Think you know how deep your crankbaits run? Odds are, you don't. Some lure makers provide fairly accurate depth ranges for their crankbaits; others lead you astray.
And while crankbaits with bigger bills generally run deeper, the difference may not be as substantial as you think. A crankbait's overall design, in addition to the size of its bill, determines its maximum depth. You must also take into account the line size, casting distance and rod position during the retrieve, all of which significantly influence a crankbait's depth.
Sadly, the running depths of some crankbaits have been deduced by little more than hocus-pocus. This is no longer true, thanks to the spiral-bound Precision Casting guide by Dr. Steven Holt and Mark Romanack, which contains precise diving charts for 123 popular crankbaits.
Each chart reveals how deep a particular crankbait dives when cast 40, 70 and 100 feet with monofilament lines that test 8, 10, 12, 14, 17 and 20 pounds. The chart also reveals each crankbait's diving curve and maximum depth range, using a 70-foot cast with 14-pound line as a baseline. In addition, the guide's introductory section offers hard evidence that debunks many crankbait theories and provides information that will help you put crankbaits in the strike zone.
Making the guide
When compiling data for Precision Casting, Holt and Romanack drew on what they had learned while preparing their Precision Trolling guide, introduced in 1991. The trolling guide, geared to walleye anglers, received top priority because Holt and Romanack regularly compete in walleye tournaments. They were painfully aware of how badly information was needed on the actual running depths of trolled crankbaits.
Precision Trolling quickly became an essential tool for serious walleye anglers everywhere. It has been expanded to the point where it now contains 179 dive curves in the sixth edition.
"Few bass fishermen troll, of course," says Holt. "But we knew bass anglers would benefit from casting charts that take the guesswork out of crankbait fishing. We tested the most popular bass crankbaits from a cross-section of manufacturers."
Holt is uniquely qualified to conduct such tests. He is an Emergency Medicine and AeroMedical specialist with a background in engineering sciences, hence his sharp, analytical mind. He is also a veteran fisherman and advanced scuba diver, attributes that also come into play during the testing process. Romanack, an avid angler and outdoor writer, has the ability to present technical information in an easy-to-grasp format.
Casting data proved more difficult to obtain than trolling data. For the trolling charts, the only measurement necessary was the crankbait's running depth at a specific speed, with different lengths of line. This was accomplished by having Romanack troll past a buoy, from which hung a metered pipe. Beneath the surface in scuba gear, Holt noted the exact depth at which the crankbait passed the pipe.
"It is crucial to actually see the lure when taking these measurements, whether trolling or casting," says Holt. "From the surface, you can't always tell when a lure is tracking slightly off to one side. But this is readily apparent underwater. If a faulty crankbait can't be tuned to run true, it is discarded."
Casting test apparatus
To decipher an accurate diving curve for crankbaits, Holt and Romanack decided that the crankbait's depth should be taken every 10 feet throughout the retrieve. It took them a year to come up with a reliable procedure for measuring the dive curve, and two more years to collect the data for Precision Casting.
One of their failed test procedures consisted of a series of metered pipes anchored in 5-gallon buckets filled with cement. Theoretically, the buckets could be set on the bottom in a straight line at 10-foot intervals, and the crankbaits run alongside the pipes. But when the heavy buckets were set on bottom, they stirred up clouds of lingering silt that made it impossible to get accurate readings. Since the tests were done on public waters, the buckets could not be set out overnight. So much for theory.
While driving to work one morning, a "Eureka" moment slapped Holt with the solution: tether balls. A tether ball, which is similar to a volleyball, comes with a loop that attaches to a length of rope, which, in turn, is attached to a post. It is game played mainly by children.
The test apparatus consists of 11 tether balls fixed to 100 feet of rope at 10-foot intervals. The rope is held taut by anchor lines that extend well out of the cranking zone to prevent silt from clouding the diver's vision. A 25-foot length of PVC pipe, marked and labelled at 6-inch intervals, comprises the measuring device.
Test procedure
Most lures are cast with the same 6-foot Quantum Tour Edition baitcasting rod and reel and 14-pound monofilament. Light lures that cannot reach 70 feet with baitcasting tackle are cast with a Quantum Tour Edition spinning outfit with 14-pound-test line.
Romanack anchors his boat so the bow holds smack on the zero ball. Holt starts with the measuring pipe hanging from the 60-foot tether ball.
