Trying to remember a scifi novel where the warships were protected in part from enemy lasers and such by superconductive shielding that was in turn connected to a superconductive wire run through a tank of ice or water, the thermal mass of which helped dissipate the impact/ heat.

For years I was sure that this book was The Mote in God's Eye, and while there is a brief reference to something similar in the sequel The Gripping Hand, it wasn't there in Mote.

Anyone have any clue what the book is? Is it possible this conceit was in an early edition of Mote, but not later ones? Know I read this when I was younger and didn't just imagine it.