Radio controlled engine kill switch

A engine kill switch system has a transmitter and receiver which are linked through specific transmitted codes within a frequency. The receiver is mounted directly on the boat and wired to an engine kill switch, maintaining the switch in the closed position as long as a signal is received from all of the activated transmitters. Once the transmitter signal is unintentionally deactivated, the receiver shuts down the engine. A range adjustment allows the separation distance between the transmitter and receiver to be changed, dependent upon the size of the boat and end use. A strobe and audio warning can also be attached to the receiver and activated simultaneously with, or as an alternative to, the deactivation of the engine. Automatic transmitter activation and deactivation can be provided through storage ports tied to the receiver. The transmitter is a battery powered remote device carried by a user. The transmitter has a programmed unique code recognized by the receiver. The system, or individual components, are provided with deactivation codes entered through an input device. The system can also be used as an antitheft device simply by removal of one transmitter, thereby rendering the engine inoperable.

This is a continuation-in-part of application Ser. No. 60/016,260 filed on 
Apr. 24, 1996. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
A radio controlled engine kill switch automatically shuts off an engine 
upon deactivation of a recognized individual code being continually sent 
by a remote transmitter. 
2. Brief Description of the Prior Art 
Boating is a popular, although dangerous, sport. Although there are 
frequent reports of boating accidents causing fatalities, many deaths are 
caused when people fall overboard and drown prior to being found in choppy 
water. Various safety devices have addressed this problem, however none 
have provided the combination of mobility and safety. 
In U.S. Pat. No. 4,483,683 a safety device design for use by a water skier 
is disclosed. The handle of the device contains a signal device which 
allows the skier to alert the boat and which also serves to indicate that 
the skier has fallen. The alarm is activated by a signal which is 
initiated by a conscious effort by the skier or as a "dead man's switch". 
The device, as taught by Alley, is applicable only to skiers and will not 
work for boat passengers. 
Hawthorne discloses in U.S. Pat. No. 4,785,291 a monitoring device which is 
used to alert a parent when a child wanders beyond a predetermined 
distance. The remote when in the predetermined distance causes the 
receiver to issue a slow "beep". Once the remote approaches the parameter, 
the beep becomes more frequent until, once the remote is beyond the 
parameter the beep becomes an alarm. This issue is addressed again in 
Narcisse's patent U.S. Pat. No. 4,593,273 wherein an Out-of-Range 
Personnel Monitor and Alarm is disclosed. Narcisse's device utilizes a 
receiver and remote system which activates an alarm when the remote is out 
of a predetermined range. Similarly Perez et al in U.S. Pat. No. 5,289,163 
discloses a Child Position Monitoring and Locating Device which activates 
an alarm on the receiver once the remote travels beyond the present 
distance. The device further includes a locating display which serves to 
locate the remote. Numerous other devices, have been disclosed which serve 
to indicate that a remote is beyond a predetermined range. The prior art 
devices, however, are for use in a controlled or uncontaminated areas and 
therefore are not provided with sufficient environment protection or range 
to be used as a boating safety device. 
The need for a warning device around water is recognized in U.S. Pat. No. 
5,274,359 issued to Adams. The transmitter of the '359 is attached to a 
child and allows for a directional indication of the location of the 
child. The transmitter is activated by water and commences sending an 
encoded signal to the receiver. The encoded signal also serves to assist 
in locating the child. 
An existing boat engine kill switch is a tethered device which must be 
manually attached to the operator of a powered boat and offers no direct 
safety factor for passengers. The tethered boat engine kill switch 
deactivates the ignition on the engine in the event the operator reaches 
the threshold of the tether. This severely limits the mobility of the 
operator, especially under working conditions. Because of this lack of 
mobility, the tethered engine kill switch is rarely used and places the 
operator, and needless to say the passengers, in a potential life 
threatening situation in the event of ejection from the craft. 
Although the danger around water has been recognized, none of the above 
prior art has addressed the issue of mobile water device safety pertaining 
to stopping the mobile device in the event of a passenger or driver 
overboard. 
