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Mark's Mailbag - Common Questions at Precision Trolling Data, LLC

Mark's Mailbag are occasional posts to the blog in response to questions people submit on the Fishing 411 website.  Mark personally responds to the question and when relevant, we repost his answer here.  If you have a question you would like to ask Mark, please visit us at

Travis writes:  I have just purchased the lifetime version of your precision trolling app. I was under the impression that along with all of the crankbaits listed that there would be more line diameter options as well as line types. Also, different options for trolling speed. I'm not sure what speed you based the data provided is. For the most part this should be a good investment, just wondering if any of the info I'm asking for is or will be provided. Thank you.

Mark Replies:  Travis,

Your purchase of the Precision Trolling Data app is indeed a good investment. Literally hundreds of lures and trolling devices have been tested and the respective diving depths documented by our team using scuba diving methods to test, confirm and document every data point. 

Your first concern about trolling speed is a common one. Actually when trolling floating/diving style crankbaits trolling speed has little or no influence on how deep the lure actually runs. Most anglers mistakenly think that as they speed up the lure dives deeper because they can feel the bait working harder. Actually the bait is working harder and trying to dive deeper, but at the same time increased friction on the fishing line negates any additional depth. 

That stated we test our floating/diving crankbaits at about 2.0 to 2.5 MPH which is an average trolling speed. We also maintain that trolling speed throughout the entire testing process.

Trolling speed does however play a major role when dealing with sinking or negatively buoyant devices like lead core line, snap weights, keel sinkers, Tadpole Divers, etc. In the case of these devices we post the trolling speed right on the app and we use GPS technology to accurately maintain a trolling speed throughout the entire testing process. Also, in many cases we test at multiple trolling speeds to provide the maximum amount of trolling data.

As for line diameter options, the vast majority of our devices are tested on at least two line types and diameters such as .013 monofilament and 10/4 Fireline. Others are tested on line types or diameters ideal for using these respective devices. For example, the diving planers are typically tested on a 30# test super braid. It’s also important to note that 
.013 monofilament is about the same diameter as most 40# test super braids, further giving anglers line options in which to fish without compromise to our depth data.

It simply isn’t possible to test every lure on every line diameter and type. The data you have in your app has taken over 20 years to collect and the process never ends. Every summer we test new lures and diving devices in an effort to expand the wealth and value of the Precision Trolling Data app. While we would love to test every line diameter, that would require an army of scuba divers to accomplish and all that data would be overwhelmingly difficult to manage and display on a device like an app. Our goal is to provide anglers with as much data as practical and to make sure the data we provide is rock solid accurate.

Morris Langworth, the Precision Trolling Data, LLC head diver has thousands
 of hours of open water diving experience. The high level of skill that Morris 
provides as a scuba diver allows Precision Trolling to accurately document the 
diving depths of crankbaits and a wealth of trolling hardware.
It might help you to also know that years ago we did a line conversion chart for our Precision Trolling books. That chart confused more people than it helped because the fishing tackle industry had and still has no standards for line diameter to break strength ratios. In effect, a line conversion chart would be little more than “ball parking” the diving depth and here at Precision Trolling Data we strive to provide the most accurate data possible. 

I can tell you that for every line diameter you go up or down, the amount of influence on the maximum diving depth of a typical lure is less than two feet. In other words if you fish 12# test instead of the .013 10# we test on you are only losing about two feet of diving depth when the lure is fished on the longest practical lead lengths. In other words, line diameter isn’t the most profound variable influencing the diving depth of lures. Actually lead length is the big factor in determining diving depths of lures and that is precisely why we pay exceptionally close attention to managing our lead lengths on everything we test for Precision Trolling Data.  

Thanks again for purchasing the Precision Trolling Data app and I hope I answered your questions.

Best fishes,

Mark Romanack, Co-Owner
Precision Trolling Data, LLC