Circle of death (boating)

Last updated

The circle of death is a hazardous phenomenon experienced by motorboats.

A circle of death can be initiated if the boat operator releases the steering mechanism while the boat is still powered, which means the propeller is still turning. The force of the rotating propeller blades incurs a force known as steering torque, causing the motor itself, which is mounted on a swivel jointed mechanism, to turn sharply into the direction of the blades. This causes the boat to cut sharply to the opposite direction, which can throw the operator and any passengers overboard. The boat then begins spinning in circles, oftentimes around the ejected passengers, who are in danger of being struck by the spinning propeller over and over again. [1] [2] [3] [4]

The most common preventative safety recommendation, aside from simply ensuring maintained control of the wheel while the vehicle is in motion, is the installation of an automatic kill switch. [4] [2]

Related Research Articles

<span class="mw-page-title-main">Propeller</span> Device that transmits rotational power into linear thrust on a fluid

A propeller is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon a working fluid such as water or air. Propellers are used to pump fluid through a pipe or duct, or to create thrust to propel a boat through water or an aircraft through air. The blades are shaped so that their rotational motion through the fluid causes a pressure difference between the two surfaces of the blade by Bernoulli's principle which exerts force on the fluid. Most marine propellers are screw propellers with helical blades rotating on a propeller shaft with an approximately horizontal axis.

<span class="mw-page-title-main">Parasailing</span> Aerial manned-kite sport

Parasailing, also known as parascending, paraskiing orparakiting, is a recreational kiting activity where a person is towed behind a vehicle while attached to a specially designed canopy wing that resembles a parachute, known as a parasail wing. The manned kite's moving anchor may be a car, truck, or boat. The harness attaches the occupant to the parasail, which is connected to the boat, or land vehicle, by the tow rope. The vehicle then drives off, carrying the parascender and person into the air. If the boat is powerful enough, two or three people can parasail behind it at the same time. The parascender has little or no control over the parachute. The activity is primarily a fun ride, not to be confused with the sport of paragliding.

<span class="mw-page-title-main">Vehicle</span> Mobile equipment that transports people, animals or cargo

A vehicle is a piece of equipment designed to transport people or cargo. Vehicles include wagons, bicycles, motor vehicles, railed vehicles, watercraft, amphibious vehicles, aircraft and spacecraft.

<span class="mw-page-title-main">Jetboat</span>

A jetboat is a boat propelled by a jet of water ejected from the back of the craft. Unlike a powerboat or motorboat that uses an external propeller in the water below or behind the boat, a jetboat draws the water from under the boat through an intake and into a pump-jet inside the boat, before expelling it through a nozzle at the stern.

<span class="mw-page-title-main">Skid-steer loader</span> Compact heavy equipment with differential steering

A skid loader, skid-steer loader, SSL, or skidsteer is any of a class of compact heavy equipment with lift arms that can attach to a wide variety of buckets and other labor-saving tools or attachments.

<span class="mw-page-title-main">Darrieus wind turbine</span> Type of vertical axis wind turbine

The Darrieus wind turbine is a type of vertical axis wind turbine (VAWT) used to generate electricity from wind energy. The turbine consists of a number of curved aerofoil blades mounted on a rotating shaft or framework. The curvature of the blades allows the blade to be stressed only in tension at high rotating speeds. There are several closely related wind turbines that use straight blades. This design of the turbine was patented by Georges Jean Marie Darrieus, a French aeronautical engineer; filing for the patent was October 1, 1926. There are major difficulties in protecting the Darrieus turbine from extreme wind conditions and in making it self-starting.

<span class="mw-page-title-main">Steering</span> The control of the direction of motion of vehicles and other objects

Steering is the control of the direction of locomotion.

<span class="mw-page-title-main">Dead man's switch</span> Equipment that activates or deactivates upon the incapacitation of operator

A dead man's switch is a switch that is designed to be activated or deactivated if the human operator becomes incapacitated, such as through death, loss of consciousness, or being bodily removed from control. Originally applied to switches on a vehicle or machine, it has since come to be used to describe other intangible uses, as in computer software.

Automobile handling and vehicle handling are descriptions of the way a wheeled vehicle responds and reacts to the inputs of a driver, as well as how it moves along a track or road. It is commonly judged by how a vehicle performs particularly during cornering, acceleration, and braking as well as on the vehicle's directional stability when moving in steady state condition.

<span class="mw-page-title-main">Kill switch</span> Safety mechanism to quickly shut down a system

A kill switch, also known more formally as an emergency brake, emergency stop (E-stop), emergency off (EMO), or emergency power off (EPO), is a safety mechanism used to shut off machinery in an emergency, when it cannot be shut down in the usual manner. Unlike a normal shut-down switch or shut-down procedure, which shuts down all systems in order and turns off the machine without damage, a kill switch is designed and configured to abort the operation as quickly as possible and to be operated simply and quickly. Kill switches are usually designed to be noticeable, even to an untrained operator or a bystander.

