backing capacity. But - don't forget that larger is heavier. Unless you're built like Popeye, you don't want a 16-ounce reel "balancing" your 8-weight rod. Picking the right large-arbor requires that you select the best "balance" of retrieve rate, capacity, weight and other important reel features. Bigger is better, if chosen wisely.