Posted: June 1, 2012
Suzuki’s new outboard prop can spin in both directions.It was one of those ideas that had us, the judges of the 2012 NMMA Innovation Awards, smacking our forehead with the palm of our hand as we thought, “Why didn’t anyone think of this before?” With the unveiling of the DF300AP Selective Rotation outboard at the 2012 Miami Boat Show, Suzuki made it unnecessary to buy two different models of outboards to spin the props in opposite directions on twin-engine-or-more boats.
Before, boat dealers and consumers with multi-engine rigs had to buy a separate left-hand-rotation outboard for the port side — which can cost nearly $1,000 more since fewer are made in order to negate the prop torque from the right-rotating outboard. Now, consumers can save money up front and later, because when it’s time to repower and sell the old outboards, they won’t have to insist the engines go as a pair like animals on the Ark. They can sell one at a time and not have to worry about getting stuck holding a lefty, which are in less demand than righties and command less money on the used market. To summarize: Counter-rotational models cost more new but are worth less used. They’ve got you coming and going … until now.
For Suzuki dealers, it means having to stock fewer motors. Previously, they had to stock four different models for the Suzuki DF300: 25- and 30-inch-shaft models in both clockwise and counterclockwise rotations. Now, they only need two. From Suzuki’s standpoint, logistics are far easier, since the company doesn’t have to predict demand as accurately, giving it a better chance of keeping those in its supply line happy.
So Easy a Caveman Can Do It
So, you’re probably thinking you have to take it to a mechanic and let him operate on it to change the rotation, right? Actually, it takes about one minute to accomplish, and anyone can do it. Just take off the cowling and unplug a wire connector — and the next time you shift, the rotation is changed. How Suzuki designers did it is pretty clever. They beefed up the reverse gear and gave it the same characteristics as forward. And because the DF300 is an electric-shift model, the switchover is easy: When you push the drive-by-wire throttle forward, the gears engage in reverse, but with a counter-rotating prop mounted, the boat is pushed forward. The ease of the change creates the additional benefit that you don’t have to carry two spare props, since you can just switch the rotation to match the prop you’re using.
While the engineers were reconfiguring the gears, they also improved the lower unit. Hydrodynamically slipperier, it now sports four water inlets instead of the two on previous DF300 models, which makes it more desirable for people who use jackplates, because it can run shallower and still obtain sufficient water to stay in an unfried state.
Because Suzuki’s DF300 sports the lowest gear ratio in its class, at 2.08:1, it can swing a bigger-diameter prop to push more water. That’s why they are often chosen to push heavy loads such as commercial bait boats that have livewells that hold several hundred gallons. A larger prop also translates into a better holeshot.
Taking a few lessons from racing technology, Suzuki uses a Variable Valve Timing (VVT) system to achieve a higher level of performance. Most engines have camshafts that are optimized for one range of speeds, giving you better performance where you spend most of your time. With VVT, the timing can vary as much as 40 percent in order to create overlap between the intake and exhaust valves when the hammer is down, to optimize holeshot without adversely affecting top-end performance.
One of the improvements over the original DF300 is the use of the Lean Burn Control System, first implemented on the DF90/80/70. Lean Burn ensures the air/fuel mixture changes in response to the load placed on the engine. During acceleration, the mixture is richer for better performance, but as the boat settles into cruise speed, the mixture becomes leaner for up to 14 percent better economy than the original DF300.
Suzuki uses an offset driveshaft to move the center of gravity closer to the transom, for better balance and less vibration. It also reduces the overall size and offers less of an obstacle for fishermen trying to corral a rampaging fish at the transom. Another plus for anglers is the inclusion of Troll Control, which allows you to fine-tune your trolling speed in 50 rpm increments up to 1200 rpm.
Suzuki’s engineers believe there’s “no replacement for displacement” when trying to create power easily, and they put this philosophy to use by giving the V-6 DF300AP a large 4.0L block. To make it easier on the owner, it has a no-maintenance self-adjusting oil-bathed timing chain instead of a timing belt.
For the Boating Writers International judges, the addition of Selective Rotation made our job of selecting an outboard to win the Innovation Award a no-brainer — chalk up a seventh trophy for Suzuki.