dropshot worm performance?

[tubinator]

I did some tests of three different dropshot worms rigged on a lightwire hook in a 5 gallon bucket. Two of the worms manufactured by the "big boys" both would sit with their tails down, the worm I made stayed horizontal.

My question is, would this characteristic change in a real life situation? Say in 10-20-50 foot of water? And if so, how would it change?

[Gloomisman]

yes it would there would be more pressure on the worm. Probably make it float.

but I dont know that for sure I've never looked at a finessworm in 20fow.LOL

[MONKEYqpHUNTER]

lol me either

[nova]

Wouldn't the pressure be equal on all sides? If that is true it shouldn't have any effect on the worm. If it's going to float; it's going to float.

www.novalures.com

[Delw]

I did some tests of three different dropshot worms rigged on a lightwire hook in a 5 gallon bucket. Two of the worms manufactured by the "big boys" both would sit with their tails down, the worm I made stayed horizontal.

My question is, would this characteristic change in a real life situation? Say in 10-20-50 foot of water? And if so, how would it change?

The reason some major manufactures sink or sit with tails down is du to additives they put in there baits.

I assume yours was just pure plastic only this is why it will stay straight or float.

Wouldn't the pressure be equal on all sides? If that is true it shouldn't have any effect on the worm. If it's going to float; it's going to float.

www.novalures.com

Nova is right on the money

[tubinator]

Thanks for the input guys. I wasn't even thinking about water pressure, but more along the line of water density.

[nickcalderone]

Fresh water is: 0.43 psi per foot. So, for every 10 feet of depth, you will average 4.3 psi increase in pressure. The pressure is indeed equal on all sides.(interesting test: take a styrofoam head and tie a heavy weight to it with plenty of line. Drop it overboard in, say, 80 feet of water. Pull it back up, and let us know what your results are!) What I would think would affect the position of the worm would be it's specific density. This would correlate to the specific bouancy of the actual plastic including ANY additives. (thats what Del was talking about)

[Bassgrabber]

Also keep in mind that most of the big worm companies use a lot of salt in their baits. Salt will weigh it down.

[Smallie]

Fresh water is: 0.43 psi per foot. So, for every 10 feet of depth, you will average 4.3 psi increase in pressure. The pressure is indeed equal on all sides.(interesting test: take a styrofoam head and tie a heavy weight to it with plenty of line. Drop it overboard in, say, 80 feet of water. Pull it back up, and let us know what your results are!) What I would think would affect the position of the worm would be it's specific density. This would correlate to the specific bouancy of the actual plastic including ANY additives. (thats what Del was talking about)

This is somewhat true. The pressure is not exactly equal on all sides because the bottom is deeper than the top so on a bait, there is a slight upwards force. Unless this force is counteracted by weight in the bait (such as salt or a hook) the bait will rise.

[nickcalderone]

This is somewhat true. The pressure is not exactly equal on all sides because the bottom is deeper than the top so on a bait, there is a slight upwards force. Unless this force is counteracted by weight in the bait (such as salt or a hook) the bait will rise.

Um...not to be "particular", but what do you mean by "the bottom is deeper than the top"? Pressure is relative to depth. The specific bouancy of an object is determined by it's composition. That is why rocks sink. They are more dense than the water itself. Foam floats because it is less dense than water. Plastisol has a somewhat neutral bouancy depending on what additives are in it. Plastisol by itself will simply float. Add a specified amount of salt for example( or other additive) equal to or greater than the density of water, and it will sink. It has nothing to do with the "bottom being deeper than the top". That is why I suggested the experiement in my previous post...to prove that pressure is indeed equal. If you were to try that experiement, you will see that when you pull the foam head from the water, it will have shrunk uniformly! Of course, you would have to sink it to a specified depth greater than the overall density of the foam itself. And the deeper you submerse it, the more it would compress...within the limits of the compound (foam) of course. To throw another curve in here, saltwater is slightly more dense because of the salinity content. That is why you are slightly more bouyant in salt water. Maybe that is why saltwater fish seem easier to catch...all that pressure makes them dense! (hahaha)Density...pressure...sounds like a day at work!

[Smallie]

What I was trying to describe was the buoyant force that acts on the bait. It is not equal all around the bait. The force is greater on the bottom of the bait than on the top. As long as the density of the bait is less than the density of the water, the greater force on the bottom will cause the bait to rise. If this wasn't true, there would be a depth at which a bait that would float on the surface would suspend.

Density of salt water is greater than fresh so a bait will behave differently in salt water than it did in fresh. Look at the great salt lake. It is so salty, people float effortlessly on the surface.

