Statement of Dr. Kenneth Fisher Regarding the Utilization of Propeller Guards on Selected Boat Types

Dr. Kenneth Fisher, President of the Fisher Maritime Consulting Group, asserted that propeller guards are appropriate for at least one particular class of motorboats. He also indicated that alternative technologies, such as waterjets, could be used to obtain the same benefits. His statements were made in the course of a deposition on January 26, 2005. He identified waterski boats used in tournaments as the type of boat for which a propeller guard is essentially necessary, while having minimal adverse impacts. The case involved the loss of a hand and other injuries sustained by Christie Melvin Gray while swimming in a lake in Alabama in July 2001 when she was stricken by a boat designed for use in waterski tournaments.

According to Dr. Fisher, a boat designed and manufactured for participation in waterski tournaments is certain to be used in the vicinity of persons in the water, regardless of whether it is actually in a tournament or is being used for recreational purposes. Thus, the potential hazard of contact between a person and the propeller is clearly identified and is substantially higher than for boats that are not designed for waterskiing use.

The propulsion system of the waterski boat, including the engine, shafting and propellers, is sized to achieve rapid start-up and planing of the boat and skiers. That is, it is sized for its initial thrust while at low speed. The maximum speed of the boat is a by-product of the propulsion system that is designed for that initial lift-off. That maximum speed far exceeds the speed that is needed in waterski tournaments. It also exceeds the speeds that are reasonably safe for towing waterskiers. Thus, says Dr. Fisher, any reduction in top speed of a waterski boat due to a propeller guard will not affect the ability of the boat to be used in or accepted for waterski tournaments.

The maneuvers that a boat must make in a waterski tournament are not dramatic, since it is not intended to cause the waterskiers to be whipped around the course. Due to their significant power and broad propeller blades, the maneuverability of the waterski boats far exceeds that required in waterski tournaments. Thus, if the propeller guard has any adverse impact on the maneuverability of the boat, the boat will still have more-than-sufficient maneuverability for the waterski tournament.

Dr. Fisher acknowledged that there will be a slightly greater fuel consumption rate. This is consistent, he said, with the fact that boats and other modes of transportation, such as automobiles, experience greater fuel consumption due to the weight of safety mechanisms that are built into the vehicles. On boats, positive flotation, bilge pumps, fire extinguishers, bilge blowers and other required safety devices already add to the weight of the boat and thus reduce its fuel efficiency. On automobiles similar safety mechanisms include seat belts, air bags, sidewall impact protection, emissions controls, and heavier bumpers to avoid low speed impact damage, among other weight and cost penalties that are incurred in automobiles for the benefit of safety.

Although a propeller guard on a speeding boat may cause blunt trauma if it strikes a person, Dr. Fisher noted that the propeller blade tip speed is going 2 ½ to four times as fast as the linear speed of the boat. Also, he stated, the leading edge of the propeller blade is sharper than the leading edge of a propeller guard device. Thus, the blunt trauma injury from the linear speed collision with the propeller guard is certain to be less catastrophic than the cutting injury from the higher speed propeller blades. He opined that whereas such blunt trauma may result in bone fractures and soft tissue injury from which recovery is likely, the propeller blade injury is almost certain to cause the severing of appendages from which there little likelihood of recovery.

The boating public, he asserted, will not resist purchasing waterski boats with propeller guards because of any adverse impacts, as long as it can be demonstrated that the boat remains qualified for waterski tournaments. The incorporation of propeller guards or alternative technologies on waterski boats means that the safety features are built-in, and do not rely on the continuous observations and control by the boat operator.