Suzuki Selective Rotation - a world-first in outboard technology

by Martin Beeson The Haines Group on 31 Jan 2012 Suzuki has taken the lead once again in pioneering cutting edge outboard motor technology with the introduction of Suzuki Selective Rotation.

When installing two or more outboards to the transom of a boat a combination of regular rotation and counter rotation units is normally used, which currently means using two separate outboard models - a regular rotation model and a counter rotation model.

Now, in a move that will please customers, dealers and boat builders Suzuki has announced the introduction of Suzuki Selective Rotation. This means that one outboard model can operate in either regular or counter rotation modes.

For those not familiar with the reason for a counter rotating model the reasoning is simple. In most applications when a boat requires twin engines to power and push it, the port side engine must use a counter rotation lower unit (often referred to just as gearbox) and the starboard engine uses a normal clockwise rotation lower unit. In a twin engine application this must be done so that the propellers are spinning in different directions. The reason for this is:

- Less ‘dirty’ water being drawn from each propeller causing ventilation (air around the blade area).
- Reduces the tendency for a boat to list to the starboard due to propeller torque pushing it that way.
- Enables larger boats to manoeuvre at low speed for docking.
- Reduces the harmonics and transfer of hull vibration and noise in the boat.

The negatives of having a counter rotation engine is:
- The resale value of a counter rotating model engine is far lower than a normal engine.
- Customers do not like purchasing a single counter rotation engine for their boat.

The new Suzuki DF300AP is the first outboard or stern drive leg in the world which can operate in either forward (clockwise) or reverse (anti clockwise) direction. This type of lower unit will eventually be available in smaller horse power models in the future.

This technology will first be introduced on the new DF300AP. In its standard form, this new model will operate in regular clockwise rotation, using the forward gear. Now, by changing the gear-shift mode and adding a counter rotational propeller, the same outboard can operate in counter rotation mode (anti-clockwise).

In counter rotation mode the power is transmitted through the reverse gear, which has been upgraded and improved to give it the same characteristics as the forward gears. In fact, the specifications and materials used for forward and reverse gears have both been optimised, as well as improving the layout of the bearings.

In order to accommodate the new gear system and taking the opportunity to add even more new features to the new DF300AP, the Suzuki engineers have also re-designed the gear case.

By using accumulated fluid analysis technology the new gear case has been designed to provide reduced resistance and improved durability. At the same time, a structural analysis was carried out in order to optimise each and every component. However, the Suzuki engineers did not stop there with the improvements. The new DF300AP has been designed with two water intakes on each side of the gear case - the current DF300 has just one on each side. The additional water intakes ensure stable cooling performance at high speeds and also during operation in shallow water.

Ultimately, by eliminating the differences in specification between regular and counter rotation models, Suzuki has achieved what no other outboard manufacturer has been able to do - unification of both regular rotation and counter rotation operations into a single outboard model.

The DF300AP will be available in Australia and New Zealand in March 2012.