Things to consider before buying a cave diving helmet:
"Cave diving helmets" have three uses:
1) mount your GoPro or other action cam (and no lights) on your helmet for reasonably stable video - even in open water. Hence, it is one of a videographers tools.
2) protect your head from bumps while diving in zero visibility sumps and/or while crawling from sump N to sump N+1 (even if the sumps were clear); head mounted light is very much needed in those dry sections of cave. Thus, it is a sump divers tool.
3) free your hands for actual labor during search and recovery diving, inspection diving, and other underwater work. A hand held or canister light might cause unnecessary trouble if you had to take a significant amount of notes underwater where you need to hold wetnotes or a slate and a pencil and a light and you happen to only have two hands. Hence, it can support workplace lighting.
The helmet can also cause some trouble:
1) If it tilts forward and dislodges your mask repeatedly, then you need a different kind of helmet that leaves more free space for the mask.
2) If you are a sump diver and you need to remove your helmet to fit trough a narrow section of the cave, and you wear gloves, then the chin strap can become a problem (hint: rubber band instead of clipped chin straps makes life simpler). The same situation occurrs if the helmet dislodges your mask and you need to temporarily remove the helmet to adjust you mask.
3) Helmet mounted lights generally suck, but sump divers and those who work underwater may not always have a choice. Sometimes one just needs to have the hands free.
4) A helmet could interfere with gas sharing (the longhose) - especially if there are protruding helmet mounted lights. In sump diving the benefits of a helmet outweight this one drawback. The same is probably true if you do actual work underwater and need your hands free. Videographers should take note, though. Make you choice, know its implications, and plan accordingly.
5) Helmet mounted lights can dazzle your buddy (and hence need to be used with care). This is especially true in darkness and in emergencies. In sump diving the benefits of a helmet outweight this one drawback. The same is probably true if you do actual work underwater and need your hands free. Videographers should take note, though. Make you choice, know its implications, and plan accordingly.
What kind of helmet, then?
--> A low profile helmet that leaves ample space for the mask and that is easy to take off. The helmet does not need padding - your neoprene hood should be about adequate for that. And make sure that it is neither excessively heavy nor buoyant. Air must also be able to escape (as your exhalation bubbles will find their way into the helmet). Hence, it needs to have vents. Make sure that you can attach you camera and/or lights on the helmet.
"Cave diving helmets" have three uses:
1) mount your GoPro or other action cam (and no lights) on your helmet for reasonably stable video - even in open water. Hence, it is one of a videographers tools.
2) protect your head from bumps while diving in zero visibility sumps and/or while crawling from sump N to sump N+1 (even if the sumps were clear); head mounted light is very much needed in those dry sections of cave. Thus, it is a sump divers tool.
3) free your hands for actual labor during search and recovery diving, inspection diving, and other underwater work. A hand held or canister light might cause unnecessary trouble if you had to take a significant amount of notes underwater where you need to hold wetnotes or a slate and a pencil and a light and you happen to only have two hands. Hence, it can support workplace lighting.
The helmet can also cause some trouble:
1) If it tilts forward and dislodges your mask repeatedly, then you need a different kind of helmet that leaves more free space for the mask.
2) If you are a sump diver and you need to remove your helmet to fit trough a narrow section of the cave, and you wear gloves, then the chin strap can become a problem (hint: rubber band instead of clipped chin straps makes life simpler). The same situation occurrs if the helmet dislodges your mask and you need to temporarily remove the helmet to adjust you mask.
3) Helmet mounted lights generally suck, but sump divers and those who work underwater may not always have a choice. Sometimes one just needs to have the hands free.
4) A helmet could interfere with gas sharing (the longhose) - especially if there are protruding helmet mounted lights. In sump diving the benefits of a helmet outweight this one drawback. The same is probably true if you do actual work underwater and need your hands free. Videographers should take note, though. Make you choice, know its implications, and plan accordingly.
5) Helmet mounted lights can dazzle your buddy (and hence need to be used with care). This is especially true in darkness and in emergencies. In sump diving the benefits of a helmet outweight this one drawback. The same is probably true if you do actual work underwater and need your hands free. Videographers should take note, though. Make you choice, know its implications, and plan accordingly.
What kind of helmet, then?
--> A low profile helmet that leaves ample space for the mask and that is easy to take off. The helmet does not need padding - your neoprene hood should be about adequate for that. And make sure that it is neither excessively heavy nor buoyant. Air must also be able to escape (as your exhalation bubbles will find their way into the helmet). Hence, it needs to have vents. Make sure that you can attach you camera and/or lights on the helmet.