Crankbaits and bottom bouncers

[BobT]

In a discussion today about using lures a thought came up and I’d like to hear other opinions.

Suppose you have a floating shad rap that dives to about 10 feet. We were talking about using one on a heavy bottom bouncer to get it down to 20 feet deep. At that point assuming the bottom bouncer would stay on the bottom I asked, “Wouldn’t that force the shad rap to dive into the dirt on the bottom of the lake?” The reply I got was, “No because due to the buoyancy of the shad rap it won’t be able to dive but would actually hover somewhere above the depth of the bottom bouncer. You can control how far it rises above bottom by the length of the leader from the bottom bouncer to the crankbait.”

I never thought about this before. Are they right about that? Interesting idea.

[gurkster]

I have never tried this idea, but I think they are correct.

[Wanderer]

Dead wrong. The bait will continue to dive deeper than the bottom bouncer. It would be physically impossible for the lure to swim with any action higher than the bouncer. The depth the lure would dive further than the bouncer would be determined by the leader length though.

[Lund79]

Wouldn't it be the same as if you were using 3 way rig?

[TooTallTom]

I don't know.

I've always figured that the depth to which a crank will dive is a factor of the size of the lip and the bouyancy (sp?) of the material from which the crank is made.

Bouyancy depends on the amount of water pressure acting on the crank. A given material will naturally "float" at a given depth if you leave it alone.

So, if a crank will naturally float on the surface, but has a lip that will take it to 10', I think that the bouyancy of the lure will have a greater effect on behavior than the lip.

Basically, I think that the lure will not dive any more, but will seek to return to some shallower depth. I think it will float.

Obviously, this is all speculation on my part...

[BobT]

That was pretty much their theory Tom. The deeper the lure is submerged the stronger the bouyancy will tend to "push" it toward the surface. The lip of the lure can only pull it down so far before the bouyancy of the lure overpowers it. It does make some sense but I wonder too if the line would begin to interfere with the action of the lure. Anyone use diving cranks on bottom bouncers or heavy sinkers? Do they tend to dive into the bottom or stay some distance above?

[Wanderer]

We are speaking of lure designed to dive 10 feet on an average cast or trolled to with a certain amount of line out. The lip needs to overcome the bouancy to dive and swim. You will have to pull it fast enough to get the correct action from the lure. So, I suppose if someone wanted to argue that if you go slow enough the lure could run higher but the action wouldn't be as designed either.

I don't run cranks with bottom bouncers but have run them behind dipsies and down riggers. When the bait bounces bottom it's my cue to raise the dipsie or the rigger ball before either of them hit.

An original Rapala behind these rigs should run at close to the same level though since those lips are small and disigned more for action than diving.

I know there are guys who troll alot more than I do that will be weighing in and it'll be interesting to see more responses. I would be as shocked as Jesse Ventura if I'm wrong.

[hanson]

Wanderer... you are not wrong.

Lot of guys pull Shad Raps, Flicker Shads, Hornets, etc on Leadcore in 20-30' of water.

If you have a 20' leader of mono, you are supposed to factor in the diving depth of that lure

at 20', then add 5' of depth for every color (10 yards) of leadcore. In 30' of water, that

lure is still diving its natural dive curve behind the leadcore.

If I were to use a bottom bouncer pulling cranks, I could use a 3 way as well, it would be the same situation for me. With the 3 way, you can adjust the depth of your dropper weight to get you off the bottom further. Most guys are running original floating raps on their 3 ways, about 6' or so behind the weight. A floater won't dive much at all on 6' of line, and it will only rise up if paused.

[yaggie]

This past weekend I had to run my down riggers down 16 feet to get my #7 rap to run at 23 feet. Bottom bouncer would be the same but its hard to tell how far down your bouncer is running but your lure will dive to the designed depth below your bouncer.

