Max safe depth for goggles

[trux]

Well, I have no idea how the native divers manage to dive to 20m without bursting every vein in their eyeballs. Probably they do burst the veins anyway, but they don't know any better. One thing you can be sure of is that the wooden goggles are simply incompressible, and unlike modern goggles with silicone skirt, won't buffer any of the pressure. The pressure (or loss of volume inside the goggles - 1/2 the volume at 10m, and 2/3 at 20m) can be only compensated by pressing the goggles into the eye sockets or pulling the eyeballs out of the eye sockets.

Japanese amas did not use any goggles until the 1920's. Classical goggles were then quickly replaced with autocompensating models - you can see them for example here: Skin Diving History - Ama Goggles Hanging - AMA



Later, they started using oval scuba masks, and in diverse documentaries about ama divers I saw they use such vintage scuba masks until recent days.

Native divers in most regions dove without goggles, but for example Persian pearl divers already in 14th century were reported to use goggles with windows made of polished tortoise shell.

Polynesian divers used goggles without lenses - they were made of bamboo or carved in wood. The air trapped in them allowed for some visibility, but of course the divers had to keep looking down only, otherwise the air escaped.

You can find a very interesting document about history of goggles here: http://www.ishof.org/news/pdf/goggles.pdf

But frankly told, I'd recommend saving you the pain, and either using pipe goggles (plenty of DIY instructions here on Deeper Blue), or goggles with an attached rubber container for autocompensation - just like shown above on the photo of ama's goggles. Or when nothing else, then at least well compressible and relatively large goggles with silicon skirt.

 

[dimitris33]

Thanks for the link Ivo.

Surely I'm not gonna put my self in extreme experimental conditions to discover which of the goggles are capable safely take me to -10m.

I just asked and I'm still curius...!

 

[trux]

I just asked and I'm still curius...!

Well, with compressible goggles like the Aquaspehere Seal or similar, you can dive comfortably to ~5m. And you can go relatively safely deeper, just the comfort will be more and more reduced.

Remember not to tighten the strap on surface firmly, otherwise you lose the precious compressibility volume already before you start the dive. You have to keep the ratio between the uncompressed volume on the surface, and compressed in the depth, as big as possible, hence it is better having the mask pretty lose on surface. But then again, if you are cruising around with monofin, you can't have it too loose either, otherwise it will leak. You simply need to find the right compromise.

Better yet, make you the pipe or autocompensating mask, and you are quiet

 

[dimitris33]

That is a really straight to the point answer. Have a great w/end Ivo.

 

[trux]

Btw, I use several types of bigger goggles for sea swimming - Aquaspehre Seal XL, Cressi Swim, and one from Sommap (similar to the Sommap Flow, just without the nose pocket). The Cressi Swim has perfect vision - sharp and undistorted, but a relatively hard skirt - less comfortable for diving, and requiring a tighter grip on the surface to avoid leaking. Aquaspehre and Sommap have much worse view properties, but are softer and more comfortable. Sommap is softer, more compressible and better streamlined. There are also many other models of these big goggles on the market, and some may be superior. Look for ones with relatively hard lenses (the ones with soft lenses tend to give a distorted vision), and preferably with a harder connection between the two lenses (like the Cressi Swim) - that avoids double visions, and improves the vision too. Soft and relatively big (high) silicon skirt is good for compressibility.

 

[dimitris33]

I was reading last night the HomoDelphinus and this page came to my attention.

"In the center of the picture are goggles made of wood in different dimensions and these are the traditional underwater goggles used by all the fishermen divers of apnea around the globe. They have the advantage of diminishing the pressure because the wood breathes becoming permeable with water and does not hurt the skin.".



Would like to hear your comments on the breathing wood diminishing pressure.

 

[trux]

I am sorry, but no wood breathing would diminish the pressure inside the goggles, unless the goggles filled with water, which is probably the last you want. They may not hurt the skin too much, since the fit is custom made, and the contact area relatively large, but it has no impact on the pressure change and will lead to a barotrauma in depth.

In another thread, Rovanpera from Philippines wrote that the native divers equalize the goggles through the tear ducts. Unfortunately only very few people have the tear ducts open enough for allowing it, so if you can't easily blow air through them, you won't be able using goggles too deep (and especially not if they are not compressible like these wooden goggles).

 

[dimitris33]

Thanks Ivo. Have you ever tried wooden goggles? If so, what is the feeling? I can visualize that you will feel no pressure while going down as the wood cannot compressed comparable with the classic rubber goggles. So I can imagine the crushing of eyes will be done instantly with no warning signal (the pressure feeling of rubber).

No?

 

[trux]

No, I did not try any wooden goggles, Dimitris.

I can visualize that you will feel no pressure while going down as the wood cannot compressed comparable with the classic rubber goggles.

Goggle squeeze happens exactly for that reason - incompressible goggles, and the pressure lower than the ambient pressure of water. It is not the high outer pressure that is harmful to the eyes when diving with goggles, it is exactly the opposite - the low air pressure inside of the goggle due to their incompressibility sucks in the eyes (since the pressure inside the body is equal to the ambient pressure), and the pressure exploses the veins in the eyes. So if you have any kind of incompressible goggles, such as wooden or plastic with no big silicone skirt, there is practically no equalizing room, aside from the goggles being pressed a bit deeper into the eye sockets / or the eyes entering a bit deeper into the goggles, so it is the worse case scenario.