SUMMARY OF THE INVENTION 
An engine kill switch system has a transmitter and receiver which are 
linked through specific transmitted codes within a frequency. The receiver 
is mounted directly on the boat and is directly wired into the existing 
engine kill switch wiring, thereby replacing, or supplementing, the 
existing kill switch. The receiver maintains the switch in the closed 
position as long as a signal is received from any of the activated 
transmitters. Once the transmitter signal is unintentionally deactivated, 
the receiver opens the kill switch and shuts down the engine. A range 
adjustment allows the separation distance between the transmitter and 
receiver to be changed, dependent upon the size of the boat and end use. A 
strobe and audio warning can also be attached to the receiver and 
activated simultaneously with, or as an alternative to, the deactivation 
of the engine. A locator device can be incorporated into the receiver to 
allow for easier location of a user possessing the deactivated 
transmitter. In one embodiment, storage ports can be provided on the 
receiver to hold the transmitters, thereby providing for automatic 
activation and deactivation. The transmitters can be either independent 
from the storage ports with any transmitter being deactivated by any 
storage port or specific transmitters being required for each storage 
port. An indicator light can be provided on the receiver to indicate which 
of the transmitters is no longer transmitting. 
The transmitter is a battery powered remote device carried by a user. The 
transmitter has a programmed unique code within the specified frequency 
which, once linked and activated, is recognized by the receiver. The 
transmitter uses batteries and includes an indicator light to indicate a 
low battery. 
The system, or individual components, are provided with over-ride codes 
which allow for deactivation. The override codes are entered through an 
input device and should be complex to avoid inadvertent shut down of the 
system. The system can also be used as an antitheft device simply by 
removal of one transmitter, thereby rendering the engine inoperable. 
The engine deactivation system has at least one portable transmitter, with 
an independent power source, such as rechargeable battery, which 
transmitting a constant individually identifiable signal. A receiver 
receives and recognizes the identifiable signal from each of the 
transmitters. Receipt of the signal by the receiver maintains the cut-off 
in a run mode and interruption of the constant signal from one of the 
transmitters activates the activation mode. Reinstatement of the 
transmission of the signal places the cut-off means in a run mode. An 
on-off device on both the receiver and transmitter can be provided to 
deactivate each unit. The receiver also has a cut-off which is connected 
to the engine and maintains a run mode and a deactivation mode, the 
deactivation mode deactivating the engine. A distance controller varies 
the transmission distance between the transmitter and the receiver. An 
antenna transmits the signal between the transmitter and receiver. Audio 
and visual alarms can be also included. An emergency cut-off device should 
be provided to break transmission of the signal and place the cut-off 
means in the deactivation mode, stopping the engine. A protection device 
preventing the emergency cut-off from being inadvertently activated. 
When the signal is blocked from the receiver the cut-off is placed into the 
deactivation mode, thereby cutting off power to the engine. The signal is 
blocked when the transmitter enters the water or is beyond the 
transmission range. An override allows the cut-off to be in said run mode 
without receiving a recognized signal. At least two indicator lights are 
provided which designate the power status of transmitter and said 
receiver, including the power level of the independent power supply within 
the transmitter. The indicator lights can be color coded to designate at 
least one of recharging, transmitting or low battery status check. 
The transmitter can be stored proximate the receiver when not in use with 
transmission of the signal beginning upon separation of the transmitter 
from the receiver. The transmission is stopped once the transmitter is 
returned to the receiver. 
The receiver can have a coding system which takes the individually 
identifiable signal from each of the transmitters and codes the receiver 
to recognize each signal. A data processor can receive data from both the 
receiver and transmitter, integrating the data into a database and 
displaying data.

DETAILED DESCRIPTION OF THE INVENTION 
The radio controlled engine kill switch system disclosed herein provides a 
safety and security device for use on boats, jet skis, and other water 
craft, as well as a security device for other motor run vehicles. The 
system maintains activation of the engine only while signals are received 
from all activated transmitters which have been partnered with the 
individual receiver. The transmitters disclosed herein are small and can 
be worn on the user's belt, wrist, around the neck or pinned to clothing. 
Although the transmitters can easily be incorporated into life jackets, 
statistics show that few people actually wear their life jackets, thereby 
eliminating the benefit of both the jacket and the transmitter. All of the 
equipment disclosed herein must be weather resistant and capable of 
withstanding salt water and the corrosion associated therewith. 
Activating the receiver by breaking the transmitter signal provides a 
critical safety measure. It is critical to turn off the engine as soon as 
the party enters the water. A unit which institutes the signal upon entry 
of into the water can fail to obtain the desired effect if the unit is 
defective. In the disclosed invention, if the unit fails, it fails on the 
side of safety by turning off the boat. 
