Aboard our Midnight Express 39 test boat, triple 557s pulled with exhilarating acceleration and the screaming sound of a jet fighter, peaking at 105 decibels at wide-open throttle. They are louder than other triple outboards in our boat test database. Think “satisfying roar.”
During factory trials, Seven Marine pushed this 39-footer to 81 mph, a credible number. We ran with a full gas tank and a crew of four. Plus, our test boat’s owner ordered the boat set up for cruising rather than speed. And Seven is in the process of optimizing the engine’s computer mapping.
Triple 557s with joystick steering cost $270,000 for 1,671 hp. You’d need five 350 hp outboards to match it, a power package weighing up to 22 percent more. Five outboards would also require more rigging, and a quintet of gear cases would generate more drag. Yet, you can buy five 350s (without joystick) for between 42 and 45 percent less than the triple 557s’ cost.
Still, Seven Marine’s 557 is an engineering triumph: the world’s most powerful outboard.