[PA Engineer]

The spacecraft has been notionally described as using a large water store to help shield occupants from space radiation

Darn. That was my idea decades ago. Should have patented it and shashimied it every 14 years.

[Jack Hydrazine]

Future Spacecraft Could Protect Crews With Walls Made of Water
http://www.popsci.com/technology/article/2012-09/future-spacecraft-could-protect-crews-walls-made-water

Radiation shields, new engines mandatory for Mars
http://www.spaceflightnow.com/mars/msl/130530rad/#.U3wEwyhr2og

[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.