A multi-user radio frequency controlled receiver 14 with multiple 
transmitters 12, is illustrated in FIG. 1. The radio transmitters 12, worn 
by the operator and each passenger, are coded to interact with the radio 
receiver 14 installed in the boat or other motor water craft. The RF 
contact between the transmitter 12 and receiver 14 must be maintained in 
order for the engine to continue to run. In the event the RF contact is 
broken, the engine is immediately shut down. Although a wide range of 
radio frequencies and their respective antenna types, may be applicable, a 
frequency with low tolerance to transmission through water can be 
advantageous in some applications. For simplicity in explanation herein, 
reference will be made to boat engines, however the instant invention can 
be utilized to deactivate other motor driven water devices, such as jet 
skis. 
The radio controlled engine kill switch system 10 allows the operator and 
the occupants the freedom to move about the craft while providing the 
safety and security benefits of an engine kill switch. Upon boarding 
nearly any sized power boat, the operator, and all or some designated 
number of passengers, would attach a small radio transmitter 12 to either 
their bodies or clothing. Each transmitter 12 transmits its own unique 
signal which, once activated, is recognized by the receiver 14 mounted 
within the craft. Activation of the RF signal can be through removal of 
the transmitter 12 from the receiver 14, an on-off switch, or other means 
obvious to those skilled in the art. The RF signal can also be continually 
sent and received, although the drain on the battery is extensive with 
this method. The receiver 14 is preferably range adjustable and would be 
set depending upon the size of the craft and the intended use. Therefore, 
if the passengers were to be fishing, the range would be substantially 
narrower than if the passengers were water skiing. When the radio 
transmission from any of the activated transmitters ceases, a switch 
within the receiver 14 immediately reverses, deactivating the ignition 
system on the boat engine. With approximately 75% of all boating 
fatalities being directly related to the operator or an occupant being 
ejected from their craft, the radio controlled engine kill switch 10 
becomes a potentially significant safety device in reducing boating 
fatalities. 
The radio transmitter 12 component of the engine kill switch 10 is a 
weather proof device which would be secured around the neck, wrist, arm, 
waist or ankle of the occupant of a powered boat. When activated, the 
transmitter 12 transmits a constant radio signal which is recognized by 
the receiver 14. Depending upon various factors, such as types of antennas 
used, the transmitter 12 uses a specific, individual code which falls 
within a specific frequency. 
In addition to the ability to deactivate the engine, the transmitter 12 
preferably contains several safety features. Replaceable lithium magnesium 
dioxide battery or a rechargeable battery such as a NiCad, are optimal to 
allow the transmitter 12 to recharge while not in use. A visible low 
battery indicator 16 should also be contained in the transmitter 12 for 
use with both rechargeable and non-rechargeable batteries. It is also 
preferable that the transmitters 12 be designed so that a low battery 
produces the same result as a dead battery. This will minimize the chances 
of a battery going dead during use. 
A manually operated "panic button" 18 installed in each transmitter 12 
allows any occupant wearing a transmitter 12 to discontinue their 
individual transmitter's 12 signal, consequently deactivating the motor. 
This feature is especially useful in the event a passenger who was not 
wearing a transmitter 12 was thrown overboard. It is also helpful in the 
event pets or cargo are thrown overboard or other emergency deactivation 
of the boat is required. Thus, any passenger wearing a transmitter 12 can 
deactivate the boat's ignition using the "panic button" 18 without needing 
to notify the operator of the boat to manually shut down the engine. The 
panic button 18 can have a cover to avoid inadvertent activation, however, 
access to the panic button 18 must be rapid and uncomplicated. A spring 
loaded, flip up cover would be an example of a simple to use, rapid 
access, cover. Further, in the event younger children are "on board", it 
would be desirable to have either child-proof locks on the transmitter 12 
or transmitters without panic buttons. 
As stated, each transmitter 12 has a uniquely coded signal with its own ID 
which is, in turn, recognized by the receiver 14. One of the ways this can 
be accomplished is by the use of an application specific integrated chip 
or a microprocessor controller. An example block diagram for both a 
receiver and transmitter is disclosed herein in FIGS. 8 and 9. Other 
methods of recognizing specific ID codes will be known by those versed in 
the art. By having a uniquely coded signal, each containing its own ID, a 
large number of transmitters can be operated on a common frequency. 
