International VentureCraft Corp.
Tel: 604 436 5653
SportSub
Technologies
Today’s SportSub family of personal submersibles
is the culmination of over twenty years of product
refinement. Just peruse the numerous technologies listed
below and you will begin to appreciate the lengths to
which International VentureCraft Corp. will go to provide
the safest, most reliable, attractive, easy to use, and
exhilarating submersibles available anywhere. The design
is both sophisticated and elegant in its simplicity. If
that sounds like a paradox - read on and you’ll
understand.
A casual inspection of a SportSub makes it look
deceptively simple. It’s very attractive but doesn’t
look very complicated or high-tech. Looking up from
below, the hull appears to be nothing more than an open
shell. What keeps water out of the cockpit? Why is there
a big hollow nose with an open bottom? This sub must be
just a capsule that SCUBA divers use to drive around
while wearing their breathing apparatus! Why not just use
a dive puller?
It’s because of misconceptions like these that we
proudly present the worlds most sophisticated and
practical submersible technology for recreational,
commercial and shallow industrial operations.
Concept
For a more detailed explanation of the many advantages
of an ambient pressure submersible over other sub
technologies see our document called Ambient
Advantages.
The basic principle of the ambient pressure
submersible is the same as a diving bell. It’s like
taking a giant drinking cup and turning it upside down
and pushing it under water. The air trapped inside stays
there as long as you don’t tip it too far sideways.
The bottom is open to the water so the internal pressure
and the external pressure are always equal. The SportSub
design ensures that the air pocket trapped in its cockpit
never shrinks or expands as pressure changes during
descends or ascends. If the air pocket volume were
allowed to shrink or expand with changing pressure the
buoyancy would change, causing a loss of control. This is
regulated by the SportSub’s automatic buoyancy
control system, which maintains neutral buoyancy
throughout a dive.
Stability
Neutral buoyancy does not equal neutral stability
however. The SportSub is kept in a stable, upright
position at all times because its center of buoyancy and
center of gravity are as far apart as possible, causing a
sort of pendulum effect. The bottom of the SportSub is
where the majority of its weight is located and the top
is where the buoyant air pocket is located. This causes a
very strong tendency for the bottom of the sub to stay
directly under the top, and prevents any air from
spilling out the bottom of the cockpit.
Buoyancy Range
SportSubs can be configured to ride high on the
surface, with the entire cockpit and upper hull above
water, submerged at neutral buoyancy, or landed solidly
on the bottom with enough weight to keep them there while
the occupants exit for an extra-vehicular excursion. All
of this can be accomplished with a range of combined
passenger weights up to 600 pounds in the three-seat
models.
Buoyancy adjustment is accomplished by flooding or
blowing water ballast within three separate ballast tanks.
Flood valves in the cockpit allow air to escape out the
tops of each ballast tank while water floods in through
their open bottoms. Blowing ballast reverses this
procedure, requiring the flood valves to be closed while
blow valves are opened to allow pressurized air to bubble
into the tanks, rising to the top and forcing water out
the open bottom. The forward ballast tank is the hollow,
bottomless nose. The entire tail section, surrounding the
main air supply tanks, is the aft ballast tank, and the
cockpit itself is the third tank.
To ride high on the surface all three tanks are filled
to capacity with air. To submerge, both fore and aft
ballast tanks are completely flooded while the air volume
in the cockpit is adjusted such that neutral buoyancy is
achieved at the occupant’s weight. To land on the
bottom, the cockpit air volume is adjusted to its
minimum, providing maximum negative buoyancy.
Entry/Exit
It might be nice for a SportSub to have an entry and
exit hatch at its highest point so passengers could climb
in and out above the water. There are several advantages,
however, to the swim-in method we chose.
