RayburnGuy Posted November 17, 2010 Report Share Posted November 17, 2010 Has anyone tried using a side scanning sonar to determine the depth at which a crankbait is running? I don't have a side scan and not even sure if it's possible, but this is the type of thing that crosses my mind late at night and I just had to ask. Ben Quote Link to comment Share on other sites More sharing options...
BobP Posted November 18, 2010 Report Share Posted November 18, 2010 I have sidescan sonar and no, it won't help. There's no scaling for the sidescan info shown on the screen like there is for down looking sonar. The best I can suggest is determine the bottom depth on a regular sonar and see if you can bounce bottom with your crankbait. Of course, you have to have sonar that is correctly "offset" for the depth of your transducer and you have to trust that your sonar is fairly accurate. If you want real dope about crankbait depth, it's worthwhile to dispel a couple of myths. Here's some data from "Precision Casting" published in 2000, which did actual underwater tests of casting and crankbait performance over a measured course of distance and depth observed underwater by a diver: Many guys buy into the fiction that 4-5 cranks of the reel get a crankbait down to max depth. Not so. On a long cast, crankbaits reach their deepest beginning 30 ft from the boat, lasting until 12 ft away from the boat. This is very consistent across brands of commercial crankbaits and types of crankbaits (shallow-medium-deep runners) - consistent enough that you can ignore claims to the contrary. Guys also think (and you even hear pro tournament fishermen saying this) that a long cast is 75-100 yards. When actually measuring casts by a group of experienced bass fishermen, a "very long" cast is 100 FEET, and a typical "long cast" is 70 FEET - not YARDS. So on a long 70 ft cast, the crankbait is still diving through most of the retrieve, only reaching max depth after 40 ft of the total 70 ft retrieve back to the boat. You need to calibrate test results (and expectations) against reality, not advertising foolery. Quote Link to comment Share on other sites More sharing options...
spoonbender Posted November 20, 2010 Report Share Posted November 20, 2010 BobP makes some good points. I do a lot of controlled depth fishing and rely quite a bit on the books by Mark Romanack that contain the depths achieved specific to each lure. The info is only accurate for trolled lures, doesn't apply well to hand cast lures unless you can make the incredible long casts some dudes brag about. Retrieve speed, type of line used and rod tip placement affect your depth. I have a Raymarine side scan sonar but as the lures are typically so far behind the boat, don't register on the screen. Standard sonar registers the depth of our downrigger balls as deep as 250 ft. but thats a different subject. Quote Link to comment Share on other sites More sharing options...
BobP Posted November 21, 2010 Report Share Posted November 21, 2010 Spoonbender, Romanack also wrote the book "Precision Casting" which is where I got my data. Unfortunately, it didn't sell as well as "Precision Trolling" and has not been reissued since its publication in 2000. But it still contains data on lots of "classic" popular crankbaits from the large manufacturers and it's certainly worth a look-see for general info on crankbait depth performance. Quote Link to comment Share on other sites More sharing options...
RayburnGuy Posted November 21, 2010 Author Report Share Posted November 21, 2010 The title of the post may have been a little misleading as I was more interested in knowing if a side scan could be used to determine the depth of a crankbait. Never having used or even seen one I had no idea if it could be used in this manner. And now, thanks to Bob, I know it can't. thanks guys, Ben Quote Link to comment Share on other sites More sharing options...
spoonbender Posted November 22, 2010 Report Share Posted November 22, 2010 The title of the post may have been a little misleading as I was more interested in knowing if a side scan could be used to determine the depth of a crankbait. Never having used or even seen one I had no idea if it could be used in this manner. And now, thanks to Bob, I know it can't. thanks guys, Ben Sorry Ben.....my fingers were moving faster than my mind.....again.. Quote Link to comment Share on other sites More sharing options...
RayburnGuy Posted November 22, 2010 Author Report Share Posted November 22, 2010 Sorry Ben.....my fingers were moving faster than my mind.....again.. Nothing to be sorry for Spoonbender. As far as I'm concerned all information is good information and I appreciate the shared knowledge. I finally got a look at a side scan in action this weekend and it was awesome to say the least. I fell in love with it. Ben Quote Link to comment Share on other sites More sharing options...
hazmail Posted January 11, 2011 Report Share Posted January 11, 2011 They published a magazine here a few years back which was full of the stats for various lures both local and O/S- To get a fair comparison they were all trolled (in a dam) at the same speed and length of line past a vertical PVC pipe, this was calibrated and divers observing recorded each individual lure depth. From memory (which is bad) there were probably 500 different lures tested, I think there has been an updated version printed recently. It was called something like- "In depth lure fishing". Pete Quote Link to comment Share on other sites More sharing options...