Ride Technology | Collision Avoidance Technologies

Collision avoidance technologies fall into two categories, depending on the conditions under which they operate: off-throttle or off-power. Rudders and brakes operate during both off-power and off-throttle operation, relying on the flow of water past the hull to generate turning forces. Throttle reapplication technologies work only during off-throttle operation by increasing engine RPMs when off-throttle steering loss is detected. They require the engine to be running and consequently do not work during off-power conditions. Off-Power scenarios are easy to envision and include the inadvertent pulling of the lanyard, hitting the stop button, going onto reserve (low fuel), ingesting a stick in the pump and motor failure due to low oil or overheating.

Rudders provide both braking and steering, as called for in the NTSB study. Brakes, also known as deceleration devices, provide braking but no steering. Throttle reapplication technologies provide steering but no braking.

In addition to WaveTrax, there heave been several other PWC rudder systems including JetFin, Hidrofin, Murray blowback ruder, two Yamaha patents and the Sea Doo Off Power Assisted Steering (OPAS) system.

In order to be effective as a collision avoidance device, brakes would need to provide the operator with control over the amount of deceleration provided. A brake deployed at high speed will generate more deceleration than at low speed. There are two problems with brakes; 1) the operator must reach for the brake lever — this requires time to make the correct decision and then to reach for and pull the lever. 2) Brakes generally rely on spring tension to deactivate the brake. Once deployed, they remain open until the craft has slowed sufficiently to allow the spring tension to overcome the water pressure flowing into the brake. One company, poised to enter the PWC market found a solution to this problem.

When Mercury Marine was preparing to enter the PWC market, engineers for Brunswick, its parent company, developed an active braking system that leverages the thrust from the pump to control deployment of reverse thrust. Since this system relies on pump thrust, unlike other deceleration devices it does not work during off-power conditions.

The first PWC manufacturer to publicly demonstrate an OTS device did so well after abandoning the marketplace. ArctiCat, former manufacturer of the TigerShark line of PWC, introduced a throttle reapplication device apparently with the intention of licensing it to former competitors. For the 2001 model year Kawasaki introduced its SmartSteering™ system on two of its models. Kawasaki’s system is similar to the ArcticCat’s but is deactivated at low speed, presumably to facilitate docking maneuvers. Kawasaki markets this throttle reapplication technology as a training device to remind operators when to apply throttle. This design uses sensors to detect the occurrence of OTSL: a sudden release of the throttle from high speed coupled with the handlebars being turned all the way to the right or the left.

Once these two events are detected, the electronic engine control signals the motor to increase speed to a certain RPM for a specified time period. Even though Kawasaki is promoting this as a training device, it is clearly an OTS device. One PWC magazine reported of it: “The system will help riders... and may reduce the chances of collisions during throttle-off emergencies.”

Honda implemented a throttle reapplication technology on both of its AquaTrax™ models when it entered the market in 2002. This design also features a programmable limit mode that Honda claims will allow the operator to match the craft’s performance to his or her skill level.

The throttle reapplication systems from Kawasaki and Honda do not provide any additional steering control under off-power or off-engine conditions. In 2002 Sea Doo introduced the Off Power Assisted Steering (OPAS™) system on four of its models and plans to have the system on all models in 2003. This dual-rudder design provides both steering and braking during deployment. The OPAS system uses pump pressure to raise the rudders out of the flow of water and springs to lower them as the throttle is released and the pump spools down.