Ride Technology | PWC Off-Throttle Steering Loss

Off-Throttle Steering Loss (OTSL) occurs when a PWC operator, faced with a potential collision hazard, attempts to slow and turn the craft by releasing the throttle and turning the handlebars away from the hazard. Because of their jet-pump design, most PWC do not provide steering control under these circumstances. The result is that the craft continues on a straight course directly towards the hazard, regardless of the operator’s steering inputs. According to the National Transportation Safety Board (NTSB), 24% of reported PWC accidents have steering problems or loss of control as contributing factors. In Florida it is the second leading cause of PWC accidents.

PWC manufacturers claim that this loss of steering control is inherent in any jet-pump design and that operators are to blame for improper use of PWC. However, at least 80% of PWC operators have had prior boating experience. And 70% of PWC accidents are collisions, with 70% of those being collisions with other PWC. In other words, half (50%) of all PWC accidents are collisions with other PWC, implying that there is something inherently different about PWC compared to traditional recreational powerboats. That something is the loss of steering control under circumstances when it is needed the most - just prior to a collision. This counterintuitive steering response also occurs when the engine is off. Off-engine scenarios are easy to envision and include, among others, inadvertent pulling of the lanyard, engine failure, and intentional use of the stop button. The ability to provide steering control during off-throttle and off-power conditions is known as collision avoidance.

OTSL is counterintuitive for two reasons. First, we have been conditioned by many common forms of transportation to expect steering control to be present and available under normal conditions. Cars, trucks, bikes, skateboards, roller skates, rollerblades, snowmobiles, ATVs, motorcycles and even snowboards provide steering control during off-throttle and off-power situations. Additionally, all motorized forms of transportation provide both steering and braking simultaneously. Second, OSTL is counterintuitive because it goes against our instinctual “fight or flight” response. Attempting to avoid a collision obviously falls under the “flight” response, but traditional PWC require the operator to accelerate towards the hazard, thus going against our instincts.

Many organizations have become involved in PWC collision avoidance including NASBLA, USCG, NTSB, ABYC, SAE and UL. The Coast Guard is currently working with PWC manufacturers to create a voluntary industry performance standard.

Prior to this the USCG formed a PWC Advisory Panel under the American Boat & Yacht Council (ABYC) to study the need for an OTS standard. This panel concluded that a PWC OTS Performance Standard was needed. All PWC manufacturers and the Personal Watercraft Industry Association (PWIA) voted in favor of the need for an OTS standard. During discussions it was determined that a braking (controlled deceleration) devices could also be used to prevent a potential collision. Therefore the term Off-Throttle Steering was replaced by the more general term Collision Avoidance.

The USCG then issued a grant to Underwriter’s Laboratories (UL) in May 2000 to test available collision avoidance technologies and develop a performance standard for PWC collision avoidance. The final UL test report and proposed standard is expected to be released in the near future. A preliminary draft of the Collision Avoidance performance standard was issued by UL in October of 2001.

The PWC industry (all except for Sea Doo) have created their own proposed performance standard based on the UL standard. However the industry-sponsored standard is significantly weaker than the UL standard. In addition to stretching out the distances considerably the industry has neglected the novice rider who is most likely involved in this type of accident, stand up riders who face the most difficult type of PWC to operate and all operators in off-power situations.

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 with the intention of licensing it to its former competitors. For the 2001 model year Kawasaki introduced its SmartSteering™ system on two of its high-end models. Kawasaki’s system is similar to the ArcticCat’s but is deactivated at low speed, presumably to facilitate docking maneuvering. Kawasaki markets this throttle reapplication technology as a training device which reminds 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 left or right.

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

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.