For all you fishermen that are also well versed in science:

if you are fishing a C-Rig with a 10 inch worm on it in 2 foot of water the worm/hook combo will sit on the bottom of the lake, if you fish it in 25ft of water will the worm/hook combo become more buoyant and float up off the lake bottom ?
in other words, the deeper in the water one puts an object does it become more buoyant ?

does anyone know if a standard fluke with a 4 ought hook will float off the bottom at 15-20-25 foot deep ?

I have had experience with this in the past with SCUBA.
The deeper you go in the water the greater the pressure on the submerged item, therefore it becomes denser as compared to its size. Thus in your example it should be less buoyant.

My instinctive answer would be less buoyant also. As a fish dives deeper, it's air bladder inflates to assist with needed additional buoyancy.

As you dive deeper, the water pressure increases. This increased pressure decreases the volume of air and liquid in your body, making you less buoyant.

If we extrapolate this to a plastic fishing lure. As the lure increases it's depth, the volume of air in the lure will decrease and more air will be squeezed out of it, making it less buoyant.

The only baits that float on a c-rig, regardless of depth, are those baits with air chambers or plastics made to float such as the old Fliptail floating lizard. Otherwise, you're simply dragging bottom. Albeit with a heavier weight which causes disturbance and attracts the fish. Along comes your plastic and wham! If you want your bait to hover above bottom, fish a drop shot.

The more submerged an object is, the more affected it is by buoyancy. The deeper you fish it in the water, the "lighter" it becomes.

But, water is pretty much incompressible. It's density does not change much as you fish deeper. The density may vary a bit with temperature, but that isn't going to be much either.

What may change a bit is the displaced volume. If the plastic had air in it's structure, it will be compressed, and the displaced volume will go down.

So the answer is that the bait is a bit less buoyant because the volume of water displaced is going to go down because of the increase in pressure.

With turbulence generated from the lure moving along the bottom (thrust), through water, some of the water turbulence could create some lift force on the lure, resulting in some transitory lifting off the bottom.

Less

It will sink, the deeper you go the denser and more compressed the object will be like Traveling East said. The more dense and compact the object the less surface area it will have so like collincountytx said there will be a little bit of "upward" thrust but the bait will have less surface area to be affected by the thrust. Long story short, its gonna sink!

Very good points and very sound reasoning.
Now my next question ..... and I only ask this because I do not know and would like to:
If it (anything)gets LESS buoyant as it gets deeper, why does it take a heavier weight to get a T-Rig to 24ft than it does at 6ft or should I say why do you use a heavier weight for deeper depths ? waves & wind not being an issue .....

is it a "get you to the bottom" quicker thing

Yes, that and for better feel. The deeper you go, the harder it is to feel what's going on with your bait. Hence the heavier weights for a TX rig.

If anyone wants a c rig plastic that REALLY floats even down deep, get some Z Man Elaztech plastics. The turbo craw will float a 3/0 EWG at least 20' down. And that's one of the smaller profile plastics they have.

This set up will sink at any depth that you would bass fish

Basically because of the line resistance through all that water giving the C-Rig lift off the bottom. I still use a light weight just put out more line thus, long lining comes into play with my C-Rig and Deep Water Spinner Baits. The lighter the weight the more line you have to give to keep it down there because of water resistance.

I am always moving with my C-Rig; called dragging. The water resistance really comes into play if you are moving, so therefore it is more difficult to keep down there and in contact with the bottom. Most fisherman want this heavy weight to accomplish several things.
- Easier to keep on the bottom
- Bottom disturbance to attract the bass
- Keep slack out of the line when the wind is blowing

I use a light weight because I know it hangs up on the structure less often, thus less break offs. I like a subtle approach with no noise, beads or clickers. I also feel that it catches more fish in the mid-rang depths through heavy cover.

I've started using the Betts Carolina floaters on my c/rig. Looks like a bullet weight. Looking at it work in shallow water, it does lift the worm a little. I'm going to experiment with and without it and see if it makes any difference