DF,
Man your discovery has really piqued my curiosity.
Okay, so it isn't the line. I use 10# Pline CX Premium myself.!? I can't remember at what # test diameter (going thinner) that a crankbait's ability to dive deeper is also inhibited. I think (and I'm guessing) that it is around the 6-8 mono equivalent diameter that the thinner line no longer has the benefit of enabling the crank bait dive deeper. 10# Pline should be thinner that 10# mono.
Also, what about the reels used? If one reel had a higher line recovery rate than the other and you made the same retrieve with both reels, then in theory, the reel with the higher line recovery should not allow the crank bait to get as deep. Why? I would speculate because it is sucking up the line much more quickly and it is that same line the crankbait needs to get to its depth.
Take a look at the line recovery rates for both reels. This should be the key. Gear ratios between reel manufacturers might be the same or similar but that does not necessarily mean that the reels would have the same line recovery rate.
For example, a Superfree Curado with a 6.2:1 gear ratio has a line recovery rate (LRR) of 23" and an Abu Garcia C4 with a 6.3:1 ratio has an LRR of 25". A Shimano 301A Cardiff at 5.8:1 recovers line at 24" and a Shimano Symetre spinning reel at 6.1:1 recovers 31" of line.
If the reels have a different line recovery rate and the rig with the greater line recovery is the one that didn't allow the crankbait to dive as deep as you hoped, then we will have solved the mystery. If they have the same line recovery rate or the rig with the lesser line recovery is the one that didn't get the crank bait deeper, it will be a problem whose solution is beyond my extremely limited math and fishing knowledge.
Let me know what you find and thanks!
-ib
