What I find interesting is the material contemplated was a composite of wood pulp and ice.
When I taught engineering materials, I gave a home work assignment for the students to make composites of ice and materials of their choice. We then Charpy tested them, quickly. Before I assigned this I first made one of frozen Jell-O. I'm still amazed at what a little gelatin does for ice.
DEFENSE TECH - As the Allies prepared to invade occupied Europe in 1942,
a truly nutty idea swept through the British military hierarchy: build
giant aircraft carriers made of ice. The ships could be made cheaply,
they figured. And, maybe, they could be constructed tough enough to
withstand bullets and torpedoes.
With Churchill's blessing, Lord Louis Mountbatten, Chief of Combined
Operations, began the task of developing "berg-ships" up to 4,000 feet
long, 600 feet wide and 130 feet in depth. . .
TOM SHACHTMAN, LABORATORY WARRIORS - To my mind, the major interest of
the story of this absurd enterprise is how far it went before the bubble
was burst. This was a loony idea all along, and its premise was easily
refuted by science and even easier by mathematics -- you just had to
compute how much of the stuff would be needed to make a floating
airfield, plug in a few figures about the output of wood from Canadian
forests, and realize that it would take the entire country's forests to
make one field. But because the idea had powerful patrons, Churchill and
Mountbatten, who were not scientists but politicians whose authority
could direct the spending of millions of taxpayer dollars, millions of
dollars were spent on it. It reminds us that Star Wars is not the only
science-fiction fantasy to enchant the mind of a leader of the Western
world.