338muskie

bouyancy change

20 posts in this topic

I read this on Muskiefrist got any commet's. I was going to down to test a lure in the river. Is this true?

One thing to remember is bouyancy changes with water temp. What floats in 36 degree water temp may sink like a rock at 70. you may screw up alot of baits with drilling and pourng lead, but heck, neccesity is the mother of invention.

Thanks

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it's very possible, keep in mind, hot air go's up. But i think that the changes are very insignificant,

This IS a good question for Vodkaman:teef:

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The density of anything changes with temperature. Something in a solid state (like your lure) is affected much less (most of the time the change is negligible) than a liquid or a gas. So, yes...that is true. Especially if you are trying to get a bait to suspend. Water at 36 degrees is more dense than 70 degrees, but the density of your lure won't change enough to be noticeable.

look at the density of water and ice section...

http://en.wikipedia.org/wiki/Water_(molecule)

Eric

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Yes,

It makes a difference. Water is more dense as it gets colder. Buoyancy is a comparison of the weight of an object compared to the weight of the volume of water it displaces. Since the volume remains the same, but the weight of the water is greater at cooler temperature, the object (lure) is more buoyant at colder water temps.

That said, it's probally not a huge deal unless you are trying to suspend a bait, or have it fall/rise at a certain rate.

For that mater, at depth, the increase in pressure along with the cooler water temps should have a muting effect on lure action as it dives/is trolled behind a downrigger ball...

Clemmy

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As a Jewish carpenter, I have a confession to make.

I can only walk on water that's below 32 degrees. :o)

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OK... heck.. Me and JT got into this discussion a few months back!!! JT helped me out.. I dont like to step on toes.. Heck normally Im only here to have fun. But I think you guys got it backwards.. Heck I always thought if the water was colder it was more bouyant too.. Dont ask me why... VOKDAMAN!!! but I believe a lure that sinks in water temps below 58 degrees could float at 70, 80 or even 90!!! All I can tell you is I have put some in a test tank at 40, 50, 60 degrees and they sink.. then at 75 degrees and they Float... I believe water is more bouyant at higher temps!! not at lower ones! I know that sounds crazy!!! but hell I could be wrong.. I have been wrong before. But I think Im right!! I think it's something to do with the tempature of the air trapped inside the plastic lure.. If that is not the case it sounds good and I did sleep at a Holiday INN last night!!! I dont know about wood.. I have never tested it at really low temps!! Heck its hard to sink!! I use balsa!! and cedar!!.. I really dont know much about science. I was busy trying to get Julie Johnson to go out with me during that class!! BOY!! Im glad she didnt.. I saw her last May!! Garth your right!! UNANSWERED PRAYS!!!.. Come to think of it!! WHY AM I EVEN POSTING ON THIS SUBJECT!!! where is my skoal!!! HELP ME DAVE!! HELP ME!!!

The Rookie

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The Rookie

Your bait must be shrinking in the cold water, changing its volume and there fore changing its buoyancy or the pours on the bait or opening up allowing water to come in. This will change the weight of the bait. You could check this by measuring and weighting the bait when it is hot and cold.

Whiz Jig

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I have been away from this post, to do a little research on the subject. What I thought was fairly straight forward, turns out to be far more complicated. As we just want to make a bait suspend on a cold day, I see no advantage in getting heavy on the subject.

There is nothing wrong that has been discussed on this thread so far, apart from Rookie changing his mind half way through.

The buoyancy of the lure depends on the density of the water AND the average density of the lure.

Consider the water.

The density is affected by temperature, depth and salinity.

Temperature. As temperature increases, molecules move faster and the water becomes lighter or less dense and the buoyancy of the lure relative to the water, decreases (it sinks). As temperature decreases, molecules slow down, water becomes thicker, the density increases. The buoyancy of the lure relative to the water increases (it floats).

Salinity. Everyone knows, that if you swim in the dead sea (very salty), it is easy to float, so no need for further discussion. Accept, if you set your lure in tap water, to suspend. Regardless of temperature, don't expect it to behave the same at the lake, as the salinity will not be the same. Even fresh water has salts in it.

Depth. I found lots of information on temperature and salinity, but very little on depth. But the pressure of depth would compress the molecules and have the same effect as cooling and the density would increase, thus the buoyancy of the lure would increase.

Summary. The deeper the lure swims, the cooler the water gets, the saltier the water gets, the more the lure wants to float. BUT, this is only half the story.

Consider the lure.

This is where things start to get more complicated. At one end of the scale, we have hard shelled bodies. These include hollow plastic bodies, 16lb foam bodies and resin/micro-balloon bodies. These bodies can be considered incompressible. So the average density of these lures remains constant. This means that only the water properties need to be considered i.e. lower temperature and more salt means more buoyancy or float.