The greatest advantage is safety. The simple rear
opening can never get stuck or jammed shut, trapping
occupants inside. It is also immune to leaking. If a
hatch at the top of the cockpit were to leak, all the air
would escape and buoyancy would be lost. A third safety
feature of the swimming entry is to ensure that occupants
are not prone to panic. Having to
enter the sub by swimming into the cockpit is a nice way
to help prevent passengers from taking a ride if they
aren’t comfortable under water. This gives the
operator some confidence that passengers will be capable
of handling a 'worst case' emergency situation.
Another benefit of the open hatch approach is cost.
Our solution is free! A good quality sealed submarine
hatch could easily cost as much as an entire SportSub.
Visibility
It seems logical to assume that more windows would
provide better visibility. This is not the case under
water, for two reasons; reflection, and refraction.
Most underwater environments are dimly lit as light
filters down from the surface. This surface light must be
kept out of the cockpit or it will cause reflections. It
would be somewhat like driving a car at night with the
interior light on. Anything bright in the cockpit would
be reflected by the front windows, causing a ghost image
to appear in the pilot’s field of view.
The SportSub’s balanced pressure hull allows
large, flat windows to be used because they don’t
have to withstand much pressure difference. Flat windows
minimize the natural distortion, called refraction, which
occurs when water and air meet. These are used for
forward-looking windows to permit accurate visual
navigation. The dome shaped side windows exploit the
distortion effect and provide a wide-angle lens effect
allowing occupants to see a larger vista.
Breathing Air Quality
Fresh air is continually circulated through the
cockpit during a dive. Airflow is regulated by a flow
meter which is set by the pilot according to a formula,
depending on how many occupants are in the SportSub. This
formula was developed through extensive research done by
scientists and medical doctors using a SportSub cockpit
in a hyperbaric chamber. All breathing gasses were
monitored while different sized subjects occupied the
cockpit in the chamber. Male and female subjects were
tested, both at rest and under conditions of controlled
exertion. The chamber was set to various pressures to
simulate different depths. The formula was derived to
provide adequate airflow for worst-case conditions.
During normal operation of a SportSub there is much more
air circulation through the cockpit for buoyancy control
than from the flow meter so there is never a lack of
fresh air.
Pressure Compensated Dry Compartments
There are a number of compartments within the SportSub
that contain components that will deteriorate rapidly if
they get wet. These compartments are the control panel,
battery box, junction box and thruster motors. Keeping
these areas dry requires compartments with either enough
strength to withstand the pressures at the maximum dive
depth or a means of pressure balancing. The SportSub
regulates these compartments so that they are at a
pressure just slightly above that of the surrounding
water. This ensures that any leak will allow air to
escape rather than water to seep in. This accomplishes
two things; it keeps components dry even when there is a
leak and it makes leak detection easy by watching for a
stream of bubbles.
Maneuvering Controls
The SportSub has to maneuver in two dimensions while
on the surface, and in three dimensions while submerged.
It moves forward, backward, up, down, and can even hover
and turn on the spot, a lot like the maneuverability of a
helicopter.
All maneuvering is accomplished with only two
thrusters, built in to the dive plains, and two control
handles. The thrusters are located so that their center
of thrust is at the same height on the hull as its center
of drag, so there is no tendency to nose up or down with
changes in thrust. The hull design also ensures that the
dive plane position is below the water line when the
SportSub is high on the surface.
One of the pilot’s hands controls the speed and
direction of both thrusters simultaneously, using a
single joystick. Each thruster’s speed is
continuously variable from full forward to full reverse
thrust. The pilot’s other hand controls the up and
down angle of the dive plains, which direct the thrust
and provide hydrodynamic force if the sub has forward
speed. By combining different thrust and angle
combinations, very precise control is accomplished in all
directions.
Fly-By-Wire Joystick
The thruster speed control joystick is actually a fly-by-wire
system, somewhat similar to what is used in military
aircraft. A computer actually reads the joystick position
and applies the appropriate speed settings to each motor.
Rather than directly change motor speed in relation to
joystick position, however, the computer ensures that
there is no harmful over-control of thruster speed
variation.
Indicators on the control panel provide visual
feedback to the pilot of each thruster’s speed and
direction by varying the illumination intensity of color-coded
directional arrows.