[Vodkaman]

Smallie, I'm not really getting your point with the distribution of the buoyancy forces, having more force on the bottom.

[Smallie]

Archimedes principle is the law of buoyancy. It states that "any body partially or completely submerged in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the body."

The weight of an object acts downward, and the buoyant force provided by the displaced fluid acts upward, thus the force pushing on the bottom of the bait is greater than that on the sides or top.

If these downward force from the bait and the upward force from the water are equal, the object floats.

The initial premise was the forces acting on a bait are equal 360 degrees around when it is submerged. That is violates Archimedes principle. The bait stays submerged because its density is greater than the density of the water, not because the forces are equal around the perimeter.

Salt water is denser than fresh so a bait that suspends (is in equilibrium) in fresh water will rise in salt water. If you have ever played with weighting jerkbaits so they suspend, you may have seen a bait that suspended perfectly at ice out will rise when you throw it to post spawn bass because the water is warmer and its density has changed.

[Senkosam]

Let me give this a try (with a little help from my old text book). (It’s been decades since I studied chemistry.)

Buoyancy is caused by a difference in fluid pressure at different levels in the fluid. Particles at the lower levels are pushed down by the weight of all the particles above them; the particles at the upper levels have less weight above them. Consequently, there is always greater pressure below an object than above it, so the fluid constantly pushes the object upward. (IE a hot air balloon rising into the atmosphere against the pull of gravity)

The force of buoyancy on an object is equal to the weight of the fluid displaced by that object. An object with greater volume is pushed upward with greater force because it displaces more fluid. If the object is denser (and therefore heavier) than water (or air in the atmosphere, it doesn't matter how much water it displaces -- it will still sink. (IE a sinking Titanic versus one that floated)

To put it simply, an object will float depending on how much it weighs (mass) versus how much space it takes up (volume).

The forces of buoyancy and gravity cancel each other out when a large enough volume compensates for an objects density. For example, to stay at a particular level, a fish fills its bladder to the point at which it displaces a volume of water that weighs what the fish weighs, causing upward and downward forces to be equalized.

A finesse worm floats because its volume compensates for its density and the depth at which it suspends is based on that balance. Suspending jerk baits, hard or soft, take that balance into consideration. To get a salted bait to suspend or float, requires a larger bait volume, which makes me wonder why anyone would suggest using Senkos C-rigged rather than a bait that is more buoyant; ditto for Zoom's heavy topwater buzz frogs.

Question:

Will an X-rap float upwards if in 60’ of water versus at 15’?

BTW, I question whether water temp has much to do with an object's buoyancy.

Also, as to the statement, "the pressure is not exactly equal on all sides because the bottom is deeper than the top so on a bait, there is a slight upwards force", the position of a bait's bottom relative to its top has little to do with its buoyancy. A bait could be upside-down and yet relative buoyancy would still be determined by the volume (displacement) / density relationship.

[Smallie]

I Googled Archimedes principle and found the following. I italicized the sentance that says what I was trying to describe with my top versus bottom comment.

If a cubic centimeter of aluminum was suspended in a fluid such as water with a very thin and negligible thread, the metal cube would have the fluid exerting pressure on the cube. Try to imagine that if the cube were to disappear, and the fluid would magically replace the cube, then the surrounding water would support this cube that is now containing water, so that the cube of water would be motionless. That is, the forces would be balanced. The cube of water would push out on the surrounding water and the surrounding water would push back on the cube. The fluid would be static, or stationary. Now replace this same cube of water with the original cube of aluminum. The surrounding water would not 'know' that the cube has been replaced with another substance. It would still push inward and upward and downward with the same force that it pushed on the cube of water. The sideways forces would be balanced and oppose each other equally, but the upward and downward forces would not be the same. The pressure at the bottom of the cube is greater than the pressure at the top of the cube, because pressure increases with increased depth. The difference between the upward and downward forces acting on the bottom and the top of the cube, respectively,is called buoyancy.

[End Quote]

Located at:

Bouyancy: Archimedes Principle

[Vodkaman]

Ahh, now I get it. Thankyou.

[nova]

Thank goodness for old dead Greek guys; lol.

www.novalures.com

[reelnmn]

Not trying to beat a dead horse...but here's the way I'm seeing it:

Quote from Smallie:

The pressure at the bottom of the cube is greater than the pressure at the top of the cube, because pressure increases with increased depth. The difference between the upward and downward forces acting on the bottom and the top of the cube, respectively,is called buoyancy.

The keyword is difference. Yes the pressure does increases by approximately .43psi per foot. However, because the increase in pressure is constant, the "difference between the upward and downward forces acting on the bottom and top of the cube[bait]" is constant...therefore the bouyancy is constant - regardless of depth. So a bait that suspends at 1' should suspend at 100' as long as the temperature is equal - which it never will be.