The radio controlled engine kill switch receiver 14 contains a switching 
device that replaces, or supplements, the engine kill switch on a powered 
boat. In the event the boat does not have an existing kill switch, the 
disclosed device can be directly wired into the engine electrical system 
as well known in the art. The receiver 14 is mounted directly on the boat, 
proximate the operator, and wired into the engine, replacing, or 
supplementing, any existing kill switch wiring. The switching device 
remains closed as long as the constant signals from all of the recognized, 
activated transmitters 12 are being received. In the event the receiver 14 
loses the activated signal of one of the transmitters 12, the switch 
opens, grounding or discontinuing power to the motor ignition system and 
killing the engine. 
As stated, the radio receiver 14 is preferably equipped with the ability to 
adjust the range of reception between the transmitter and the receiver. 
This can be through use of a variable sensitivity receiver controlled by a 
screw, knob or other device, as known in the art. The range adjustment is 
based on the size and use of the boat and would generally be done at the 
time of installation, with the control located inside the receiver 14. 
Alternatively, the control can be accessible and the adjustment 
accomplished by the operator of the boat through a range control 20. By 
providing the accessible range control 20, the operator is free to change 
the range dependent upon the current use. Thus, the range can be 
lengthened if the boat is being used for water skiing, or towing, and 
shortened for fishing or pleasure cruising. In the event the receiver 14 
is equipped with an accessible range control 20, a time activated default 
range is preferably built into the receiver 14. In this way, if the 
operator sets the range for water skiing and forgets to reset the range, 
the receiver 14 will automatically reset the range to the default setting 
after a predetermined period. The ability to adjust the range is necessary 
to allow for a single system to be used with most sized crafts. For 
example, one would desire the deactivation of the kill switch within the 
receiver 14, upon the loss of a transmitter 12 signal, to happen sooner on 
a twelve foot craft than on a sixty foot craft. If the receiving range is 
adjusted the same for both, an occupant overboard on a sixty foot craft 
would be separated by a greater distance from their craft than an occupant 
overboard in a twelve foot craft. Depending upon conditions, this could 
create a life threatening situation. For use with commercial, military or 
larger crafts, the receiver would be larger and more powerful to 
accommodate the vast size of the ship and the large number of 
transmitters. 
The electronic circuitry contained in the receiver provides the ability to 
search and recognize any codes within the specific frequency. At the time 
of manufacture, the receiver 14 is programmed with a specific frequency. 
In one method of recognization, the transmitters 12 are manufactured with 
each transmitting an individual code within this specific frequency. Only 
these individual codes are embedded within the receiver 14 as 
corresponding codes. The codes can be embedded into the receiver 14 in any 
number of methods known in the art. The receiver 14 coded in this manner 
has the ability to recognize only a certain number of codes within the 
frequency and the transmitters 12 must transmit only the pre-embedded 
codes. This is not a preferable method in that it limits the number of 
transmitters which can be recognized by each receiver and requires closer 
monitoring of the receiver production. Preferably, the receiver 14 has the 
capability of recognizing all codes within the frequency and only codes 
which are programmed into the receiver by transmitters will be active and 
recognized by the particular receiver. The programming can be "hard", such 
as switches, "soft", such as light, or other means known, which can 
transmit information from one source to another. There is an advantage to 
the receiver recognizing all codes and using soft programming, in that it 
allows the user to purchase additional transmitters, without concern for 
matching pre-embedded codes to the receiver, and add these transmitters 
without the expense of an installer. The receiver can be provided with a 
"program" mode in which it reads the information from the transmitter, 
thereby activating the code embedded within the receiver at the time of 
manufacture. Upon identifying the codes being transmitted, the receiver 
recognizes those codes as active transmitters. All activated transmitter 
codes are stored and loss of signal from any active code activates the 
engine kill switch. 
The receiver 14 is preferably powered by a rechargeable battery, such as 
nickel cadmium, nickel metal hydride or lithium. The recharging can be 
achieved by either voltage conversion from a generator, alternator, 
magneto, magnets, or the like or via photo electric cells. Since all 
powered boat engines do not have an external power source it is critical 
that the battery be the energy source powering the receiver. 
Within the scope of powered boat application, various types of antennas can 
be used with the receiver 14. The type of antenna being, in some 
instances, dependent upon the type and size of the boat. Examples of 
antennas which can be incorporated are omnidirectional, a rigid stick of 
an applicable size and length or a loop wire type encompassing the 
perimeter of the craft. For example, in a cruise ship application a loop 
antenna encompassing the entire ship may provide better coverage than an 
omnidirectional antenna due to the multi-deck construction. Frequencies 
will require coordinating with the type of antenna used, i.e. loop type 
antennas may require a lower radio frequency transmission than required by 
an omnidirectional antenna. 
