The most asked question of a any one in the industry who makes a crankbait of any kind is likely to be "how deep does it run"? Lord knows I've been asked this question no less than a thousand times of my own DepthRaider series of crankbaits, and my answer is always the same – "it depends." A basic simple answer to this question is tough since a number of variables can effect the potential running depth of any crankbait; particularly floating divers, but most certainly sinking and suspending versions have some of the same issues, as well as some others specific to that particular lure category. First off, it's important to grasp some of the most basic factors that determine the running depth of a crankbait. They are as easy to remember as 1, 2, 3. 1) Line diameter, 2) line length, and 3) retrieve or trolling speed.
Visualize, if you will, attaching the deepest diving crankbait in your tacklebox to your anchor or mooring rope. Now, imagine letting out 50 feet of this rope, attaching it to the back end of your boat and beginning a straight trolling pass. How deep do you think this lure is going to dive with that thick diameter rope? Obviously, not very deep at all. Conversely, attach that same crankbait to an equal length (50 feet) of sewing thread and make the same trolling pass again. Do you think this lure will dive any deeper? You bet it will. Of course, this is an exaggeration, but is essentially describes the importance of line diameter in this equation.
Now, of course you'd never fish a crankbait on a thick piece of rope, nor the ultra-thin spool of sewing thread, but the basic idea here is to understand line drag and resistence to water.. Plainly put, the thicker the diameter of the line you choose to fish on any given crankbait, the shallower that lure will run. Thicker diameter lines capture more water, and therefore create more drag. This resistance or line drag pulls the lure upwards, reducing its overall diving range. The thicker the line, the more drag is created, and the shallower the lure will run. I just cited an exaggerated example, utilizing an anchor rope versus sewing thread, but subtle variances in depth diving performance exist in real fishing situations with various line tests on your present musky rod & reel outfits.
Basically, if you want to increase the running depth of your lure, you'll need to drop down a notch or two in line size. And when I speak of line size, I'm talking about line diameter more specifically. On the flip side, if you need a favorite lure to run a bit shallower, use a heavier weight line – a line of larger diameter. Subtle diving differences of one to two feet are easily attainable by switching line sizes. For example, a popular deep diving musky crankbait that dives to six feet on an normal length cast of 60 to 75 feet with 80 pound test Superbraid, will likely dive to eight feet with 65 pound test with the same cast length. This is precisely what happens when you switch an original 100 series DepthRaider from one rod (containing the 80 lb. Test) to another (containing the 65 lb.).
In the musky crankin' world, it's also important to note that there are many situations where you do not want the lure to dive too deep. This is not always desirable. A lure that dives too deep over top tall weeds, for example, is going to plow weeds instead of skimming over them. A lure that dives too deep overtop a shallow cresting rock hump is more likely to snag up in rock crevices instead of occasionally careening off the rocky projections. A lure that dives too deep into sunken brush will hang up in the maze of branches instead of ticking the tops. Ideally, you want a lure that dives just barely deep enough. That is always more desirable in my book. This makes it much easier to keep it working cleanly.
Heavy lines can also work in your favor for other specific fishing situations. Topwater lures usually work much better on heavy gauge lines, for example. The added drag here keeps the line up reducing the line sinkage and making it easier overall to keep a lure up on the surface. In a sense, the thicker line improves the lure's buoyancy. A TopRaider, for example, works better on 80 lb. Superbraid than it does on 50 or 65 lb. This same philosophy works with shallow running subsurface lures like spinnerbaits and bucktails as well as crankbaits. If your primary targets are shallow, and you want a slower spinner presentation that still keeps the bucktail or spinnerbait shallow, heavy line is the better choice. Heavy line will also reduce the lure's descent or sink rate. This is something that jig fishermen need to consider all the time. Rig a jig on a heavy line and the sink rate or sinking speed decreases noticeably. This also comes into play when using a sinking count-down style crankbait. Your sink rate with a count-down will surely be noticeably faster with thinner gauge line than with a thick one.
Basically, this is one of the most basic fundamentals of being a good crankbait fisherman. Having the knowledge to adapt your tackle, most specifically the line, to the conditions at hand, in order to make the lure run the right depth is essential to success. This is only possible by first understanding the concept of what makes a lure run deep. Serious musky crankers know these simple secrets and make the whole system work wonderfully. The less experienced rarely catch on, miring in frustration instead, vainly attempting to work the deep diver overtop a grassbed only to be fouled on every other cast.
Thinner gauge lines also have their place in crankbait fishing, of course, and their purpose is often just the opposite. Thin lines cut through the water like a razor making the lure dive to its maximum depth potential. Combine this with a longer cast and the potential maximum running depth range increases even more.
If your crankbait appears to be hitting around 5 ½ to 6 feet with the 80 pound line, dropping down to 65 pound test may be necessary in order to effectively hit the 8 foot range for muskies in clearer waters. Drop down to 50 lb. braid and that same lure may reach the 10 foot mark - critical on some of the clearest lakes with deeper weed lines. In this case, 80 lb. line and a lure running only 5 to 6 feet deep is probably not going to be as productive. The closer you get to those deep weed edges, the more fish you're probably going to catch.
