Water 101

The basic Physics of Water as they pertain to EPS cored Boards



Its just water, right? Simply H2O. Well, not exactly...

The water molecule is asymmetrical, where the two hydrogen atoms are attached to the oxygen atom like the big feet to the body of my little waterman perched above. This makes the molecule positive on the hydrogen side (the feet), and negative on the oxygen side (the head). Put lots of these lopsided, "magnetic" molecules together, and they will form intricate structures.

Up to about 40deg C, water really is mostly H4O, a tetrahedral structure with four triangular sides. Two hydrogen atoms belong to the first O atom, while the other (2) H are shared with the neighboring O atom, which shares (2) H atoms with its neighboring O atom, which shares .... etc etc, making up the lattice structure of water.

All molecules are constantly moving. Heating the water increases this motion, straining the hydrogen bonds. Heating water beyond 40 deg C increasingly breaks the hydrogen bonds, breaking the lattice structure into chains.

All types of water intrusion will be more severe the warmer the water, since the warmer water molecule is smaller. Surveying boats with osmotic blisters, for example, I can almost invariably tell which side normally faced South when in the slip.

To evaporate water, that is, to change it from a liquid into a gas, requires enough energy to overcome the hydrogen bonds altogether and allow molecules to escape the liquid. At sea level, it requires 540 calories of heat to evaporate 1 gram of water.

To evaporate water also requires a vertical moisture gradient. If evaporated water vapor is allowed to hover over the liquid, newly evaporating molecules with bounce off and back into the liquid, preventing further evaporation. To speed evaporation, then, air flow should be directed over the liquid surface to remove the humid layer (think of your Spinning class, where you are miserably hot until someone turns on the fans). The dryer this air is, the more it will increase the vertical moisture gradient, the more it will speed evaporation (if only someone would open the door to the Spinning room!).

The stick-to-it-ness of the water molecules creates surface tension, makes water form beads, and causes  capillary action, where water "climbs" the fibers of a paper towel, until gravity gets stronger than the hydrogen bonds.

And one last law to remember: 

When temperature increases, the higher molecular motion in water vapor results in expansion of volume.

This is why it is so vitally important to keep the innards of our boards as dry as possible. This is why it is so vitally important to always exercise the vent plug once you have had water in your core

return to water, water everywhere