<span class="mw-page-title-main">Pilatus PC-12</span> Swiss executive and utility transport aircraft

The Pilatus PC-12 is a pressurized, single-engined, turboprop aircraft manufactured by Pilatus Aircraft of Stans, Switzerland since 1991. It was designed as a high-performance utility aircraft that incorporates a large aft cargo door in addition to the main passenger door. Due to its efficient, high-utility design, the PC-12 is used by a large variety of operators. The main use for the aircraft is corporate transportation, but it is also used by fractional and small regional airlines, air-ambulance operators, and many government agencies, such as police departments and armed forces. The PC-12 is successful with 2,000 deliveries made as of May 2023.

<span class="mw-page-title-main">Conventional landing gear</span> Aircraft undercarriage

Conventional landing gear, or tailwheel-type landing gear, is an aircraft undercarriage consisting of two main wheels forward of the center of gravity and a small wheel or skid to support the tail. The term taildragger is also used, although John Brandon of Recreational Aircraft Australia argues it should apply only to those aircraft with a tailskid rather than a wheel.

<span class="mw-page-title-main">Countersteering</span>

Countersteering is used by single-track vehicle operators, such as cyclists and motorcyclists, to initiate a turn toward a given direction by momentarily steering counter to the desired direction. To negotiate a turn successfully, the combined center of mass of the rider and the single-track vehicle must first be leaned in the direction of the turn, and steering briefly in the opposite direction causes that lean. The rider's action of countersteering is sometimes referred to as "giving a steering command".

<span class="mw-page-title-main">Airboat</span> Type of watercraft propelled by an aircraft propeller

An airboat is a flat-bottomed watercraft propelled by an aircraft-type propeller and powered by either an aircraft or automotive engine. They are commonly used for fishing, bowfishing, hunting, and ecotourism.

Blade pitch or simply pitch refers to the angle of a blade in a fluid. The term has applications in aeronautics, shipping, and other fields.

<span class="mw-page-title-main">Variable-pitch propeller (aeronautics)</span> Propeller with blades that can be rotated to control their pitch while in use

In aeronautics, a variable-pitch propeller is a type of propeller (airscrew) with blades that can be rotated around their long axis to change the blade pitch. A controllable-pitch propeller is one where the pitch is controlled manually by the pilot. Alternatively, a constant-speed propeller is one where the pilot sets the desired engine speed (RPM), and the blade pitch is controlled automatically without the pilot's intervention so that the rotational speed remains constant. The device which controls the propeller pitch and thus speed is called a propeller governor or constant speed unit.

Self-steering gear is equipment used on sail boats to maintain a chosen course or point of sail without constant human action.

<span class="mw-page-title-main">Marine propulsion</span> Systems for generating thrust for ships and boats on water

Marine propulsion is the mechanism or system used to generate thrust to move a watercraft through water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting of an electric motor or internal combustion engine driving a propeller, or less frequently, in pump-jets, an impeller. Marine engineering is the discipline concerned with the engineering design process of marine propulsion systems.

<span class="mw-page-title-main">Wind-powered vehicle</span> Vehicle propelled by wind

Wind-powered vehicles derive their power from sails, kites or rotors and ride on wheels—which may be linked to a wind-powered rotor—or runners. Whether powered by sail, kite or rotor, these vehicles share a common trait: As the vehicle increases in speed, the advancing airfoil encounters an increasing apparent wind at an angle of attack that is increasingly smaller. At the same time, such vehicles are subject to relatively low forward resistance, compared with traditional sailing craft. As a result, such vehicles are often capable of speeds exceeding that of the wind.

The number of personal watercraft-related accidents has increased with the popularity of personal watercraft (PWC) since their introduction during the late 1960s. The use of the term "jet ski" for all types of PWCs is a misnomer; Jet Ski is a registered trademark in the United States for a line of PWCs manufactured by Kawasaki). With the increased use of personal watercraft since their inception, the hazards accompanying their use have also increased. According to U.S. government reports, most accidents are associated with rental operators, underage operators, under-trained and undereducated boaters and a variety of factors associated with recreational-boating accidents. Due to their affordability, ease of use, and relatively low transportation and maintenance costs, personal watercraft have significantly increased the number of water-based enthusiasts in the U.S. This rise in participation has created conflicts between the various boating segments in the U.S. and a need for additional boater education. Recreational-boating accidents are the second-largest transportation-related cause of injury in the U.S..

References

  1. "Minnesota Boating Guide 2023 (Section: "The Circle of Death")" (PDF). Retrieved August 29, 2023.
  2. 1 2 "Boating Safety Course - Propeller Strike". boatingbasicsonline.com. Retrieved April 17, 2016.
  3. "The Circle of Death - Propeller Strike Injuries". www.boat-ed.com. Retrieved April 17, 2016.
  4. 1 2 Boating & Water Safety (PDF). Saint Paul, MN: Minnesota Department of Natural Resources. 2014. p. 5.