MARINE
Boat Propeller Strike Protection
Carbon Monoxide — The Silent Killer
ATA Studies Houseboat Asphyxiation Danger
ATA Conducts Boat Tests in Louisiana
ABYC Announces Formation of New Committee
Boating Safety
by Richard Akers, P.E.
Boating is the perfect way to cool off during the hot, humid dog days of summer. However, there are many factors that when coupled with boating add up to serious trouble. Operator judgment can be affected by lack of training or knowledge, too much sun and activity, and possibly too much alcohol consumption.
Because recreational powerboats have become more affordable, the risk of unskilled boat operators has greatly increased. This fact introduces potential danger not only to the passengers of that boat, but sadly and unfortunately to anyone on the water.
There is an unending list of accident causes on the water – boats appearing unexpectedly from side channels, debris in the water or rocks just below the surface, the wake of other vessels, and even obstacles such as tug-barge hawsers (tow-lines).
Whereas, a person driving a car at high speeds can swerve to avoid an accident, it is entirely different in a boat. A boat traveling at 60 miles per hour will have a turning radius of several hundred feet, so the operator has to anticipate all potential accidents because he cannot easily swerve out of harm’s way. And it is routine to see production boats that can exceed 60, 70, even 100 miles per hour.
In the last decade jet-propelled boats and personal watercraft (PWC) have become very popular. These vessels are turned by redirecting the jet blast, so the side force in a jet boat or PWC occurs only when the jet is running. If you take your hand off the throttle and the engine stops, there is no side force to turn the vessel (unlike a propeller-driven boat where the rudder or drive housing still produces a side force that can turn the boat if it suddenly loses power). Tests have shown that a typical personal watercraft traveling 50 MPH (slow for a modern PWC) will require in excess of 200 feet to glide to a stop. The inexperienced PWC operator heading toward a group of picnicers on shore could panic, throttling back while attempting to turn, not realizing that when the engine is idling they cannot turn or stop in time to avoid an accident. The absence of "off-throttle steering" and lack of training or experience results in many boating accidents.
The phenomenon of “porpoising” is also a common cause of boating accidents. A boat is porpoising when it is pitching up and down as it moves forward and when there is no surface disturbance causing the motion. This vertical instability is possible in almost all high-speed planing craft and can cause the operator to lose control of the boat or can even eject people from the boat. A boat with a flat bottom will porpoise more readily than a boat with a deep-V hull (i.e., a boat with higher "deadrise"), so low deadrise bass boats are more likely to porpoise than deep-V, ocean-going sport fishing boats. Generally, keeping a boat's forward speed below a critical value can reduce porpoising, and shifting the weight of the passengers and cargo forward can often prevent porpoising.
The skill and knowledge required to operate a high-performance boat safely is comparable to that required to operate an automobile safely, yet training for new boat operators is minimal compared to that for new car drivers. One high-performance boat manufacturer offers up to six hours of classroom and hands-on training, with a small fraction of that time actually spent on the water, and usually calm water at that. This manufacturer builds boats that go up to 120 MPH, comparable to driving a Ferrari on the Autobahn, yet their customers know more about how to open the motorized engine covers than how to approach large waves. Unfortunately, this manufacturer is one of the leaders in formal, hands-on training. Most boat-builders offer only a video that provides minimal training or just a printed owner’s manual.
Without an increased awareness of the requirements for operating high-performance boats, the number of accidents and deaths per passenger hour will continue to be unacceptably high.
On Line Boating Safety
You can take an online boating safety course at www.boatsafe.com. If you pass the final exam with a score of at least 80%, you can receive your Boating Safety I.D. Card and Certificate. Many insurance companies give marine insurance discounts to boat owners who have completed such a course.
Boat Propeller Strike Protection
By: Robert A. Warren, Ph.D.
A propeller strike is among the most gruesome of injuries. Rotating at hundreds and thousands of revolutions per minute, a boat propeller can crush, slice and gouge the human body, leaving disfigurement, amputation and death.
In the late 1970s, outboard motor manufacturers introduced an emergency stop switch as a feature of their product line. The “kill switch,” as it is commonly known, is tethered by a short lanyard to the boat operator and effectively shuts down the engine when the operator is thrown or moves away from the helm. Most outboard motors sold today contain this feature.Propeller guards or shrouds have been proposed for use on boats that move at displacement speeds (normally below 20 mph). At higher planing speeds, the current generation of propeller guards reduces propulsive efficiency and fuel economy, adversely impacts boat-handling quality, and substitutes blunt force trauma for cutting and gouging trauma. Outboard motor manufacturers provided propeller guards as options for slow-speed applications, but are concerned about resale that results in a high-speed misuse.
Within the past decade, boats driven by water jets have entered the market place. The jet boat, which does not use an exposed propeller, is new technology, and issues of cost, reliability, and handling quality exist.