Romanack then casts 12 times to the 70-foot tether ball and retrieves the crankbait while Holt measures the depth of the lure as it swims past the pipe at 60 feet. The highest and lowest numbers are thrown out, and the remaining 10 measurements averaged. This process is repeated at every tether ball from 50 to 10 feet to generate the 70-foot diving curve.
All testing is done early in the morning, before boat traffic and air movements roil the surface. The water must be absolutely flat, because bouncing tether balls alter the readings. Any crosswind pushes a bow in the line of tether balls. Wind also hinders casting accuracy.
"Even a slight breeze pushes a crankbait well off target with a 70-foot cast," says Romanack. "It is imperative that the lure begin diving right next to the 70-foot ball. If it is a few feet too close or too far, it changes the measurement. My casting ability improved significantly while performing the tests. It had to."
When testing, a short cast was a wasted cast. A long cast with a floating lure was no problem, because the crankbait could be slowly wound even with the 70-foot tether ball before beginning the retrieve. This was not possible with suspending crankbaits, which hover below the surface when pulled ahead. Suspending lures provided the greatest challenge, since the casts had to be dead-on target.
Casting distance
Holt and Romanack settled on the 70-foot distance for the diving curve after conducting a backyard test with 10 of their fishing buddies. Each of the anglers was asked to make 50 comfortably long casts with an identical baitcasting outfit and a 3/8-ounce Wiggle Wart. The distance of each cast was measured, and the measurements were averaged. The test concluded that 70 feet was close to the average casting distance.
In addition to the 70-foot diving curve, Holt and Romanack wanted to provide the maximum depths crankbaits would reach with 40- and 100-foot casts, as well as how deep the lures would dive when cast 40, 70 and 100 feet with lines ranging from 8- to 20-pound test. They also wanted to conduct tests that would reveal the impact of retrieve speeds and rod positions on crankbait depths.
To test every lure with all these variables would have been an overwhelming task. A reasonable alternative, believed Holt and Romanack, was to compile a group of 10 test lures that varied in brand, size and depth. This group of lures was run through a more extensive series of tests to provide a basis from which to extrapolate the performance of all the lures in the Precision Casting guide.
In terms of casting distance, the group of test lures demonstrated that a given crankbait runs about 25 percent shallower on a 40-foot cast than on a 70-foot cast. A 100-foot cast allows the crankbait to dive 15 percent deeper than a 70-foot cast.
Line size
A given crankbait runs approximately 20 percent deeper with 8-pound-test monofilament than with 14-pound test. On 20-pound test, the crankbait runs 10 percent shallower than on 14-pound test.
"The line diameter and the distance of the cast are the two primary factors that influence a crankbait's diving depth," notes Romanack. "If you want a crankbait to get deeper, switch to lighter line. Thinner line casts farther, which also increases the depth."
Retrieve speed
Retrieve speed has a negligible impact on a crankbait's depth. This finding did not surprise Holt and Romanack, because they had already noted it while conducting tests for their trolling guide.
The standard retrieve speed for the casting tests was a "comfortable" rate, with a 5.1:1 ratio baitcasting reel. When testing for the influence of retrieve speeds, Romanack cranked barely fast enough to make the lure wobble, and also as fast as he could physically reel, or as fast as the lure would run without tilting or rolling.
"We could demonstrate no significant difference in maximum running depths with different retrieval speeds," says Romanack. "It seems that any increased diving forces on the lure associated with increased speed are offset by equally increasing upward forces of line resistance or drag."
Rod position
Missourian Paul Elias, a veteran of many BASS wars, claimed years ago that you could increase a crankbait's depth by jamming the rod into the water while retrieving. Some anglers ridiculed Elias when he introduced the laborious, backbreaking tactic known as the kneel-and-reel. It appears Elias was right. Holt and Romanack's testing shows that the kneel-and-reel is just as effective as Elias said it was.
"No doubt about it," says Romanack. "For every foot you shove the rod tip into the water, you gain about a foot of depth with a crankbait."
Raising the rod tip above the water also affects a crankbait's depth, but not as dramatically as the kneel-and-reel. For every 3 feet you raise the rod tip, you decrease the crankbait's depth by about 1 foot.
"The information in Precision Casting won't do much for casual bass anglers who fish mainly to relax," says Romanack. "Only serious fishermen who want as much control over their lures as possible will fully take advantage of the guide."
