What would make a good insulating material for a water bed?

[DD_BobK]

[nestork]

It is.

But, if you're laying on a water bed with nothing more than a blanket and the top wall of the water bed bag between you and the water, your body is going to lose heat through that minimal insulation to the water

15 times faster than if you were somehow suspended on air, or roughly 15 times as fast as if you were laying on a mattress.

If you were immersed in water, all of your skin would feel cold. On a water bed, you just feel like you're laying on something cold.

[mike]

Warm Woman??

Turns out that the body is extremely sensitive to the temperature of the water. Had a girlfriend for a while. We couldn't find a temperature for her waterbed that would allow us both to sleep comfortably. And there's just so much that you can do in bed when not sleeping.

Turned out to be a deal-breaker. Bummer!!

[Stormin Mormon]

Had a girlfriend for a while. We couldn't find a temperature for her waterbed that would allow us both to sleep comfortably. And there's just so much that you can do in bed when not sleeping.

Turned out to be a deal-breaker. Bummer!!

[nestork]

No, she needs to insulate to reduce the rate of heat loss from her body to the water.

Then, the bed won't feel cold to sleep on when she turns the temperature of the water down.

And, a lower water temperature will reduce the ambient air temperature in that bedroom, which is the problem the OP is trying to solve.

[Ed Pawlowski]

Usually both. In the winter, you don't necessarily want to heat the room from the waterbed so you keep a blanket and maybe heavy bedspread on it. Most people keep the water in the 85 to 90 degree range to feel warm.