Can putting items with high heat capacity smooth out heat changes in Sous Vide?

Question

So was recently thinking about the beer cooler sous vide method and had a thought:

While heating the water to put in the beer cooler, if you were to place an object with a high heat capacity (e.g. a ceramic coffee cup) in the water, heat both to the desired temperature and then place them in the beer cooler, would that help keep the water at a more constant temperature?

In other words, since you are replacing some of the water with a material at a higher heat capacity at the same temperature that would in turn keep the rest of the water warmer for a longer period, correct?

Answer 1

Water has one of the highest heat capacities available:

http://en.wikipedia.org/wiki/Heat_capacity#Table_of_specific_heat_capacities

Your ceramic is not going to hold nearly as much heat as the water bath itself.

If you are finding that your bath is cooling too quickly then you are better off investigating your cooler.

Answer 2

Water itself has the highest volumetric heat capacity of most readily available materials: Table of specific heat capacities.

Adding rocks, ceramic coffee cups or lumps of iron to your beer cooler will just displace water, and lower the total heat content.

Answer 3

While it's true that Water has one of the highest volumetric heat capacity of any material, stones can store more heat overall.

One of the main reasons for using stones / etc for storing heat is that water is limited to 212F while stone or other solids can be heated to a much higher temperature and retain heat.

For example, the stones used in an Imu (Hawaiian Underground Oven) can be 400F or warmer. This is 330F above ambient temps (or more) while water can only go 142F above 70F ambient.

However, putting extremely hot stones in your bath isn't good for sous vide either because it will just make the water boil and what you want is fine temperature control at a specific temperature. So for sous vide purposes, stones and ceramics are impractical.