The U.S. Navy tried to build a new frigate. It didn’t go well.After years of delays, design changes, and billions of dollars spent on the Constellation-class, the Navy is hitting reset, and this time it’s doing something surprisingly unglamorous: copying a Coast Guard cutter that already exists, already sails, and already works.The Navy’s next frigate is based on the Coast Guard’s Legend-class National Security Cutter. On paper, that sounds like a step backward. In reality, it might be one of the smartest shipbuilding decisions the Navy has made in years…if it can resist the urge to overcomplicate it.