As a further safety feature, a signal/warning strobe 22 is preferably 
mounted directly on the receiver 14 or, alternatively, on the body of the 
boat. The strobe 22 serves as a visual reminder and/or warning notice that 
the kill switch transmitter 12 has been activated. The system is 
programmable so that in very rough seas where a sudden interruption of 
power could endanger a boat, the system can be set to trigger only the 
visual and audible systems. Additionally while it would be obvious for 
occupants of the boat if the power was interrupted, the strobe serves to 
warn people boating or diving off the main craft that a problem has 
arisen. More importantly, however, the strobe 22 acts as a beacon to 
assist occupants thrown overboard to locate their craft at night. The 
strobe 22 receives power through a self-contained battery 24, rechargeable 
or standard, and becomes automatically activated by the deactivation of a 
transmitter 12 signal. A separate ignition switch can also be provided to 
manually activate the strobe 22 while the engine is running. The strobe 22 
can also be wired directly into the boat battery or other available power 
source. 
When the transmitted signal from any of the transmitters 12 is broken, the 
strobe 22 begins to flash simultaneous with, or as an alternative to the 
opening of the previously described engine kill switch. The strobe 22 
continues to flash until either the coded signal from the missing 
transmitter 12 is recognized by the receiver 14 or the strobe 22, and/or 
entire system 10 is deactivated. 
An audio warning 26 can be incorporated for further safety, serving as a 
notification for all on-board and off-board passengers. The audio warning 
26 is activated upon deactivation of the transmitter 12 signal. The audio 
warning 26 can be any pitch which can be heard over a distance and over 
the sound of the natural elements. By providing a pitch which will carry 
over the sounds of the ocean, the audio provides a second means to assist 
a person thrown overboard to locate the craft. It is also preferable that 
the audio warning 26 be intermittent to provide better locating 
capability. 
The strobe 22 and audio warning 26, as well as the engine kill switch 
system 10, can be manually deactivated, although it is recommended that 
the deactivation be somewhat complex. 
The radio controlled engine kill switch also serves as an antitheft device. 
As described herein the receiver will remain closed as long as all 
transmitter signals are being received. If the operator or an occupant of 
a powered boat were to voluntarily leave the craft, thereby leaving the 
predesignated field of the receiver, the switch within the receiver would 
open and render the boat engine inoperable. Since breaking the transmitter 
signal would activate the strobe and audio warning, manual deactivation is 
recommended prior to use as a antitheft device. 
When the transmitter component 12 is used as an antitheft device, and will 
therefore be separated from the receiver, the strobe 22 and audio warning 
26 should be manually deactivated until the transmitter signal was 
subsequently received. In the event a transmitter 12 is lost, stolen, or 
in some matter rendered inoperable, the operator may desire to deactivate 
the signal warning strobe 22 as a convenience. Deactivation in any case 
would become a conscious, manual decision by the operator. The signal 
warning strobe 22 deactivation is accomplished by entering a deactivation 
code into the receiver 14. This code would be a series of numbers, 
letters, symbols, light signals or the like entered via keypad, or other 
input devices 28. By successfully entering the warning strobe 22 
deactivation code, only the signal warning strobe 22 would be deactivated. 
The switch within the receiver 14 will remain open due to the loss of a 
transmitter signal and the engine would remain inoperable. An automatic 
reset for the deactivation of the signal warning strobe would take place 
when the receiver 14 recognizes the transmitter 12 signal upon the 
transmitter's return to the receiver's range. The audio warning 26 can 
also be provided with the capability to be deactivated in the same manner 
as the strobe 22 and is preferably deactivated simultaneous with the 
strobe 22. 
In the event the operator desires to override the entire radio controlled 
engine kill switch system 10, this would be accomplished in much the same 
manner as described in the deactivation of the signal warning strobe 22, 
using a more complicated code. This override procedure would close the 
engine kill switch allowing the engine to be operated without the kill 
switch. Deactivation of the engine kill switch would be a totally separate 
operation and should not render the signal warning strobe inoperable. 
Optimally, for safety, overriding the kill switch system would activate 
the signal warning strobe 22. Once the entire system is deactivated, 
deactivation of the signal warning strobe 22 would constitute a separate 
action and be accomplished using the prior described action. As a further 
safety feature, a "confirmation code" can be required if the engine kill 
switch system 10 and strobe 22 are deactivated within a certain time 
period from one another. 
