One major advantage to the SportSub design is the intensity of the experience. Unlike a closed sub experience, which is a lot like sitting in a chair watching a monitor about the underwater world, a SportSub experience is more like entering an alien world. Passengers describe it like a trip to a foreign planet. You also feel the pressure and hear the sub’s automatic buoyancy compensation system working so you feel more in tune with your environment.
More positive reasons include:
The greatest advantage of swim-entry is safety. The simple rear opening can never get stuck or jammed shut, trapping occupants inside. Occupants can readily escape from the SportSub by swimming out.
Since the SportSub works in a balanced pressure system, the hull isn’t required to contain enormous pressure and can never be crushed by external water pressure. It is also immune to leaking. If a hatch in at the top of the cockpit in a closed system were to leak, all the air would escape and buoyancy would be lost. The SportSub design eliminates this problem.
A third safety feature of the swimming entry is that operators and occupants are more confident. 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 more confidence that passengers will be capable of handling a ‘worst case’ emergency situation. The system also makes underwater adventures more available to passengers who might otherwise feel uncomfortable in an enclosed space.
The SportSub is the “ultralight” of submarines. In fact the ultralight aircraft revolution of the 1980s was part of the inspiration for its design. The intention was to develop a sub that could be safely and easily operated and maintained by any competent individual anywhere in the world.
The ambient pressure principle also allows easy exiting of the sub without using a lockout chamber. Occupants are always equalized to the surrounding water pressure.
The weight of any dry submersible is dictated by its internal air volume. The weight of a sub must always be exactly equal to its buoyancy, most of which comes from the air inside it. If the internal air volume can be reduced, the weight can be reduced. The SportSub design provides a very small internal air chamber because the occupants are half submerged in water. This is not possible with a One Atmosphere design so they are inevitably heavier.
Added weight increases the required strength of all handling equipment. This in turn increases the weight and cost of the handling equipment. If the sub had twice the internal air volume it would weigh about one thousand pounds more. If it did weigh one thousand pounds more, the weight of a davit to launch and recover it from a boat deck may also weigh a thousand pounds more. The added weight carried by the boat would probably double. What this means is that a significantly larger boat would be required to carry, launch, and recover the sub if it weighed more. This fact is particularly critical when a boat is designed specifically to carry a sub and passengers to a dive site in a tourist operation. It also allows owners of smaller boats to enjoy the advantages of taking their own submersible wherever they go.
Another benefit of the open hatch approach is cost. Our hatch solution is free! A good quality sealed submarine hatch could easily cost as much as an entire SportSub.
Another primary objective of the SportSub design is to keep the cost low enough for personal recreational use and for profitable tourist ride operations. To meet this objective, consideration was given not only to the initial purchase price but also to the cost of ongoing maintenance as well as auxiliary equipment required for operation, including launch and recovery. Closed One Atmosphere designs do not meet any of these objectives for the reasons explained previously. They are too heavy, require specialized air supply equipment and maintenance, and they cost many times more to manufacture due to their complexity. Wet Sub designs do meet the cost objectives but are restricted to use by qualified SCUBA divers and therefore do not provide the ability to offer rides to friends and/or paying passengers. A Wet Sub also doesn’t allow occupants to talk normally with each other and share the dive experience.
Jumping in a typical pressure vessel sub can be a little like taking a green house out for a spin. The light refracts through the windows and heats up the cockpit and can get very hot and uncomfortable. The SportSub design counters this because you can easily cool off with the surrounding water. Simple and effective.
In additional to cost, the absence of stress on the hull also reduces its complexity and overhead. A traditional One Atmosphere submersible is designed according to rules dictated by an association such as the American Bureau of Shipping. These rules require that every component be marked and catalogued and that only licensed technicians do the maintenance. They also require that every sub be tested and inspected annually by a representative of their organization. All of these activities add cost and complexity and are time consuming. The SportSub is designed to be easy to operate, support, and maintain, using only the type of systems required to support SCUBA activities. This equipment is readily available worldwide and is a fixture on many larger boats and yachts where diving is a recreational or commercial activity.
The SportSub design using the Ambient Pressure principle provides the ideal solution for recreational submersibles and certain commercial operations. The diving experience is superior, maintenance is simple, the cost is minimal, handling is easy, and operation is practical. These subs can be enjoyed anywhere in the world, including tropical islands or aboard yachts or commercial vessels.