What is the point of excluding water temperature? Is there water that has no temperature?

Hypothetically, why not just eliminate breathing and say the energy cost (of a dead body) is the same in any environment.

When people spew nonsense such as you did about survival in water, which is similar to the statement that 80% of your body heat loss is from the head, it just has to be called out and corrected.

But then, what else besides falsehoods/lies/BS can one expect from a Trumpeter?

I was brave. I tried. I read the post again. It is still hogwash.

Your exact words: "Excepting water temps, it’s definitely easy to survive days in open water. Once trained, it takes less energy to stay alive than sitting in a chair."

So let's put water temperature aside. Your premise is that a trained person will use less energy to stay alive if immersed in water vs sitting in a chair.

So I will ask you again:
How much energy does it take to stay alive sitting in a chair?
How much less energy does it take to stay alive immersed in water?
How much difference is there once you are trained?
How/why would training make a difference?

Now we have to bring in water temperature to make this practical:
How does water temperature influence the answers to the above questions?
Hint: at what water temperature would metabolic rate (energy utilization) be the same immersed vs sitting in a chair?
Where would you find "open water" at that temperature?
What are the effects of swimming/treading water on metabolic rate and rate of heat loss?

Let me know when you want me to throw you a life preserver.

I'm totally relaxed. You seem to be the one with your knickers in a knot... which apparently affects your brain.

"Energy to stay alive" is your way of saying metabolic rate to maintain a steady deep body temperature.

I am sure you would agree that your body loses more heat when immersed in cold water compared to when sitting in a chair. So metabolic rate to maintain a steady deep body temperature would be higher in cold water than when sitting on a chair.

So at what water temperature, when immersed, would your metabolic rate be the same as when sitting in a chair?

What is the effect of body movement (swimming, treading water, etc) on heat loss and metabolic rate?

Finally, explain why and how a "trained" person would respond differently than an untrained person?

Frankly, MoMo, I think you are "immersed over your head" on this one. You should simply get out before you drown.