This 1919 pamphlet's title certainly sound more odd than the concept it describes: concrete boats have been around for a long time, (160 years at least), and they make a lot more sense than a quick-think would give them (lumbering, unstoppable, heavy prep trucks come to mind). For boats over 25 feet long, it is probably the easiest and cheapest material to employ, and it doesn't need weatherproofing. And, as an interesting website dedicated to concrete boats (ferro-boats) observes, a 30-foot 8-ton displacement ship made of either wood or concrete will weigh the same, which means that the very first image that comes into our heads when you say "concrete ship" is just wrong.
It looks like the French were the first to come up with the idea in about 1848, patenting the most winning methods of construction in 1855. Since then there have been 12,000 or so of these 25-ft+ ships built, including a 130' yacht and a 120' British sub. This method of construction certainly saw its time, especially during wartime, when steel production was in high demand.
Please note: posts over the next seven days or so will be somewhat truncated; I'm moving my store so time is a little scarce. Thanks for bearing with me.