In the event a transmitter is lost, broken or otherwise rendered 
inoperable, the system must be notified that the transmission will no 
longer be received. This can be accomplished in several ways, the easiest 
of which is to manually turn off the engine and restart, thereby rebooting 
the system. This is only applicable to systems where the transmitters are 
not in physical contact with the receiver and are manually activated. In 
systems where the transmitters are tied to storage ports, the system must 
be notified and ordered to accept the transmission loss. This can be 
accomplished through preset entry codes through the input device. 
Alternatively, a "dummy" transmitter can be included with each system 
which transmits a code unilaterally accepted by all receivers and allows 
for the temporary reactivation of the engine. 
While in its simplest form a system is comprised of a single transmitter 
for the operator, as disclosed heretofore, the technology allows for a 
substantial number of transmitters to be used with a single receiver. The 
storage, activation and deactivation of the transmitters will vary 
dependent upon the size of the application, cost of manufacture and 
preferences of the end user. In the specific instance of a moderate craft 
system with approximately ten transmitters, the transmitters can be stored 
directly into the body of the receiver 14, as illustrated in FIGS. 1 and 
2. Upon inserting the transmitter 12 into a storage port on the receiver 
14 deactivation of the transmitted signal would occur. The transmitter 12 
can be linked to the storage ports in either of two methods. In the first 
method, each storage port can be linked to a specific transmitter 12, 
requiring that the transmitter 12 must be placed on its respective storage 
port in order to deactivate the signal. This provides the advantage that 
the names of the users can be placed above the storage port and a 
transmitter 12 identified with a specific user. Indicator lights 30 can be 
used to indicate which of the transmitters 12 has activated the kill 
switch system 10. Alternatively, any transmitter 12 can be placed on any 
storage port, thereby deactivating the signal. Although this does not 
provide for the safety feature of knowing the identity of the party 
carrying each transmitter 12, it does make activation and deactivation 
simpler. The advantages of each system would be dependent upon the end 
use. The storage ports can contain a magnetic sensitive reed switch 56, or 
other means known in the art. When any transmitter is removed from the 
storage port, the transmitter signal would be automatically activated and 
recognized by the receiver 14 as an active transmitter 12. 
FIG. 2 illustrates an alternate design and incorporates a locating device 
58 within the kill switch system 50. The locating device 58, is 
incorporated in the receiver 52, and can be automatically activated upon 
deactivation of the transmitter 51 signal. The locating device 58 uses 
standard locating technology which preferably has been wired to become 
activated when the transmitter 54 signal is broken. By the nature of this 
device it becomes a locator for the person, or persons, that have broken 
transmission contact with the receiver 52. A simple directional antenna, 
tuned to the frequency of the transmitter 54 being worn by the lost party, 
can easily locate that party. For example, in the event the operator 
wearing a transmitter 54 was separated in violent seas from the craft, the 
engine kill switch would immediately shut down the engine and/or activate 
the visual and audible warning systems depending on programming. If the 
engine was deactivated, due to drift, wind, fog or other conditions, the 
separated party may be unable to be reunited with the craft. A search 
party, using a directional antenna, would be able to locate the 
transmission signal and consequently the lost party. The use of a single 
frequency provides an advantage by narrowing the scope of the search to 
the used frequency. Additionally, a single, consistent frequency makes it 
easier for other parties, such as the coast guard or Global Positioning 
Systems, to monitor for lost boaters. In the example of a cruise ship, it 
is entirely possible that a child left at port could be located with a 
directional antenna. Global positioning systems are decreasing in size, as 
well as becoming more financially affordable and can be easily 
incorporated within the disclosed system. 
In the case where this technology were to be adapted to a large number of 
passengers such as a cruise ship, ferry, military or equivalent 
multi-passenger craft, this device would allow the operator to keep track 
of all or a specific group of passengers. If, for example, a cruise ship 
operator were to want to keep track of all children under the age of 
twelve, the operator may require the attachment of a small transmitter to 
the wrist of those occupants. 
