Most divers have found themselves in a situation requiring unusual reserves of energy. It may be when swimming into a current; positioning an anchor; assisting a distressed diver, or during a long surface swim back to boat or shore.
Whenever these situations occur the diver will usually experience changes in the breathing pattern. Unless steps are immediately taken to restore breathing equilibrium the partial pressure of carbon dioxide present in the diver’s body will increase, resulting in a rapid, shallow breathing rate that in turn can lead to the onset of panic.
Posed with solving this dilemma quickly and inexpensively, Zymurgy Inc.’s design team – the international consortium of diving technologists whose previous achievements include the ‘Uranus’ nitrox snorkel and the ‘Mollusc Fu-2’ diving computer – have developed a fin featuring an independent, ‘power-on-demand’, booster device.
Constructed of heavy thermo-rubber with a stocky, wide angle blade and lateral power vents, the ‘Missile Fin’ bears a striking similarity to the classic design of the ubiquitous ‘Jet’ fin. An open heel model employing an expanding stainless-steel spring and rubber heel pad in place of adjustable straps, the ‘Missile Fin’ functions as an ordinary fin – until additional power is required.
The ‘Missile Fins’ energy drive is provided by super-charged cartridges of CO2, (similar in size to those formerly used on BCD’s), fastened to the outer edge of each fin, slightly forward of the heel spring assembly. Housed within an elliptical, open-front casing mounted onto the fin, the CO2 canisters are activated by a unique trigger mechanism. Passing through the upper part of each housing, rip-cords pass up the side of the diver’s outer leg and are secured to the upper thighs by adjustable metal clamps.
“Because of the need to discharge both cartridges simultaneously if the diver is to avoid spinning around in circles – a problem that we encountered during early trials with the ‘Missile Fin’,” says David Strike, Zymurgy Inc.’s, Founder and Associate Design Engineer, “the thigh clamps are joined together by a series of thin, telescopically opening, ball-and-socket rods with a central, downward pointing, lever mounted at crotch level. To activate the device the user simply reaches between their legs and pulls firmly upwards on the lever. It may sound unnecessarily complicated, but in practice it works extremely well.
“The additional thrust provided by the booster device is sufficient to propel the diver through the water at a maintained speed of three knots for an average distance (depending on build) of twelve metres.” He added. “However, because of the problems of barotrauma associated with sudden ascents and descents, we have included a safety over-ride in the features of the ‘Missile Fin’.
“Two miniature hydrostatic sensors are located fore and aft within each unit, devices that only permit operation when the diver’s body is angled within 15 degrees either side of the horizontal plane.”
Quickly disassembled for easy maintenance and to allow quick cartridge changes, each set of ‘Missile’ fins comes complete with four spare CO2 cylinders.