A victim’s rights organization, Stop Propeller Injuries Now (S.P.I.N.), has done extensive lobbying of the Coast Guard and Boating Industry to create regulations associated with propeller strikes. It appears that S.P.I.N. has achieved an initial success for the Coast Guard, and is considering propeller strike regulations for rental houseboats.
Carbon Monoxide — The Silent Killer
By Bob Warren
Carbon Monoxide (CO) is called the silent killer. It is a colorless, odorless gas about the same density as air. CO is an exhaust product of internal combustion engines. The following is a tragic story from the annals of the boating world:
A couple decided to take a swim in a local lake. They got the family runabout, trailored it to the lake about midnight, and powered out with another couple. Everyone jumped into the water off the swim platform. The weather conditions late at night were calm, still and dank. The outboard motor on the open runabout was left operating at low idle. About 1:30 am, one couple got into the boat because they were tired. The young woman complained of a slight headache but associated it with drinking too much beer. At 2:00 am, the couple in the boat called out to the other couple that had remained in the water. They received no answer. The police and rescue squad were called to the scene. After a few hours, the bodies were found at the bottom of the lake. Police initially ruled the deaths a double drowning.
The parents of the deceased youngsters were convinced that they could not have drowned. An exhumation and autopsy were performed. The result was extraordinarily high levels of carbon monoxide in the blood. These youngsters had died of carbon monoxide intoxication while swimming too close behind the boat.
Testing revealed that in calm conditions, the carbon monoxide levels immediately behind the boat were over a thousand parts per million; quite sufficient to cause death in a short period of time. Even at five to ten feet away, CO levels were still high enough to cause illness and eventual death.
The symptoms of carbon monoxide intoxication mirror many maladies, a headache, some nausea, itchy or watery eyes, and more. These symptoms could be attributed to one beer too many, too much wind and sun, or even food poisoning. Too many boaters leave the engine idling while they are socializing in the water and playing near the back of the boat; particularly a boat with a swim platform. They assume that if the propeller is not turning or is guarded by boat structure, there is no danger. Unfortunately, carbon monoxide is a very real danger under calm weather conditions.
ATA Studies Houseboat Asphyxiation Danger
by Ed Fritsch
Each year in the United States, there are around 7 deaths and 30 serious, non-fatal poisonings from carbon monoxide (CO) aboard recreational boats. Long-term statistics from Lake Powell on the Arizona-Utah border illustrate the larger problem nationwide. Between 1990 and 2000, there were 111 separate CO poisonings reported on boats at Lake Powell. Seventy four of those incidents occurred on houseboats, and among those, 7 were fatal. To shed some light on this situation, ATA Associates recently completed a study that examined an asphyxiation hazard that is related to a common houseboat design feature, which resulted in a fatality at Lake Powell in 2002.
The subject boat in our study, like many houseboats, features a swim deck which cantilevers off the transom of the boat, over the rear out-drive propulsion units. This deck provides an attractive recreational space with ready access to the water for swimming and personal watercraft deployment while also providing protection from inadvertent contact with the houseboat’s propulsion system out-drives and propellers below it. Unfortunately, the swim deck also creates a confined space underneath it where propulsion system exhaust gases, including extremely high concentrations of CO, accumulate. In the accident that prompted the ATA study, a boater working to free an anchor rope fouled on one of the houseboat’s propellers, briefly ventured into the contaminated under-deck space and was immediately incapacitated by the high concentration of CO there. His incapacitation resulted in his subsequent death by drowning.
To understand the mechanics of the contamination process in the under-deck space and to test the effectiveness of various decontamination schemes, ATA constructed a detailed full scale mock-up of the under-deck volume. Carbon monoxide-laden exhaust was injected into the mock-up, and CO concentration was monitored electronically using instrumentation similar to that used by National Institute of Occupational Safety and Health (NIOSH) scientists in their tests of the accident boat conducted shortly after the fatal accident.
Monitoring the actual contamination process revealed that our first conceptual models of that process were oversimplified. Our initial conceptual models for a forced ventilation decontamination scheme for the under-deck space were also too simplistic. Ventilation tests with smoke from a theatrical smoke generator serving as a stand-in for CO allowed us to see a complicated mixing situation in the confined space that was relatively unaffected by our initial “scrubbing” strategy. Guided by such smoke tests, adjustments were made in the number, location and orientation of the ventilation blowers to significantly improve the efficiency of the decontamination process.
Ultimately, a practical ventilation scheme was developed and tested using real exhaust gas with initial CO concentrations as high as 80,000 parts per million. The final ventilator arrangement produced a rapid reduction of CO concentration to non-fatal levels in the under-deck space that would significantly reduce if not entirely eliminate the asphyxiation hazard which prompted the testing program.
