Gripe
The most dense of the two forms of concrete is 65 pounds per cubic foot while the less dense is a mere 30 pounds per cubic foot. These physical attributes give the concrete boat its ability to float, considering that water is 62.5 pounds per cubic foot.
Concrete boats don't float because the concrete used is less dense than water; they float because the boats weigh less than the water they displace. The hulls of boats are regularly made with materials denser than water. If you cut off a piece of the hull of a large boat and dropped it into the water, it would likely sink.
Another gripe: Spirit, Southwest Airlines' in-flight magazine, had a piece this month complaining about how most Americans can't identify the Constitution's guarantee of "life, liberty, and the pursuit of happiness". Maybe that's because it was the Declaration of Independence.