Electronic Buoyancy Control
Electronic buoyancy control is the true key to the
success of the SportSub design. Without automatic
buoyancy control, the pilot of an ambient pressure
submersible would be too busy adjusting buoyancy to
safely navigate and enjoy the dive experience.
Dangerously fast descents and ascents could occur if the
pilot ever lost control. The SportSub’s automatic
buoyancy control system keeps buoyancy constant
throughout a dive, regardless of depth.
The pilot initially sets neutral buoyancy manually,
since it is different with each set of passengers because
they have a different combined weight. Once neutral
buoyancy is set, the system is switched to automatic and
the electronic system takes over. As it senses
compression, while the sub is descending, it adds air to
the cockpit to maintain volume. When the sub is ascending
it allows air to blow out of the cockpit rather than
expand in volume. By maintaining a constant air pocket
volume in the cockpit the sub’s buoyancy remains
constant as pressure varies.
Automatic Depth Control System (standard on ResortSub and SurveillanceSub)
The new Auto Depth Control system uses 4 fixed position thrusters instead of the 2 variable position thrusters of standard subs. All 4 thrusters are computer controlled by a single joystick. There are three available modes of operation:
Manual Mode
Auto Hover Mode **
Auto Target Depth Mode **
** Includes Auto Ascent/Descent Rate Control
With Auto Depth Control engaged, whenever the vertical thrusters are not being operated manually, the computer takes control of the thrusters and uses them to hold the sub at its current depth. When the pilot wants to change depth, the thumb switch is used to ascend or descend. Once you have reached the depth you want, the pilot releases the thumb switch, and the computer again takes over and will maintain the new depth. Auto Rate Control is operational in this mode.
With Auto Target engaged, the pilot uses the thumb switch to scroll to a target depth as indicated on a digital readout, then releases control. The sub will ascend or descend (as required, to attain the target depth) and will hold at the target depth once it is reached. Auto Rate Control is operational in this mode.
The Auto Rate Control function or 'automatic ascent rate control and descent rate control', helps prevent the sub from ascending or descending too quickly (faster than 1 foot per second). This is a significant safety feature.
This is a basic overview of the Auto Depth Control System.
For a more
detailed description, click here.
Electrical Systems Monitoring
All the SportSub’s high current systems, from the
battery to the thrusters, are monitored continuously by a
computer. The computer detects any change in conductivity
such as a short or open circuit or any unexpected change
in resistance. It also monitors the temperature of
critical components and causes the thruster motors to
operate at reduced current draw until the components cool.
The computer also monitors the battery’s energy
level. This provides a real indication to the pilot of
the amount of charge left in the battery. It is far
superior to a voltmeter because the voltage of a battery
doesn’t change much until it is about to reach a
state of complete discharge. By then it may be too late
to take corrective action.
All of these monitored functions are displayed to the
pilot on one simple multi-color, multi-segment LED read-out.
Under normal operating conditions, the number and color
of lighted segments indicates the percentage of charge
remaining in the battery. If a single segment is blinking
it’s an indication that a fault has been detected in
the system. The operator refers to the owner’s
manual to identify the fault.
SONAR
Sonic Navigation And Ranging. This type of technology
has been used in military submarines since their
inception. In the early days SONAR systems were large and
cumbersome. Their displays were subject to interpretation
by highly trained and experienced operators.
Fortunately for us, modern electronics has
miniaturized and taken the guess work out of these
devices. In the SportSub a very sophisticated,
miniaturized, SONAR system provides ranging that can be
switched from measuring distance to an object in front of
the sub to beneath the sub. The combination of these two
ranging views provides valuable information for safe
navigation. The system analyzes all sonic echoes to
determine which might be false or multipath echoes. When
a true range is determined the system locks on, then
creates and maintains very accurate distance readings.
Range information is displayed to the pilot in the form
of a straightforward three-character digital readout.
