From topside, the Navy's future USS America looks picture-perfect, its hull shimmering as it slices through the waves. But below deck, one of the ship's electric motors won't start. To keep moving, the captain has had to fire gas-guzzling engines. For days like this, the Navy is missing one of its best men: Retired Cmdr. Michael Arnold — one of 12 people killed in last year's Navy Yard shooting rampage in Washington.