Charles W. Robinson has a new type of boat for sale. She's called the M80 Stiletto, and she looks like something out of a Batman movie. Her distinctive double-M–shaped hull, made of tough carbon fiber, gives her a top speed of 50 knots (about 60 mph) and a smooth ride in the roughest of seas. Robinson says her agility and stealthy profile make her ideal for Navy SEAL operations in shallow coastal waters. And at $6 million, she's a bargain by military-industrial standards. "There's a great video of her on YouTube," he adds, speaking by phone from his home office in Santa Fe, N.M.