Max safe depth for goggles

[Andrew the fish]

I made a streamlined version of the goggle-bulb design; the bulb sat on top of my head under my swim cap. It did not work well, the bulb was too rigid, thus I needed extreme squeeze on my eyes before the bulb would start to collapse and transfer air. For this to work the bulb must be very soft.

I have bicycle tube and clear capillar tube and disposable pair of goggles. Bicycle tube will be going around along with the strap, connecting two eyepieces. The only problem now is finding small enough brass fittings to connect cleartube to goggles. Could use lot of goo but it won't be aestetically pleasing. And I think bicycle tube will be too soft and will not self-inflate on the surface.

 

[hteas]

Simos,
For me at least, the way to understand the physics if that there is a rigid little pressure vessel over each eye which sits on a solid surface (bones) with a tissue seal. As you descend the pressure in each vessel will stay at 1 atmosphere until failure (at an unknown depthbut well beyond the normal assumed maximum depth fo 3-5 m). This is so because the goggles and the bones of your face are solid, and therefore not affected by the change of pressure (they have no airspaces within them)
I agree that there is no unlimiteed depth potential, but it has been shown to be quite deep. There are 3 sources of failure, two of them potentially catastrophic.
1) a lense may break, causing a sudden rush of water and glass fragments into the vessel. and potentially into your eye
2) a leak may develop around the seal provided by your skin, filling the vessel with water until the internal pressure is equal to the external pressure, like Dimitris found.
3) sinuses in your head, being at ambient pressure since you have to clear them, "may" break, causing air and blood to fill the vessel. This one is a real unknown, since I have never heard of anyone having this result, and the offending sinus would have to be directly under the 1 atmosphere vessel. Not sure that this is more than a figment of an overactive imagination, and it doesn't seem too likely, but very painful if it did occur.

Beyond these 3, what mechanisms can you describe to cause failure?

 

[hteas]

Walrus (Walter Steyn) several years ago had a pair of swimmers goggles that he modified for depth. He connected the 2 sides witha tube, and had a second tube from one eyepiece to his mouth. he added air as needed on a dive. It worked for him, and was very clever, but way too much thinking involved for me.

 

[Simos]

Simos,
For me at least, the way to understand the physics if that there is a rigid little pressure vessel over each eye which sits on a solid surface (bones) with a tissue seal. As you descend the pressure in each vessel will stay at 1 atmosphere until failure (at an unknown depthbut well beyond the normal assumed maximum depth fo 3-5 m). This is so because the goggles and the bones of your face are solid, and therefore not affected by the change of pressure (they have no airspaces within them)
I agree that there is no unlimiteed depth potential, but it has been shown to be quite deep. There are 3 sources of failure, two of them potentially catastrophic.
1) a lense may break, causing a sudden rush of water and glass fragments into the vessel. and potentially into your eye
2) a leak may develop around the seal provided by your skin, filling the vessel with water until the internal pressure is equal to the external pressure, like Dimitris found.
3) sinuses in your head, being at ambient pressure since you have to clear them, "may" break, causing air and blood to fill the vessel. This one is a real unknown, since I have never heard of anyone having this result, and the offending sinus would have to be directly under the 1 atmosphere vessel. Not sure that this is more than a figment of an overactive imagination, and it doesn't seem too likely, but very painful if it did occur.

Beyond these 3, what mechanisms can you describe to cause failure?

Hey Hteas

I think this will happen:

http://4.bp.blogspot.com/_iYug41WbzfU/TIgJfgvHXzI/AAAAAAAACMM/pZx8vU7Xdcw/s1600/mask+squeeze.JPG

http://www.bsac14.org.uk/photo/general/masksq.jpg

 

[Simos]

By the way, although I'm sure it's obvious; those are images of mask squeeze.

It's not hypothetical and there's lots of info on it, I'm sure you must be familiar with it. In a nutshell as you descent with a non-equalised mask, the pressure differential between the airspace in the mask and the capillaries and soft tissue in and around the eye causes a barotrauma to these tissue/capillaries.

I'm sure if people get it while on scuba and with a mask with a nose piece, you can get it as well while freediving with goggles.

The other things you mention can happen too of course (e.g. the glass shuttering) so all in all, while I think wooden goggles are cool and I might consider buying some as a keepsake, I wouldn't personally take them down to 20m from what I've seen/read, especially if they fit well. If they flood of course it will be safe.