[solbes]

Here's my interpretation of how a crankbait dives. It's a balance of:

1) Downward force produced from the lip (affected by angle of line out)

2) Upward force or drag produced from the line itself (why line diameter is so critical to ultimate depth)

3) Natural boyouncy of the crankbait (can be floater, suspending, or sinking)

It's my guess that #1 and #2 are the dominating factors at play here. #3 has to have an effect, but I would guess its importance has more to do with speed (i.e. if you are traveling fast enough it does not have much effect to the balance equation). Sure the water pressure may have an effect on #3, but again I think it's almost neglible at trolling speed.

The dive of the lure should be independent of whether a BB is used or not. Yes the BB will start the dive curve deeper, but the crankbait should then follow the same line out vs depth curve that applies without a BB.

And the lure should never rise above the BB, unless it's a floater and you are traveling under a minimum speed.

[harvey lee]

Wanderer... you are not wrong.

Lot of guys pull Shad Raps, Flicker Shads, Hornets, etc on Leadcore in 20-30' of water.

If you have a 20' leader of mono, you are supposed to factor in the diving depth of that lure

at 20', then add 5' of depth for every color (10 yards) of leadcore. In 30' of water, that

lure is still diving its natural dive curve behind the leadcore.

If I were to use a bottom bouncer pulling cranks, I could use a 3 way as well, it would be the same situation for me. With the 3 way, you can adjust the depth of your dropper weight to get you off the bottom further. Most guys are running original floating raps on their 3 ways, about 6' or so behind the weight. A floater won't dive much at all on 6' of line, and it will only rise up if paused.

I agree 100% Chris.

[TooTallTom]

Wiser minds than mine... Thanks for the information folks!

[hanson]

Wiser minds than mine... Thanks for the information folks!

To add a bit more meat to the conversation here... buoyancy IS important though!

Lets just use crankbait trolling for walleyes as an example. Fall is coming up where we have a shallow water night trolling pattern going on. Crankbaits like a Rapala Husky Jerk and Smithwick Super Rogue are neutrally buoyant. When trolled, you can park the boat in neutral and let the baits sit there, and then take off again. This is a great triggering move. In snaggy, rockier bottoms, a balsa bait is great cause you can stop the boat or let out line and the bait will "back out" when snagged up. Not to mention this can be a great trigger as well.

So a buoyant bait will dive when moving, regardless of how it gets to its depth (leadcore, snap weights, bottom bouncer) but when the forward motion is stopped, it may react in a way that triggers a fish to bite.

[Basschaser]

Yes, the dive of the crankbait is independent of the bottom bouncer. Since water can be considered in this case to be an incompressible fluid, the buoyancy force on the lure is the same regardless if it's 1 foot deep or 30 feet deep. Fishing a crankbait with a bottom bouncer would be like fishing a DT16 in 15 feet of water.

[fivebucks]

the buoyancy force on the lure is the same regardless if it's 1 foot deep or 30 feet deep.

This may not be true, not sure. The pressure at 30 feet is much greater than at 1 foot but I don't know if that effects buoyancy. If you scuba dive deeper than 30 feet you have to rise at a certain slow rate to avoid the bends. Just throwing more stuff into the mix. I would think a lure runs the same depth whether trolled from the surface or from 20 feet down but...

[BobT]

Yes, the dive of the crankbait is independent of the bottom bouncer. Since water can be considered in this case to be an incompressible fluid, the buoyancy force on the lure is the same regardless if it's 1 foot deep or 30 feet deep. Fishing a crankbait with a bottom bouncer would be like fishing a DT16 in 15 feet of water.

I don't agree. Try to dive wearing a PFD and see how far you can get. I will guarantee the deeper you try to go the harder it will be. This is why I was supporting the idea that the crankbait will not dive the same distance below the level of the weight holding it down. The bouyancy of the lure will become more and more evident the deeper you go because the density of the water is getting higher. In other words, suppose you put a crankbait 20 feet behind a sinker and hold the sinker at the water's surface and it dives 5 feet. Now lower the sinker to a depth of 20 feet and it would not surprise me to learn that the crankbait will not dive to 25 feet because it won't be able to overcome the added resistance from the water.