 

[rovanpera]

I was trying out wood goggles just yesterday. unfortunately they flooded immediately on me, the fit wasn't very good, but my buddy Wolfgang dove down to 15-20m with them with no flooding and feeling fine. We had a few different models to try out. Wolfgang also commented that he never saw any local divers losing air from the goggles on ascent, so the tear duct equalization is a bit of a mystery. I can push air from my tear ducts but it needs quite a strong effort and I don't know if I could equalize goggles with it...

 

[dimitris33]

That is a great statement rovanpera! Offcourse a short dive video of your buddy would eliminates everyone doubts!!

 

[trux]

Very interesting! Basically, at non-compressible (and non-leaking) goggles, the only way to compensate the pressure in them is either by decreasing their inner volume (pressing them deeper inside the eye sockets, or pulling the eyes or surrounding skin deeper iside the goggles), or the earlier mentioned equalizing through the tear ducts. Personally I do not see any other possibility (wood breathing does not make any sense), so it would be indeed very interesting to see a closeup video of the goggles during the dive. Could Wolfgang repeat the dive holding an UW camera in his hands pointed towards his face the entire dive (descent plus ascent)? I guess it is Wolfgang Dafert from Freediving Philippines - Freediving Courses and Outdoor Adventures in Moalboal, Cebu, and I am sure he has a UW camera somewhere around. It would be very interesting seeing what actually happens inside the goggles, and where the 2/3 of its volume go at the 20m depth.

 

[Simos]

Dimitri I'm slightly confused are we still discussing what would be a good practical alternative to a mask for you to use for dives up to 10m or just a general theoretical discussion about wooden goggles that were handmade or made in 1940?

While I'm intrigued as well about the wooden goggles just out scientific curiosity, I personally wouldn't really spend much time researching this as a serious option - my (non-educated) guess is that they either simply leak or that they are sufficiently low volume to allow for (questionably) safe dives to those depths My guess is also that they will offer rubbish visibility compared to alternatives...

If you don't want to go down the route of a pipe-mask etc I would recommend the aquasphere goggles (as per my previous post). As mentioned, they are very comfortable for me at 3m leading me to believe that you could go deeper with them and interestingly, Eric (Fattah) reckons you can go to 15m-17m with them if you fully inflate them before you dive: http://forums.deeperblue.com/beginner-freediving/87307-depth-diving-goggles.html

I don't know what this depth is based on (i.e. either calculation or practical experience) - hopefully Eric might be able to chip in to the discussion..

 

[dimitris33]

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This thread is getting so interesting.

I have already ordered wood goggles from Wolfgang. Either will be a nice piece for my freediving collection to have or a real surprise to my dives!!

Maybe is the rubber acting like a sucker sucking the eyes with the classic rubber goggles. Wood on the other hand cannot compressed and therefore only the inside low pressure sucks the eyes BUT what is the limit between those two???

Maybe the rubber with low pressure is worst than the wood with low pressure allowing to dive deeper....

Simos indeed the thread was to find some way to dive around -10 with no mask, fluid goggles or pipe mask. It interestingly turned on the wood goggles and would like to stuck on this discussion as it is intrigued me too a lot. Especially after the last night reading of homodelphinus page..
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[Simos]

Yes interesting for sure I've seen wolf's video too, how deep was that? I stand by my previous guess, I think the wooden goggles are very low volume ie it's not the wood vs rubber that makes the difference but the actual design of the goggles.

Just a guess though - am I even right in thinking that lower internal volume would cause less outward pressure on the eyes?
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[Simos]

By the way check out swedish goggles - they use a similar principle to the wooden ones ie they rely on their shape rather than suction to keep the goggles on the eyes. Obviously any goggles that rely on suction don't help as you are starting with pressure on the eyes even on the surface (unless you wear them really loosely which was previously suggested on this thread).
Ps i am not suggesting you dive deep with Swedish goggles
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[trux]

Just a guess though - am I even right in thinking that lower internal volume would cause less outward pressure on the eyes?

Sure, at 20m, at incompressible goggles, you need to reduce their inner volume to 1/3 to equalize the pressure. So if they are already low volume, the 2/3 will be smaller than at bigger goggles, and hence easier to achieve by pushing deeper and sucking the eyes and/or surrounding tissue into. Still, they are plenty of really low volume plastic goggles, but I would not try diving with them to 20m. The rubber/silicon sealing has little impact, as long as it is not thick enough to take in some of the volume change. I can only imagine that the good seal of the silicon helps creating some under-pressure already on the surface, because most people tighten them pretty strong, or push inside on the surface to make the seal through the vacuum effect (EDIT: ah, Simos mentioned it above too - I did not see it before posting)

Not sure how is the design of the wooden goggles, but the ones on the pictures above do not look having lower volume than common swimming goggles. Rovanpera can perhaps tell us better.

Another thing to be wary at the wooden goggles is the glass - from what I read, ordinary glass is used, so in case the lens implodes, you can suffer a serious injury.

 

[Simos]

Another thing to be wary at the wooden goggles is the glass - from what I read, ordinary glass is used, so in case the lens implodes, you can suffer a serious injury.

This was my initial reaction too when I saw those instructions from 1940... Hopefully wolfgang's goggles don't use plain glass?
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[trux]

Well, it is very difficult to cut tempered glass, so if he does not use plastic instead, I am afraid it will be ordinary glass

 

[Simos]

Well hopefully the glass is thick enough then

I think a better solution is, instead of goggles, to wrap a few rounds of cling film around the head.
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