ATA Conducts Boat Tests in Louisiana
by Ed Fritsch
Left and right: Cameras and electronics installed on boat; Inset: Top of trim tab shows adjustment range.In April and May of 2006, ATA Associates conducted a series of tests to determine the cause of a single-boat accident that occurred in 2003 on Louisiana's Lake Bisteneau. The boat involved was a late model, 17 ft. aluminum fishing boat powered by a 75 HP outboard motor. A passenger was seriously injured when he was ejected from the boat and was struck by the boat's propeller.
In its testing, ATA examined the steering performance of the subject boat involved in the accident. An almost identical exemplar vessel and motor were also tested. After a day of inspection and rigging with electronic test instrumentation, each boat was subjected to a full day of in-water performance testing on the Cypress Bayou Reservoir near Shreveport, Louisiana.
Items of particular interest were: 1) how the outboard motor's mounting location and orientation on the boat influenced its steering performance; and 2) how the motor's trim tab setting influenced steering. The influence of the motor's adjustable trim angle, relative to the transom, was also examined in tests which were conducted over each boat's full range of operating speeds.
The Louisiana tests were just the latest chapter in a long history of boat tests conducted by ATA Associates. With ATA's founder and owner, Robert Swint, at the helm, the subject boat in this case was put through its paces
in a series of tests that ranged from benign, low speed maneuvers to higher speed tests which culminated in anticipated, but nevertheless dramatic, losses of control. Though special care was taken to ensure Bob's safety in the latter tests, those tests were still not for the squeamish, nor for the boat operator who wished to stay dry.
While the drama of the loss-of-control tests was reminiscent of the early, glory days of boat testing by Bob Swint, upon which ATA was founded, the Louisiana tests as a whole represented the great strengths of today's ATA. The tests were monitored and recorded by video cameras on shore and by miniature video cameras mounted on-board the boat. In addition, during each test steering wheel input torque, steering wheel rotation angle, boat plane angle, motor trim angle and the forward, lateral and vertical accelerations of the boat at the passenger's seat location were all measured electronically and continuously logged at the rate of 500 samples per second. Boat position and speed, as determined by global positioning system (GPS) equipment, were also recorded, permitting a level of post-test performance analysis that would not have been dreamed of in ATA earliest days of boat testing.
Test results demonstrated and quantified the strong influence of the outboard motor's trim tab setting on boat steering performance. The lesser influences of trim angle and the improper mounting of the motor on the subject boat were also quantified. These observations led to the conclusion that an improper trim tab adjustment, and to a lesser extent an un-centered mounting of the motor, made the subject boat inherently unstable and dangerous if the steering wheel was released, even momentarily.
ABYC Announces Formation of New Committee
by Robert J. Swint
The American Boat & Yacht Council (ABYC) is a non-profit organization whose members have been developing and updating the safety standards for boat building and repair for more than 50 years. ABYC supports International Organization for Standardization (ISO) efforts and is a leader in basic education for the marine industry as well as in providing certification programs for marine technicians to improve quality and professionalism in the boating industry. ABYC's members include boat builders, boat owners, surveyors, boat yards, insurance companies, law firms, trade associations, marinas, dealerships, government agencies, educational institutions and equipment and accessory manufacturers. Volunteers donate time, expertise and labor while serving on technical committees which develop and revise ABYC standards and technical information reports.
Recently, ABYC has announced the formation of a new project technical committee called the Product Interface Committee. This committee is charged with examining the relationship and interactions between a boat as a whole, its on-board sub-systems, its operator and occupants, and its operating environment. Based upon the outcomes of its research efforts, the committee will determine if existing standards require updating or if entirely new standards are required to mitigate risks and the potential for injury or death. Areas of inquiry that the committee will pursue include engine cut off devices, falls overboard, propeller injuries, perception response times, and design of the operator's station. ATA Associates applauds the formation of the Product Interface Committee and looks forward to concrete actions by the committee to improve boating safety.
ATA was established in 1974 as an engineering consulting firm when its founder was asked to evaluate a boating accident in which a boat operator lost control of a stick-steering equipped boat, was ejected overboard and was ultimately struck and injured by the boat's propeller. The nature of the boat/operator interface in that accident, the dynamic behavior of that interface and the engineering shortcomings embodied in its design were all studied by ATA in that very early project. Now ABYC, through this new committee, has a means to begin to formally consider and address precisely those same kinds of topics and issues.
For over 30 years, ATA has been involved in the evaluation of scores of boating accidents where man-machine interface issues have contributed to the injuries or deaths of boat operators, occupants and passers-by. Over the years, ATA has focused considerable engineering expertise on understanding and quantifying the dynamic behavior of boats in various accident scenarios. While ATA has largely been successful in bringing to light a number of deficiencies in boat design, safety labeling and operator training, ATA welcomes the prospect of sincere actions by ABYC's new committee making significant new contributions to boating safety.
