There are a number of good reasons why a person should join hand to nose, but equalizing the middle ear is not one of them. It is awkward, unaesthetic, and decidedly not hydrodynamically efficient. It is a drag. Unfortunately, for the general run of freedivers, squeezing the nostrils shut is what makes equalizing possible. Few can do without the helping hand. Those who can are the envy of all the rest.
Now, to be sure, freedivers willing to forego the luxury of underwater vision have always been able to clip their noses shut and thereby dive hands-free, sans the mask with its dead air space whose pressure has to be equalized during descent by pumping air into it through the schnoz. Can’t pump air through a schnoz clamped shut with with an aquatic Vise-GripTM , so clamped nose meant no mask and terrible vision. Conventional goggles were never a solution, insofar as there was no feasible way to get air into them at all.
But now, be of good cheer all you handily handicapped, glottally challenged and pharyngally phrustrated, for science and engineering now offer a couple of ways out. If one is willing to accept and adapt to the trade-offs, technological solutions are reaching a level of maturity which merits consideration.
Fluid goggles have been around for several years, and are now offered commercially by designer Eric Fattah, an engineer and constant ballast world record setter. The concept is quite simple: rather than retaining dead air, which would be subject to intolerable compression after only a few meters’ descent, fill the goggles with a non-compressible fluid. But then, the skeptic is quick to ask, if we are going to fill the goggles with fluid, why have goggles at all ?
The answer is vision. LiquivisionTM fluid goggles provide a physical platform for an optical system that, in principle, can correct for the refractive properties of the fluid medium and yield serviceable underwater vision to the human eye. This is accomplished by integrating special optics into the goggles’ eyepieces. The trick is in designing the lenses. This is a pretty unusual problem in optical engineering, managing a chain of refraction through two fluids ( the ocean and the fill fluid) and at least two solids ( the goggles and the optical system components) before the light reaches the cornea.
LiquivisionTM fluid goggles have the overall look and feel of ordinary swim goggles until, on closer examination, one notes the lenses mounted on the inside surfaces of the eyepieces.
I first tried them on dry, in my living room, and could not see a thing. The effect was similar to what it might be were the goggles filled with colorless petroleum jelly.
Following instructions in the excellent 14-page user manual, I then filled each eyepiece with one of the recommended Bausch & Lomb saline solutions of the sort used to soak contact lenses.
It was a bit awkward and messy the first time around – most of the fluid seemed to end up running down my cheeks. I had the devil’s own time with the last little air pockets, but finally managed to fill the eyepieces. A complete fill is very important : any air remaining inside would be compressed during descent and the resulting squeeze would in the best case limit one’s depth (ouch !) and in the worst cause injuries such as popped blood vessels on the eyeball.
During the filling procedure there comes a magic moment, a phase shift when the fluid level covers the top of the optical portion of the cornea and suddenly one can see. My vision with the goggles was not excellent. It was a little blurry, and there was some defraction resulting in rainbow halos. I never managed to adjust the LiquivisionTM fluid goggles to a state in which I could read the display on my Mares Apneist freedive computer. Nonetheless, I was pleasantly surprised by the functional utility of the vision I did achieve, and moved on to the in-water testing.
A buddy and I tried out the LiquivisionTM fluid goggles in the Royal Navy Submarine Escape Training Tower, HMS Dolphin , in Portsmouth, England. Crispin had about the same difficulty as I did getting the goggles completely filled, but once he did, his vision was excellent. He easily read the small digits on his dive computer, and impressed all those present by reading a digital video display across the room, at a considerable distance. His comfort and vision underwater were excellent as well.
I had no trouble filling the goggles at Dolphin, but my vision was about the same as it had been at home. As soon as I began to dive, though, I became very forgiving of this. The hands-free freedom was like a gift from heaven. I’d been a hands-free equalizer in my younger days, and there, in the tank with the LiquivisionTM fluid goggles, I began to wonder how I’d been able to persuade myself to keep diving once I’d begun to rely on the nose-pinch. There is no question about it: free-falling with both hands leading is way more streamlined than the hands-on posture can ever be, tuck the elbow as you will. After a short while I forgot all about reading my gauge and began to enjoy the color and light. I was easily able to demonstrate that spotting and grabbing a tag in the constant ballast scenario would be no problem at all.
The LiquivisionTM fluid goggles solution yields an additional benefit which increases in value with depth. Equalizing a mask, however low-volume it may be, has a price tag denominated in cubic centimeters of precious air, air which could otherwise be retained in the lungs or rationed out to equalize the middle ears, both of which are on the critical path to deeper descents. By the time a masked freediver reaches 40 meters, he’s had to feed that mask the equivalent of about 500cc of the air taken into the lungs at the surface. I know I’d rather keep half a liter more fresh air in my lungs ! While some of this air can be recovered during the ascent as it re-expands, it unavailable at depth for ear equalization or general metabolic uses.
LiquivisionTM fluid goggles don’t require equalization and so make available a significant additional volume of air for those mission-critical functions that can carry one to new personal bests, or, for the very best among us, to new world records.
The LiquivisionTM fluid goggles are winners. For some people, they are an overall step up from low-volume masks, providing vision suited to soul diving the reef or even spearfishing. For others, vision is not quite that good, but good enough for the tasks associated with constant ballast diving on the line.
It is important to understand that due to differences in physiology, the quality of vision achieved with Liquivision fluid goggles varies from one person to another. In my case, my vision was acceptable; in Crispin’s case, his vision was nearly perfect. Although there’s no way to know in advance exactly how clear your vision will be, the manufacturer does offer a 30-day money back guarantee in case you’re not satisfied The goggles come in two optical configurations, and I suspect that most people will be able to attain satisfactory vision with one of the types and with a bit of adjusting. The fill procedure can be expedited by attaching an ordinary basketball inflator pin to the nozzle of the saline bottle and in this manner injecting the saline into the eyepieces after donning the goggles.
In any case, the amicable divorce of hand and nose is liberating and enabling. As additional lagniapes, Liquivision tm fluid goggles are immune to fogging and are more hydrodynamically efficient than any mask. Great fun !
LiquivisionTM fluid goggles (www.fluidgoggles.com) are currently offered direct from manufacturer at $US 295.
In Part II , we’ll have a look at a novel, eccentric but very functional re-incarnation of an old concept in hands-free equalizing solutions.