[Senkosam]

I see what you were trying to say, namely, the lowest part or surface of an object suspended in a fluid (and therefore the furthest from the atmosphere), has a greater pressure exerted on that surface than the surface closest to the atmosphere.

Having read the thread and done a little research, all the information clarifies to me why battleships float and Senkos don't! But one thing that is so important in lure design that supersedes buoyancy, are hydrodynamics. None of us have to understant the concepts to design a unique lure, but understanding how different lure parts or components dictate why a design is unique, is of utmost importance.

I was out yesterday trying different hybrid soft plastics in my pond that my neighbor and I came up with in the winter months. A few baits I thought would do well, didn't; those that I was certain wouldn't have nice action, did. Even the cheap 4" Sassy Shad k/o shown in a previous thread, had IMO as good a shimmy as any of the Bastrix hollow minnow baits going for 200% more. I took photos of the lot this morning and will refer back to them for reproduction.

Viewed in the semiclear water with polarized glasses, it was obvious why certain baits worked and at the same time blew away some misconceptions I had of design. The most important thing I was trying for in most lures was how slow I could move them to get action. Those that I had to move very fast to get component or body action, failed the test. Some poured and manufactured k/os, as well as a few Senkos that I thought would have a nice, wacky worm shimmy, didn't. Some Mann lizards were crap!

If a soft plastic bait doesn't work in the water in a desired retrieve(s), it doesn't matter how nice the lure looks or feels. Iceout give me the opportunity to test many baits before I do some serious fishing. (BTW, a yellow perch came out from under the ice into the 10' width of open water and tried to take one of the new baits.)

[nova]

Frank; I believe that you are refering to hyrodynamics. The action resulting from the resistance of the water against the the retrieval forces of the bait.

Basically; that is what I'm most concerned about when I design a bait.

www.novalures.com

[Senkosam]

Frank; I believe that you are refering to hyrodynamics. The action resulting from the resistance of the water against the the retrieval forces of the bait.

But one thing that is so important in lure design that supersedes buoyancy, are hydrodynamics.

I couldn't find the term hyrodynamics, only hydrostatics.

hy·dro·dy·nam·ics

: a branch of physics that deals with the motion of fluids and the forces acting on solid bodies immersed in fluids and in motion relative to them.

The principles of lift, pitch and yaw, etc. found in aerodynamics applies to most hydrodynamics principles. I wonder how many new lure designs were done on a computer loaded with hydrodynamics formulas and then sent to a lazer program to cut the mold.

[nova]

I'm sure that is done all the time. First with a 3-D program and then with the hydro programs.

After all; the bait has to work before they can make it pretty,lol.

www.novalures.com

[Vodkaman]

I have thought long and hard about the application of CFD (computerised fluid dynamics) software. It is possible that one or two of the big boys are using it, but I am not convinced of its usefulness.

What I have realized is that the lure is constantly moving and in doing so, all the angles etc are constantly changing. An easy job for CFD's would be to place a complex static model of an object in the flow and predict the flow patterns and pressures etc. If the model was continually moving and the CFD program had to predict the movement also, the computations would be massive.

Maybe it is possible, but the user skill required to get it to work would probably be beyond us mortals. Very expensive software too (software called "fluent").

I have found that it is enough to understand how the lure theory works. This gives you enough knowledge to seek out undiscovered features and promotes innovation.

As for the original question, the plastic worm contains no air (or very little) and is therefore not going to deform like the expanded polystyrene experiment. In fact, I suspect that, like water, the compressibility of the plastic will be very low. As the worm is not changing shape etc, my groveling opinion is that it will behave at depth, the same as just below the surface.

There must be a few members that do scuba. We’ll have to set up a load of depth experiments for someone to go get the answers!

[Spike-A-Pike]

There must be a few members that do scuba. We’ll have to set up a load of depth experiments for someone to go get the answers!

Yes, we could see if a member, who is a certified diver, would be willing to preform depth testing experiments; then someone (and you know I would) would argue that you didn't go to a depth deep enough to determine a conclusive result.

Therefore, we need to determine the feasibility of sending a small submarine into the Marianas Trench to Challenger Deep, the deepest part of the trench and see if the plastic worm's surface deflection can be measured at the bottom of the water column which exerts a pressure of 108.6 MPa, or over one thousand times the standard atmospheric pressure at sea level.

Or we could just skip it... what ever you guys want to do is okay by me.

[Smallie]

For those of us that don't think metric the 108.6 MPa is almost 16000 PSI.