Propellor Torque And Single Point Failures in Boat Steering
On any boat powered by a single outboard motor, the spinning propeller not only drives the boat forward, it also generates a torque on the motor which will turn both the motor and the boat if that torque is not restrained somehow. A propeller rotating clockwise, which is typical for most propellers, generates an inherent, propeller-induced "steering" torque that will turn a boat to the right as it moves forward, if that steering torque is given free rein.
With simple, tiller steering, the propeller-induced steering torque on the motor can be felt by the boat's operator as
force acting through the motor's tiller handle. That force must be resisted if the boat is to be successfully controlled by the operator. Likewise, with most single-cable steering systems, the operator can usually feel the steering force acting through the steering wheel via its cable connection to the motor. Even if he can't feel the force, if the operator releases his grip on the steering wheel, he will see the force at work in spontaneous turns of both the wheel and the boat. On the other hand, the propeller-induced force usually can't be felt through the steering wheel of most hydraulic steering systems, and, if the steering wheel is released, there will be no spontaneous turn of the wheel or the boat. This is because the reciprocating action of a piston pump in the helm of most hydraulic systems typically isolates the rotary motion of the steering wheel from the linear motion of the hydraulic cylinder acting on the motor's tiller lever. This arrangement does not eliminate the propeller-induced steering force, however. It merely puts a check on that force which persists in the form of unbalanced port and starboard pressures in the hydraulic steering system and which will be ready to act on the boat whenever it has the opportunity.
Like all mechanical assemblies, boat steering systems are subject to various malfunctions. If such malfunctions permit the propeller-induced steering torque to turn the boat abruptly, they can have disastrous consequences. A boat's operator and passengers can be ejected from a boat if the boat undergoes a sudden, unexpected turn while under way, and the probability of such ejections increases with increasing boat speed.
Commonly seen malfunctions in cable steering systems occur in the telescoping rod and tube assembly which passes through motor tilt tube at the boat's transom and then connects to the motor's tiller lever. Corrosion of a cable-to-rod coupling inside the assembly can result in complete binding of the steering system if corrosion products swell the outside diameter of the connector too much. That situation is typically discovered after a boat has been out of service for a long while, and it usually prevents the boat from being used again until the whole cable assembly has been replaced. A more dangerous situation occurs when erosive corrosion of the connector weakens it to the point of failing in service, allowing the steering cable to completely separate from rod and tube attached to the motor's tiller lever. In that circumstance, an abrupt boat turn and the ejection of operator and/or passenger(s) are likely to occur. The investigation and diagnosis of each of these malfunctions can typically be accomplished only by way of industrial radiography or destructive disassembly, since cable steering systems are usually factory-assembled by irreversible means.
Hydraulic steering systems are also subject to malfunctions which can result in abrupt boat turns. Given that, in normal operation, a hydraulic steering system typically conceals the presence of the propeller-induced steering force, abrupt turns related to hydraulic system malfunctions can be, in some sense, more unexpected and so, more hazardous than turns related to cable system failures. Hydraulic system failure modes include catastrophic breaches of hydraulic fluid pressure due to abrasive chafing of flexible tubing against rigid boat structures or the sudden release of pressure through improperly assembled tubing-to-fitting connections. Another failure mode originates in the design of one low-cost hydraulic steering system which uses non-redundant threaded fasteners at the ends of an assembly which confines the lateral movement of the actuating cylinder attached to the motor's tiller lever. In-service loosening and loss of one or both of those fasteners can result in loss of steering system control over the motor and an abrupt boat turn even though the fluid pressure retaining envelope of the steering system remains intact and leak free.
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Hydraulic Steering System Connection Testing
In an investigation of a boat operator's ejection in an incident where a hydraulic steering system failure occurred, ATA pressure tested connections in an exemplar steering system. If properly assembled, the pressure carrying capabilities of tubing-to-fitting connections exceeded the bursting strength of the plastic tubing. If not properly assembled and tightened, connections were seen to fail abruptly by slipping at pressures well below the tubing burst pressure, without any prior warning such as a tell-tale leak.