 

[Azrael3000]

Hteas once again, you make the same mistake that I made when I wrote my initial post in this thread. Your eyes are not solid. In your sealed capsule they are the only thing that is not solid AND they are under pressure (as is the rest). So say you're at 10 meters, then assuming you have 1 atm in your goggles you have 2 atm everywhere else. That means there is a suction created from the lower pressure inside the goggles. How can it be compensated? You say it can't. I say well let's look at the components:
Lenses, can't be they are solid
Frame, same
Bones, same
Eyes: yes! they can move. In fact they are the only part that can move so they will to equalize the pressure differential. That means the eyes get sucked into the goggles (as there is lower pressure there) until the pressure inside the goggles is 2 atm as well. Of course that puts quite a strain on your eyes the deeper you go as they are not supposed to be pulled out of their sockets, so it happens what is quite impressively shown in Simos pics.
So to summarize, your eyes will move and to a certain extend they can and because of that it is possible to dive to 10 m or so if the goggles have very little volume. But the deeper you go the more strain is on your eyes and mask squeeze will be the result.

 

[growingupninja]

I have bicycle tube and clear capillar tube and disposable pair of goggles. Bicycle tube will be going around along with the strap, connecting two eyepieces. The only problem now is finding small enough brass fittings to connect cleartube to goggles. Could use lot of goo but it won't be aestetically pleasing. And I think bicycle tube will be too soft and will not self-inflate on the surface.

I was gonna try something like this with a pair of swedish goggles, tubing, and a whoppee cushion. I have everything but I need aquaseal and am waiting to buy the tube when I have some additional uses. I have a feeling it will be obnoxious to dive with and plastic swedish goggles do not offer the clarity of a tempered glass mask, however a bicycle tube could be incorporated into the strap.

 

[wdaf]

For info, safety reasons and also always happy about ideas and feedback ...

About wooden goggles

All over the Philippines and the Pacific you find variations of these unique dive equipment.
Most are made out of wood, but i also found low volume Epoxy versions and recently one awesome model made out of Water Buffalo Horn.
Most of the fisherman paint their wooden goggles to protect the wood and it has the nice side effect that one gets a better seal.
Since many of the people i showed the goggles really like the wooden feel i found this picture on the www ...

... that inspired me to make a Teak Wooden Goggles which seals good and looks awesome.

Teak wood is also the best choice for any water or saltwater use. Its extremely durable and requires very little maintenance.
All goggles are handmade by 2 Philippine fisherman.
Here you find some pics of the production.
http://www.facebook.com/woodengoggles/photos

The Glass
The glass in the above goggle is regular 3mm window glass.
It is NOT tempered (heat treated) to increase its strenght.
I short thought of doing this for safety reasons but then it would loose the whole sense of being a traditional piece of diving history.

BTW ... A bit THX to Dimitri for being part of the beta testers.

 

[wdaf]

Not good for open pool sessions during sunny day for me, I need tinted glasses!

Solution?!?
I found 3M window tinting foil that i could simply apply to the glass before it is glued in.
It also has UV protection.
Good Idea?

 

[dimitris33]

Yes man, 3M window tint foil was in my head too but havent found the time to do it yet!

 

[wdaf]

yes, you can ...

73.8m dive with wooden goggles.

[ame=http://www.youtube.com/watch?v=0Im_Cb-gosk]Manu Manu to the bottom of the sea - YouTube[/ame]

 

[Simos]

yes, you can ...

73.8m dive with wooden goggles.

Manu Manu to the bottom of the sea - YouTube

This is great/interesting for more reasons than just the goggles, thanks for sharing! Do you know if the goggles had flooded at some depth?

 

[dimitris33]

Per my experience, the goggles starts flooding at 6-7 meters. At -10meters are half filled. You feel no pressure all the way down.

 

[rovanpera]

The goggles these guys are using are very very small, they fit inside the eye socket.

 

[Simos]

Yes the only way is if they are either really small and/or partly (or fully) flooded. (thanks Dimitri and Jussi)

I guess the question is whether they offer any meaningful visibility at depth or whether they flood too much (guessing they do otherwise there would be no point)

Also even more intrigued about how they equalise. Must be some form of BTV (for those with intact ear drums) but again incredible that thy can do it for those depths. (admittedly head up makes a big difference)