This is also evident when using jigs. Why do we use heavier jigs in deeper water? Because deeper water is more dense and the lighter jigs won’t sink that far, especially when they are dragging some line with them.

[TruthWalleyes]

It's like diving into deep water and your ears feel like they are going to explode. So yes, i would agree that the deeper you go the more boyant a lure can become, however i an not sure of the magnitude of the boyancy change...that could be tested.

I will disagree with the jig comment however, since there is no boyancy in lead, or rather it is more dense that the water. But the line resistance is greater the more line you let out, and it is the weight of the jig that compensates for the resistance on the line that keeps your jig vertical as your boat is moving, or water is moving.

[SkunkedAgain]

....but to BobT's point, how come you need a 1/4oz jig versus an 1/8oz jig to get to deeper depths when vertically fishing?

[solbes]

An 1/8 jig would dive to an unlimited depth if it wasn't for line resistance/line bouyancy. It will always be denser than water, at least in the realm of fresh water fishing.

You just have much better feel for the heavier jig in deep water. And the line resistance has more effect at these depths, thus heavier jigs to counteract this.

I still maintain bouyancy of a crankbait has little effect on depth reached if you are trolling at a minimum speed.

[TooTallTom]

You don't need it to get to deeper depths, you need it to get there quickly and also to continue to provide feedback with increased line stretch.

One possible experiment to help resolve the bouyancy question would be to hang sinkers of various weights from a crank and see how far below the surface it gets pulled. If all weights pull the crank to the same depth, bouyancy does not change with increased depth.

[BobT]

I propose that the deeper you go the more dense the water due to gravity and as the water density increses, the heavier an object it can support. In other words, eventually even a lead jig will suspend or float when the amount of water it displaces is equal to the weight of the jig.

In a similar way, the lip of the crankbait can only apply X force downward and eventually that will not be adequate to overcome the force created by the bouyancy of the lure. Of course there is a counter-argument I think. As you go deeper the water becomes more dense so does it also have a stronger impact on the force created by the lip of the lure?

Obviously, the best way to answer this question is to go out on the water with a downrigger and a crankbait and test things at different depths to see if there's a depth at which the crankbait no longer dives below the downrigger. The only problem is would there be an ability to "feel" or otherwise sense when the crankbait is actually digging into the bottom of the lake? Maybe a diver would be necessary.

I think we need a physicist to chime in with some raw math for us.

[Wanderer]

The only problem is would there be an ability to "feel" or otherwise sense when the crankbait is actually digging into the bottom of the lake? Maybe a diver would be necessary.

I think we need a physicist to chime in with some raw math for us.

I doesn't take a physicist to know if your crank bait is digging bottom behind weight - even a downrigger ball. It just takes an observationist.

[BobT]

I finally have the answer! I didn't realize this when I started this thread but I have beome enlightened. The real unconscious reason I started this discussion was because WE ALL NEED TO GET OUT ON THE WATER AND TEST OUR THEORIES! That means getting into a boat and wetting some lines and who cares if we answer this riddle so long as we enjoy trying and if we catch a fish in the process, Yee-Haw!

[eagle_3464]

I think the design of the crank will have a huge impact on the results. My guess is that a diving type crank will continue to dive regardless of what depth you run the BB. On the other hand, if you are running a floating shallow runner there may be a certain depth where the natural bouyancy will overcome the lips design. Regardless, either senario will not work with the OP situation. If the BB is run on the bottom a diving type crank will dig the bottom. If the natural bouyancy takes over, the crank will not run properly. In nearly all cranks, the line eye is above the lip so if you want to argue that the crank will suspend above the BB, it will have to do so on its side or upside down. This is why, if you want to run cranks deeper than designed, you run them on lead core, downrigger, or dipsey.

[hanson]

I don't care how deep the water is or how light the object is, things sink to the bottom.

Even in the ocean with thousands of feet of depth, stuff sinks to the bottom.