At the other end of the scale, are soft bodies. These include hollow soft shelled bodies and balsa bodies. These bodies are compressible. As the body is compressed, its average density increases. So the deeper the lure swims, the more pressure the body feels and the body is compressed or squeezed and its density increases. As the density increases, its buoyancy decreases and the lure will want to sink.

A good example of this is the human body. Snorkeling is accepted to be safe down to a depth of 32ft. The reason for this is that the body, with a lung full of air, will tend to float upwards. But at depths greater than 32ft, the pressure of the water on the lungs, compresses the air. This reduces the average density of our body. The result is that after 32ft, the body sinks and you have to fight your way back to the surface.

In addition, the air inside the lure changes volume, due to temperature. This shrinking of the air as the temperature drops, also causes the average density of the lure to increase and reduces the buoyancy of the lure.

It would be possible to have a soft bodied lure, tuned to suspend just below the surface, but as the lure dives deep, it loses its buoyancy and would sink further, rather than trying to return to the suspension depth.

Even the shape of the body is significant. A deep, flat sided body would be more susceptible to compression than a ‘cigar’ shaped body.

Summary. The deeper the lure swims, the more the lure wants to sink.

So the effect of water and the effect of compressed air in the body, contradict each other. This could explain some of the anomalies posted on this subject in the past. The big question is which effect is stronger. I was unable to find any tables of depth/density figures. My guess, is that compressible bodies would feel the most effect. Density changes in the water due to depth would have the least effect. But the really important considerations would be temperature and salinity.

Hardly BS, but what do we gain from the above information? Certainly no practical help. It explains that a bait rigged as a suspender will only suspend at the required depth on one lake and as long as the temperature does not change. But so what. The purpose of tuning a bait to suspend, is to get some hang time, so when you stop the retrieve, it does not sink like a stone or pop to the surface like a cork. If it slowly rises or falls, the aim is achieved.

Something else to consider, are temperature variations through the depth of a lake. The temperature from top to bottom is not a gradual change, but a fairly sudden change. This sudden change of temperature is called the thermocline. There are a bunch of other “clines” to read about too! The floating, warmer water above the thermocline gets blown about the lake on a windy day. So, temperature of the water at the lake side with the big waves, will be warmer. It is also conceivable that the fish would hang around the thermocline, or just above it, for favorable conditions (I read this somewhere a long time ago).

A lot of what I have discussed in this post, has already been discussed by others in this thread, but it took so long to write this, I wasn’t going to edit it down again, so apologies for any duplication. I’m sure I have probably made a mistake or two above and said sink when I should have said swim. At least it will give the technophobes something to pick holes in. It beats reading another Devcon sales pitch and I did learn a few things on the journey.

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I have a new STANDARD POST!!! Im just going to copy and paste!!!

"Ask V-man!!!" Your amazing Dave!! I dont know how you find the time!! We all should pay you for this info!! Do you want a truck lure? I willing to part with one!!

The Rookie

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Rookie, if you check this out, you'll find out that its true...

They hydrodynamics of an apostokaietetic material are inversely proportional to the temperature difference (measured in kelms, not Fahrenheit or celsius). As the kelms increase, the body of the bait takes on carenic variations, which cause the kelms to fire bursts of anti-gravity. The anti-gravity effects, which manifest themselves as what is commonly called "buoyancy," are the cause of the ergoseptic failure, causing the subsidy of the kelms. The result? The bait sinks.:yeah::lol:

What does this mean to you? It means that you should build SUVs for your higher end bass. These higher end bass can afford a better meal.:lol::lol::lol::yay:

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Mikey said he lives in Kannapolis and the bass on his side of the town are flat broke!! So he is stickin to Sanford and Son Type trucks!!!

I wish yall could have heard Mikey tell me about the first fish he ever caught after we were driving home from a day of testing on the Lake Tuesday!!!! It started out like this:

" So I started looking then I said...Hey MOMMA you got a paper clip!!!"

The Rookie

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Mikey said he lives in Kannapolis and the bass on his side of the town are flat broke!! So he is stickin to Sanford and Son Type trucks!!!

I wish yall could have heard Mikey tell me about the first fish he ever caught after we were driving home from a day of testing on the Lake Tuesday!!!! It started out like this:

" So I started looking then I said...Hey MOMMA you got a paper clip!!!"

The Rookie

Rook, I really think that the guys at Bassmaster used you and Mikey as prototypes for their Harry N Charlie characters. :D

You sure ya ain't from E. KY?

Later

David

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Vman, also want to add my thanks for all your research on this subject and paring it down so even a dummy like me can understand. I admire all you intellectuals that can research this stuff. Keep up all your good work.

David

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