ReservAir
The ReservAir system provides two essential emergency
backup functions. It consists of a manual override for
the electronic buoyancy control system and a completely
redundant air supply to all the SportSub’s systems.
The ReservAir tank is located within the nose of the
SportSub and its regulator and controls are completely
separate from the main air supply. If the main air supply
is depleted or has a malfunction of any kind, the
ReservAir system provides enough air to safely continue
the dive and bring the sub to the surface.
The other function of the system is the manual cockpit
air inlet. This valve allows the pilot to adjust cockpit
air volume manually in case of a failure of the
electronic buoyancy control system.
Drop Weights
The primary objective in any emergency situation is to
get the SportSub to the surface. Surfacing is normally
accomplished by simply pointing the dive planes up and
propelling the sub to the surface. If electrical systems
have failed there are several ways to surface the sub by
adding air to any of the ballast tanks, thereby
increasing buoyancy. In the unlikely event that both air
supply systems, and the electrical system, have failed,
or been depleted, it is still possible to surface the sub.
A series of ten pound drop weights are located in the
cockpit. The pilot can drop these out of the sub, one at
a time, until the sub begins to ascend. As it is
ascending the cockpit air volume will expand.
These drop weights can also be used as ballast trim
bars if a payload heavier than the buoyancy range is
required in the sub. For every trim bar removed from the
sub, an additional ten pounds of payload can be carried.
Removable SCUBA
SportSubs are equipped with removable SCUBA sets that
supply a mouthpiece regulator for each occupant. These
provide two functions; an emergency escape system, and an
excursion system.
Although there has never been a recorded case, it is
theoretically possible for a SportSub to become somehow
trapped under water or punctured in a way that prevents
the hull from retaining the air that gives it buoyancy.
If this should occur and the sub can’t be brought to
the surface the occupants could still surface by removing
the SCUBA sets and swimming out of the sub and up to the
surface.
In a much less ominous scenario the SCUBA sets can be
removed from the sub after it has landed on the bottom to
allow trained divers to take an extravehicular excursion.
Aesthetics
All of the above functionality in a simple shell of a
hull is technically elegant but it must also look elegant.
The combination of cockpit and hollow, bottomless,
ballast tanks could be shaped in almost any way that can
be imagined, as long as they have the required volume and
positioning. The goal of the SportSub design team was to
create a look that was unmistakably a submarine. The
image most people have of a submarine is a military
vessel that looks like a long tube with a round nose, a
conning tower, tail planes, and dive planes. Since the
SportSub is a miniature submarine we decided to create a
kind of caricature look - almost a cartoon version of the
real thing.
SportSubs are manufactured in different sizes and have
been painted in many different colors, in fact they are
available in any color a customer wants, but the shape is
unmistakably a SportSub.
Hull Construction and Finishing
The SportSub hull is constructed of fiberglass. That
statement in itself, however, doesn’t do justice to
the technologies that are incorporated. Fiberglass is a
generic term used to describe composite compounds of
fiber reinforced plastic resins but there are a wide
range of fibers, resins and construction techniques that
can make one piece of fiberglass as different from
another as tin is from titanium.
The SportSub hull is all hand laid using multiple
layers of woven and biaxial roving. Every seam is stepped
to a different width at each layer. All interior
components are joined with a curved interface filled with
a milled fiber composite to eliminate air pockets. These
construction techniques are more expensive and time
consuming than those used in most common fiberglass
products but are necessary to create a durable hull that
can be submerged repeatedly and withstand tropical
sunlight for many years.
The SportSub is not simply finished with an outer
layer of fiberglass gel-coat. It is sculpted and painted
in much the same way as a hand built automobile. The
paint is formulated to bond permanently to fiberglass yet
withstand water immersion and continuous direct sunlight.
It is harder and provides a better barrier to
deterioration than gel-coat does, yet presents a
smoother, more lustrous finish. Areas of the lower hull
that come in contact with the sea floor are protected
with heavy, dense polyethylene plates that can easily be
replaced if they get too badly scarred or cut.
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International VentureCraft Corp.
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