ATA Associates has been investigating boating accidents for decades. From collisions and prop injuries, ATA experts have analyzed hundreds of scenarios related to boating safety including:Boat Dynamics
As technology has improved, so has the ability to collect real time data that helps investigators re-create accidents and evaluate testimony relating to an accident. Newer commercial GPS units installed on recreational vessels now automatically keep a running record of where the vessel has been. This information has become very detailed to include factors such as time, heading, and speed. This data can be extracted and analyzed to provide solid evidence in a case. More advanced GPS units collect 10 samples per second, helping to accurately describe characteristics during testing. Other instruments such as load sensors and solid state rate gyros combine to create a full data package that explains important details of the vessel performance. Testing with these instruments gives investigators knowledge of acceleration, pitch and roll rates and forces exerted on occupants. The information is saved on data collecting software and analyzed to show multiple aspects of the vessel’s behavior.
Testing has become a crucial part of the reconstruction process. Using exemplar vessels and modern measurement technology, investigators can collect data that was not available previously. When possible, a test protocol should be based on witness statements and physical evidence. In the planning process, decisions are made as to what types and quantities of data are going to be collected.
Location and installation of devices needs to be planned and video documentation needs to be addressed. All these considerations are a must for successful testing.
Collecting and interpreting the data is just one step into reconstructing a boating accident. All this data is useless unless it can be comprehensively explained and professionally presented. At ATA Associates, the latest in computer graphics are used to show how vessels performed during testing. Technical data is transferred to graphics programs and presented in a clear and concise manner. Three-dimensional animations are created to inform and educate viewers. These animations are based on the collected technical data and can show details that charts and graphs cannot.
The Overall Package
The vast knowledge and experience provided by the ATA team of professionals can be instrumental in achieving a positive outcome. Conclusions based on carefully planned and executed testing, establish credibility for the expert’s testimony. Creating clear documentation and exhibits emphasizes the results Successful boating accident reconstruction takes experience and expertise like that found at ATA Associates.
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.
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.
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).
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
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.
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
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
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.
Line Boating Safety
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.
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.
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.
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
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
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:
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
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.
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
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.
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.
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.
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.
ATA Works with GPS Technology in Reconstruction of Boating Accident
ATA Associates provided accident reconstruction services to Lewis, Kullman, Sterbcow & Abramson in a lawsuit on behalf of a former offshore vessel industry manager who was killed in a 2013 collision between his recreational boat and a commercial workboat in a narrow waterway in the Mississippi River delta, about 75 miles southeast of New Orleans. ATA's reconstruction of the head-on collision supported claims for compensatory and punitive damages by the decedent's widow and two minor children which were recently resolved in a confidential settlement agreement. Knowledge of a variety of technical disciplines was required to make sense of the facts of the case, and several of ATA's staff members collaborated on the challenging but successful effort.
Global positioning system (GPS) data were available from the plaintiff's boat, but not from the workboat involved in the collision. The GPS data established the speed and the path of the plaintiff's boat, beginning well before the collision and ending at that boat's final rest position. The moment in time and, therefore, the particular location of impact between the two craft were determined from a 'spike ' found in the deceleration history of the plaintiff's boat, which was derived from the GPS time and distance data for that boat. An accurate reconstruction of the specific location of the collision was needed to address 'around the bend' line-of-sight issues for both boats related to curvature of the channel in which the collision occurred.
In the absence of GPS data for the speed and direction of travel of the workboat, those features were determined by other means. Matching and aligning linear scrapes on the top surfaces of the plaintiff's boat with complementary marks on the underside of the workboat's hull (both sets of marks having been observed and documented during ATA's physical inspection of both vessels) not only showed that the mishap had been a dramatic override of the workboat over the recreational craft, but also clearly established the orientation of the two vessels at the moment of initial contact. The override collision indicated by the marks analysis was also consistent with the nature and severity of the injuries sustained by the occupants on the plaintiff's boat. The speed of the workboat at the moment of impact with the plaintiff's boat and its change in speed through the ensuing over-ride were then calculated using momentum exchange and conservation of energy as guiding analytical principles.
In sum, ATA's reconstruction established that the workboat was on the wrong side of the channel at the time of the collision; having "cut the corner" of the curve in the channel where the mishap occurred. Additionally, ATA's reconstruction indicated that the workboat was travelling at an imprudently high speed, so that when it encountered the on-coming recreational boat the ensuing collision could not be avoided by either boat operator.