When larger numbers of transmitters are involved, as illustrated in FIG. 3, 
the transmitters 104 can be stored on a holding bar 102 wired to the 
receiver 108. The holding bar 102 can be proximate the receiver 108 or in 
an accessible location a distance from the receiver 108. The receiver 108 
can be provided with a viewer 110, such as a LED, which will display the 
code of any transmitter 104 which has broken its signal with the receiver 
108. On large ships, such as cruise or navy craft, the name of the person 
using each transmitter can be logged into the receiver 108 or tied into 
the ship's computer, representing a significant safety factor in the event 
a child fell overboard or was accidentally left at a port stop. In the 
event a transmission is broken, not only would the usual alarms be 
activated, but the identification of the person would be known. The loss 
of a transmitter signal would give an audible and/or visual signal in the 
control room and allow for appropriate action to be taken. The operator 
would know immediately, through the computer, all pertinent information 
concerning the wearer of the disconnected transmitter and expediting 
location of the user. This type of system would also possibly reduce the 
liability to the operator. This can also be helpful if it is known in 
advance that the person will not be in range and that the transmission 
will be broken, allowing the system 100 to be reset. Alternatively, the 
receiver 108 can be provided with the capabilities to override the alarm 
for any one transmitter 104 for a set period of time, reactivating at the 
expiration of the set period. This system can be advantageous with scuba 
divers wherein the transmitter 104 can be overridden for the period of 
time slightly less than the air supply in the tanks. 
FIG. 4 illustrates an alternate engine kill switch system 200 wherein the 
receiver 202 and the transmitters 204 are not in physical contact during 
storage. Therefore the initial activation and subsequent deactivation must 
be through means other than removal of the transmitter 204 from the 
receiver 202. The transmitters 204 are picked up from the storage location 
and activated either at the storage location or taken to the receiver 202 
for activation. Preferably, each transmitter 204 has its own activation 
light 206 on the receiver 202 to indicate that the transmitter 204 has 
been activated. Activation of the transmitters 204 can be through numerous 
methods, such as bar codes or magnetic readers. The emergency cut-off, or 
panic button, can also be used to activate the transmitter, although the 
method of activation must be completely different from the operation of 
the panic button. For example, the panic button would be pulled out and 
twisted to initiate transmitter activation. In instances where the users 
are consistent for long periods, such as a naval vessel, the transmitters 
204 can be tied to a particular person upon each activation. This can be 
done through manual entry upon the time of activation or in combination 
with other identification methods which are currently being used in the 
particular application. In this embodiment, the indicator lights 206 can 
be a LED type, thereby providing a name, or other personal identification, 
upon activation of the transmitter 204. 
A single user unit 300 is illustrated in FIG. 5 with the transmitter 308 
attached to the receiver 302 for storage and/or recharging. In the 
embodiment illustrated, the front plate 318 has a larger perimeter than 
the round insert 304. The use of this configuration allows an easy-to-cut 
hole to be drilled into the mounting area, electrical connections made, 
and the unit 300 secured through use of screws or other means known in the 
art. Once mounted the front plate 318 covers the hole cut to receive the 
insert 304, providing a quick and easy installation. It should be noted, 
however, that the illustrated configuration is an example and other 
configurations can be used for both the front plate and insert. 
As stated heretofore, the transmitter 308 continually sends the specific 
code to the receiver 302 until the signal is broken, as for example by 
distance or water. Although the distance between a boat and user would not 
be as critical prior to the signal being broken, in an overboard situation 
immediate reaction is required. For this reason, a water sensor 312 is 
used to immediately break the signal and initiate the engine shut down. As 
can be seen in the flow chart of FIG. 7, once water is detected by the 
water sensor 312, the transmitter 308 is turned off, and waits in an idle 
mode until the transmitter 308 is taken out of the water. Various methods 
can be used to reactivate the transmitter 308 once it is removed from the 
water, including adding a reactivation switch, including the reactivation 
in the circuitry, requiring reattachment to the receiver 302, or in the 
simplest form simply removal from the water. These, and other methods, 
will be apparent to those skilled in the art. 
The attachment method of the transmitter 308 can be through use of any of 
several methods, or combinations thereof, known in the art, such as 
magnets, snap-on clips or a bottom indent. Due to the corrosive nature of 
salt water, it is preferable that the attachment method be easy to 
maintain. The transmitter 308 operates on batteries which are placed in 
the battery receiving area 320. As stated, the batteries are preferably 
rechargeable and are recharged directly from the receiver 302 in any of 
the various manners known in the art. The battery receiving area 320 is 
protected from the elements by closure cap 314. The closure cap 314 also 
allows for access to the code set panel 322 which contains any of the 
switches necessary to synchronize the signal with the receiver 302 or make 
any other manual circuitry changes necessary based on the electronics 
utilized. 