A close attention to tackle detail here is critical, and in this case, the line diameter is the key element to attaining just a couple more feet of depth. The astute crankbait fisherman always considers the line diameter and the way it effects running depth. Simply analyze how deep you think you need your crankbait to run, choose a lure that gets you in the ball park, and then play with various line diameters in order to get peak performance on every cast.
A less known aspect of line test selection is the variance in line diameters between equal test lines. In other words, not all 80 pound test lines are the same diameter. That's why you need to check the precise numerical line diameter on the package to compare. One manufacturer's 80 pound test might be the same diameter as another's 50 pound. A lot of this has to do with where the line is manufactured and the overall line composition. New line technologies and a variety of new fibers have created a line war of sorts making the issue of comparing line tests difficult. The only way to precisely get the desired performance you need and any kind of comparative analysis is to check the actual line diameter on the line package.
Cast length and/or trolling line distance is another factor that greatly effects true running depth. Shorter casts and/or shorter length of lines out on a troll reduce the running depth potential of almost any lure. Longer casts and/or more line out on a troll increase the depth running potential. Simply put, longer casts increase running depth. More line out on a troll increases running depth.
The underwater path of a deep diving crankbait on a short cast is somewhat "V" shaped. The underwater path of a deep diver on a long cast is more "U" shaped. In the casting world, a good of the retrieve is always taken up diving the lure down to its maximum level. If the cast is too short, the max. level might not be reached before a shortening line length from rod tip to lure actually begins forcing the lure back upwards.
The only way to assure maximum running depth on any deep diver is to pitch a long cast. A long cast provides enough distance between rod tip and lure for the bait to dig to its deepest potential. The longer cast also enables the lure to stay at the max. depth range longer before it is pulled upward. That's also why trolling takes a lure much deeper than casting. The length of line remains consistent on the troll giving the lure all the time needed to dig to its level-off point. The lure is never being pulled upward by a decreasing line distance on a troll. The line distance is steadily decreasing on any cast/retrieve situation.
In fact, a good rule of thumb on casting versus trolling is — trolling doubles the running depth. In other words, if a given crankbait runs 6 feet deep with 80 pound test on the cast, it will run 12 feet deep on the troll with the same line. This generally holds true for most lures, and is an important thing to know for any crankbait application. If you can't hit bottom on a potential hotspot with a cast, a follow-up trolling pass with the same lure will probably do it. The knowledge of this little known trick has really paid big dividends for me on muskies over many past excursions. I've taken lots of wallhangers on follow-up trolling passes after failing to get deep enough on the cast.
The actual type of line used also effects running depth to some degree, and in one instance greatly increases it. For example, braided lines drag slightly more water than monofilament and therefore pull a crankbait slightly shallower. If you used braided lines and monofilament lines of the same diameter on the same lure, the rod containing mono will make the lure dive slightly deeper. A sinking line like one of the new fluorocarbons will increase running depth even more.
Speed of retrieve or troll is the final factor in line depth attention. Generally speaking, faster retrieves make floating/divers dive deeper. Slower speeds keep floating/divers shallower. Crank a floating diver real slow and it stays right on the surface. Crank it fast and it digs downward. This basic concept works to a point, but there is a certain speed that each individual crankbait reaches where it destroys the lure's ability to dive and track. I like to call this the "torque-out speed". Few lures reach torque-out speed on a cast and retrieve, but many do on a troll. The outboard motor is certainly capable of pulling a crankbait at far higher speeds than any manual retrieve can. Therefore it's important to watch out for torque-out when trolling more than casting even though both can occur.
Too much speed also has a tendency to put so much drag between the lure, line, and rod tip that it can also reduce running depth. This is more common again with the troll than with the cast, but it can occur with a high speed reel and a small crankbait. Don't over crank or over troll smaller lures. Each lure has a perfect speed whether you are casting or trolling. That perfect speed makes the lure track true, and run down to its maximum depth. Any speed less than this reduces running depth. Any speed above this level will torque the lure out of track reduce its diving ability.
Sinking crankbaits do behave quite differently at slow speeds. Most noteworthy, the lack of buoyancy does not force them to rise, thus decreasing their running depth. Slower speeds may cause them to sink, thus increasing their dive. A great cold water presentation, for example, is to slowly crawl a sinking version crankbait deep along hard bottom pausing occasionally to allow the lure to sink back to the bottom. A thinner diameter line, by the way, makes this lure sink faster. A thicker gauge line might even make it suspend.
Line diameter and casting/trolling distance does indeed have a great influence on overall running depth of any given crankbait. Understanding the basic concept here is your first step in truly mastering the art of crankbait fishing. From that point on, it's a matter of learning the diving depth characteristics of each and every individual lure in your tackle box. The more you know about each lure's capabilities and how line diameter, casting distance or line length from rod tip to lure on a troll, and retrieve or trolling speed effect the performance of your crankbaits, the more muskies you're going to catch.