Boating represents one of the world's oldest forms of transportation and vessels of many types stand as the cornerstone to world commerce, seafood harvest, aquatic industry and recreational marine travel. Similar to other forms of transportation, most shipping and smaller vessel designs that are produced in this modern era place an ever increasing focus on safety. But, what about inland waterway boating and small vessels used in the recreational and non-passenger vessel classification of marine activity?
Without a doubt, the passage of the U.S. Coast Guard Boating Safety Act of 1971 has resulted in the saving of countless human lives through the establishment of manufacturer compliance guidelines for electrical systems, fuel systems, ventilation, safe loading (capacity) and flotation requirements for recreational boats. In concert with these federal manufacturing safety regulations, the life jacket (PFD) industry has developed hybrid and inflatable floatation devices that more appropriately fit the small vessel environment and are comfortable to wear. The National Marine Manufacturers are producing more efficient hull designs that possess more durable and user-friendly components while state governments, the US Power Squadrons and the Coast Guard Auxiliary are hosting thousands of boating safety educational classes each year that are producing a more knowledgeable class of boaters.
Statistically, the risk involved in recreational and small vessel operation on state waters has essentially remained flat lined over the last ten years when accounting for the number of people killed in these type of vessels. Although it is true that without the new regulations, educational efforts and industry technological advances, the number of fatalities would be much higher. There is still much to be done. In particular small open vessels, those less than 26 feet in length, have not kept pace with the general risk reduction technology that larger vessels have enjoyed. Collision avoidance/warning, passenger/occupant seating safety, and occupant ejection prevention represent several potential technology advances which could greatly reduce boating accidents.
Future mitigation strategies to help reduce injuries and deaths on small boats might include the development of a safety envelope within the small vessel that considers adequate operator and passenger seating which does not impair visibility from the helm and minimizes the risk of ejection in collisions/allisions. Such a safety envelope should consider adequate and safe seating in relation to a vessel's actual persons capacity and not just recommended seating locations for a lesser number of occupants than the actual rating. The design of the seating should consider all the dynamic forces which can be applied to an occupant aboard a small vessel with special emphasis on side and forward ejection trajectories and onboard trauma impact points.
Over the last 50 years small boats and the operators who control them have endured many new regulation based safety requirements. Most of these regulations are focused toward accident prevention. We believe that it is time to consider technology that addresses the severity/survivability of accidents as well as preventative measures that serve to reduce accidents and their consequences. Regulations and education alone will never totally prevent boating accidents, as history has illustrated with land-based transportation. However, the lessons learned from these industries would point the small vessel industry toward technology that prevents and/or reduces deaths and serious injuries incurred in spite of accidents.
The downloading of stored data from digital systems on cars and trucks is a routine part of the investigation and reconstruction of nearly every traffic accident. Though the systems which record those data were developed by vehicle manufacturers only to control and monitor on-board systems for improved vehicle performance and maintenance, the data have now become widely regarded as indispensable tools for accident reconstruction.
As with motor vehicles, the relentless march of digital technology has brought computerized control and monitoring systems to the engines of recreational boats, though such systems are less pervasive in boats than in cars and trucks. There is, as yet, no boat monitoring system that is as “crash dedicated” as the airbag control module in a car or the hard stop monitor in the engine control module (ECM) of a commercial truck.
The introduction of electronic fuel injection by Mercury in the 1980s opened the door for relatively simple digital monitoring and control of outboard motors. Since then, the complexity and reach of electronic engine controls have significantly expanded, making it possible to collect and store much more outboard motor performance information. Mercury, Suzuki and Yamaha all employ sophisticated engine controllers which monitor performance parameters such as fuel pressure, water pressure, the function of fuel injectors and battery charging voltage and current. Generally, the newer the motor, the more data is being monitored.
The data stored by a late model outboard motor, and available for download by connecting a laptop computer to the motor’s diagnostic port, are typically of two types – fault code logs and run time histories. Typically, when downloaded, these data are presented in plain English with no special skill or training required for their interpretation.
Newer outboards record every instance when the motor generates a fault code. These would include overheating, over revving of the motor and over charging of the battery. Additional data may also be recorded. In the case of an overheat, the log may include the date it happened and the duration of the overheat event.
A run time history will indicate the cumulative total of hours of operation. Mercury, Yamaha and Suzuki also provide a histogram or statistical break down the hours in 1000 rpm increments, from idle to 6000 rpm, depending on the motor's range. These data may provide insight into possible irregularities in the way the motor was operated over its lifetime.