Both the receiver 302 and the transmitter 308 preferably contain visual or 
audio means to determine their current status. As an example the 
illustrated unit 300, both the receiver 302 and transmitter 308 contain 
lights 306 and 310 respectively. In the example used in FIGS. 5-9, the 
lights 306 and 310 are both green when the transmitter 308 is attached to 
the receiver 302 to indicate that the transmitter 308 is charging. Once 
the transmitter 308 is removed from the receiver 302, the lights 306 and 
310 turn red to verify that the link between the transmitter 308 and 
receiver 302 is in existence. The aforenoted low battery indicator can 
also be incorporated into the transmitter light 310 using a flashing mode 
to indicate the need to recharge. The transmitter's 308 low battery status 
can also be indicated on the receiver light 306 and would be activated by 
a weak signal. An audio signal can also be incorporated in the 
transmitter, similar to those used in pagers, to indicate a low battery. 
The receiver 302 is armed or disarmed through use of a key switch 316. This 
also allows the system to be reset when needed. The key switch 316 can be 
provided with positions to arm, reset or disarm the system, thereby 
providing more alternatives for the user than simple on/off modes. 
FIGS. 6 and 7 provide example control flowcharts for the receiver 302 and 
transmitter 308 of FIG. 5. The block diagrams of the example transmitter 
and receiver are illustrated in FIGS. 8 and 9. As can be seen from FIG. 6, 
once activated the receiver continually verifies that a code is being 
received, checking the code against the known address of the "partnered" 
transmitter. If the received code address matches the known code address, 
the receiver proceeds to cycle through the process. If, however, the code 
is not received, or an incorrect address is received, the system disables 
the motor. Various checks and balances, examples of which are illustrated 
in the flow chart 600, should be incorporated to prevent false shut downs. 
The transmitter 308, as charted in flow chart 610 continues in a stand-by 
mode until detached from the receiver. Once the transmitter is detached 
from the receiver, the transmitter circuitry adds the transmission loop, 
continually checking for the presence of water. If water is not detected, 
the system continues to loop. When water is detected, the system turns off 
the transmitter and enters a sub-loop continually checking for the 
presence of water. Once the transmitter is out of the water, the main loop 
is re-entered and the system proceeds transmitting. The basic elements of 
the receiver and transmitter are illustrated in the block diagrams 620 and 
640. 
The activation of the transmitter at the time of use can be incorporated 
with any of the foregoing embodiments. In the embodiments wherein the 
transmitter is activated by means other than removal from the receiver, a 
shut down mode must be provided. This can be accomplished through manual 
entry, repeating the initial activation step, turning off the engine or a 
combination thereof. Optionally more than one action can be required to 
shut down the transmitters in order to prevent inadvertent transmitter 
shut down. Additionally, any of the described features, such as audio 
alarm, locator, etc., can be utilized with any embodiment, whether or not 
it was described or shown in conjunction with the embodiment. 
As stated heretofore, there are instances when automatically shutting down 
the engine can place the craft in danger of being capsized. As an 
alternative to manually switching from engine shut down to visual/audible 
systems, the engine kill switch can be used in conjunction with 
computerized sensing devices. The sending devices should track both the 
degree pitch and duration of time the craft has been pitching. Thus, in 
the event a signal is broken, the system checks the sensing device. If the 
pitch is greater than a preset standard and has been continuing for 
greater than the preset period of time, the system makes the determination 
not to shut off the engine. By checking both the duration of the pitching, 
as well as the degree, boat wakes and other short term disturbances, will 
not eliminate the deactivation of the engine. 
The disclosed system can also be modified to serve as antitheft for rental 
boats, water skis, and other engine powered vehicles. The vehicles would 
be equipped with a small, single transmitter receiver. The transmitter 
would operate as described heretofore, with the addition of a programmable 
time and signal chip. The transmitters would be programmed to transmit a 
code to the receiver for a predetermined amount of time, for example one 
and a half hours in the event of an one hour rental. After the 
predetermined time has run out, the code would cease transmitting, 
therefore deactivating the engine. A location code would subsequently 
commence transmission, allowing the owner of the vehicle to locate the 
missing vehicle. For safety reasons, it is recommended that a warning 
signal be emitted from the receiver and/or transmitter indicating that the 
vehicle must be returned. A countdown timer can also be incorporated in 
the receiver, indicating the time remaining on the rental. 
Since other modifications and changes varied to fit particular operating 
requirements and environments will be apparent to those skilled in the 
art, the invention is not considered limited to the example chosen for the 
purposes of disclosure, and covers all changes and modifications which do 
not constitute departures from the true spirit and scope of this 
invention.