Defogging your Full Face Mask
Like your defog capability in your car, the efficacy of mask defog is effected by temperature and surface tension conditions on the surface of the visor. Everyone knows surface tension will cause fogging to occur at different levels. Of course, we don’t want to apply anything to the visor and that’s a feature of the Guardian mask. However, like your automobile windshield, temperature and moisture on the visor prior to the dive will affect the level of clearing that can be expected. In your car you notice that it takes some time for the engine to warm up and therefore produce hot air before defogging occurs. In a diving mask, we don’t have the luxury of blowing warm air over the lens. So, we rely on air blowing over the surface of the visor to evaporate the moisture.
Problems may arise when the inner visor surface is wet before the dive. Water on the surface of the visor, without any anti-fog agent can be problematic. This is because the only way to remove the moisture is to completely dry the surface of the visor. Since we are no longer talking about a mist of moisture but rather much more water it is obvious it will take much longer, if ever, for the visor to become dry enough for defogging to occur. Fogging issues are rarely a problem when the dive is initiated with the inner surface of the visor dry. There can be some exceptions where just the right conditions occur and defogging is more difficult. However reports of this happening are rare indeed. If this condition occurs, then perhaps the remedy is to use a defog solution. If you dive and have persistent fogging, and it’s due to a wet visor inner surface, it is advised to surface and have the visor inner surface dried with a soft non-abrasive towel.
Redundant gas supplies/systems
There are several gas switch blocks/manifolds on the market to allow you to use an additional or redundant gas supply or surface supply. Out of Air (OOA) emergencies can manifest themselves in several ways. It can be as simple as running out of air or an equipment failure that causes a depletion or immediate cutoff of the diver’s air supply. Redundant gas/bailout systems will allow for the diver to switch to an alternate gas supply carried by the diver to provide for self sufficiency. A pony bottle with the first stage and low pressure hose piped to a gas switch/manifold block will allow for switching to a backup supply. In the event that there is an equipment failure downstream (between a gas switch block and GFFM) an alternate second stage regulator attached to the first stage of the pony bottle will provide for full redundancy. Any first stage regulator that has the capability to be shut off from the second stage with the use of a gas switch block/manifold must have either another second stage regulator directly attached to the first stage or must have an over pressure relief valve (OPV) mounted on a low pressure port. In the event a first stage regulator fails, in that the intermediate pressure spikes, either a second stage regulator or OPV will allow the excess pressure to bleed off.
Diving in questionable or contaminated Water
Diving in contaminated water requires specialized equipment and training as well as decontamination protocols. This course does not cover, nor qualify, the end user in diving in Hazardous/contaminated environments. Several issues can be addressed when diving in questionable water though. Consider all water, unless diving in pristine environments to have some level of contaminants.
A full face mask, used in combination with an appropriate dry suit with an attached latex hood and dry gloves will provide the diver with total encapsulation and a level of protection from contaminated water. However, this system is only as good as the integrity of each component. This system can provide a limited amount of protection for low levels contamination. Any indication of significant amounts of contamination should only be dived by those with the proper equipment, knowledge, training and experience.
Consider keeping the inside of the mask as dry as possible. Put the mask on on the boat, take the mask off on the boat. Never remove the mask while in the water and allow it to flood or soak unless absolutely necessary in case of an emergency. If there are pollutants in the water, the mask is now contaminated. By donning the mask and breathing, anything in the mask that a diver would want to avoid will now be misted and delivered to all the mucus membranes between the chin and eyebrows, into the deepest recesses of the lungs, sinus, digestive track and eyes.
Any mask that becomes contaminated should be taken out of service immediately and cleaned/decontaminated.
Using the ABV is especially helpful in maintaining the integrity of the mask. Always close the ABV prior to diving. Be aware the ABV could be an entry point of small amounts of water. Inverting while diving with the ABV open will result in the mask flooding.
A note about hoods and seals
To get the best seal, the mask skirt should be fitted directly to the skin of the diver’s face. Do not attempt to seal over or against a neoprene hood. This will result in leaking, excessive gas consumption and hood inflation. With the mask leaking, due to the neoprene violating the seal, there is a tendency on the part of the diver to attempt to resolve this by tightening the mask straps to the point of damaging the skirt at the buckle attachments. It also stands the mask off of the face, altering the equalizing assembly adjustment. A neoprene hood can be trimmed to allow for the mask to seal properly against the face. For drysuits that have latex seals, the mask can be worn directly over the hood. This type of hood allows for the mask to seal properly over the hood and the hood seals to the face.
Pulling a hood over the head harness is not recommended. This makes adjustment of the mask difficult as well and any emergency bailout.
Recommendations for trimming a neoprene hood
First, you are trimming at your own risk, OTS accepts no responsibility for any damage, miss-cuts, bad fits or slips of the scissors to neoprene hoods or other equipment. These are recommendations only. Some hoods do not require trimming. You can also roll or fold the chin of your hood to clear it from the chin pocket.
With the hood on and properly positioned, mount the mask as you would normally wear it. Chalk around the skirt of the mask to the hood. Remove the mask and hood. Mark about 3/8 to 1/2 inch inside of the line along the top of the forehead tapering to the inside of the line at the cheekbones. Now carefully cut with a sharp pair of scissors, following this chalk line. Cut on the inside of the line. The forehead of the hood seems to always pull back if you cut it to the line exposing your forehead. This should provide you with a good fit of the hood to the edge of the skirt. Cut carefully unless you have a supply of extra hoods. Treat any stitched seams with AquaSeal® or other neoprene cement.
Myths and misconceptions
Full face masks are dangerous. The act of breathing underwater without proper training is inherently dangerous. Full face mask diving should be considered as an advanced skill set. With proper training and preparation, diving a full face mask will enhance safety. Imagine going unconscious while diving with a standard bite
mouthpiece regulator, the diver’s fate would be fairly uncertain. With a full face mask, a breathable environment is literally strapped to the diver’s face at least affording an opportunity of survival. Out of air (OOA) situations are more complicated with a full face mask in that you loose your vision at the same time as your regulator if you bailout. Using a redundant gas supply with a block provides an alternative to bailing out under some circumstances. Bailing out as previously described needs to be practiced and second nature.
Full face masks waste gas when learning to dive a full face mask. A diver may use more air than with a standard regulator. However, the more comfortable a diver becomes with the Guardian, her or she may find that their gas consumption is near or the same as with a bite mouthpiece regulator.
Full face masks fog and are prone to CO2 accumulation. As describe in this training, neither are the case.
They leak. With the regulator being the lowest point of the mask in the average swimming orientation, the mask is pressurized. The mask, in general, will leak air out as opposed to water in. If the diver inverts, in that the regulator is higher than the airspace of the mask, the mask no longer has a positive pressure and may leak water in if the seal is broken. This is something you will learn is you leave the ABV open prior to submersion.