All this speculation about water leads me to some questions.

It would seem that water would form a larger percentage of the total mass at a certain distance in a proto-planetary system.

(I also am led to wonder whether or not the planets surrounding the near-star planet Jupiter demonstrate regular differentiated elemental compositions.)

Assuming a regularly differentiated distribution of elements for the time being, it is also clear that at different distances from a sun the planets will then be affected by the processe of that star itself; this will sometimes cause the water that has accumulated on them to dissipate, be lost back into the system as a whole.

If you could break this out by probability, in other words given the elemnental dsitribution on a probabilistic curve, and the ditto fo the mass distribution, then you have a rough estiamte of the frequency of water planet formation and continuance.

If you could break this out by star types, then you have a rough starting population.

Next comes the differentiation of water and land on these planets. As Hoffman has pointed out, a fairly massive moon can do this. Other mechanisms may include another planet in a nearby orbit, or even a large enough impact will raise a land mass for quite a while.

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