[Steely Tom]

I believe that the spaceship on which much of the action of Heinlein's Podkayne of Mars used water as a radiation shield. It was written in the early 1960s.

[Jack Hydrazine]

http://en.wikipedia.org/wiki/Podkayne_of_Mars

Podkayne of Mars is a science fiction novel by Robert A. Heinlein, originally serialised in Worlds of If (November 1962, January, March 1963), and published in hardcover in 1963. The novel is about a teenage girl named Podkayne “Poddy” Fries and her younger, asocial genius brother, Clark, who leave their home on Mars to take a trip on a spaceliner to visit Earth, accompanied by their uncle.

http://worldtracker.org/media/library/English%20Literature/H/Heinlein,%20Robert%20A/Robert%20A%20Heinlein%20-%20Podkayne%20of%20Mars.pdf

[PA Engineer]

I believe that the spaceship on which much of the action of Heinlein's Podkayne of Mars used water as a radiation shield. It was written in the early 1960s.

I hadn't read it. I guess great minds think alike. ;-)

I had sketched out a lightweight honeycomb panel design using electroosmosis to recycle the water. Oh well.