Some newbie questions...

[Sagara]

Hi folks, I just recently went snorkeling for the first time, and I had some questions about recreational free diving. I don't really approach this as any sort of discipline or competition, I just want to have fun in the water and not hurt myself.

So, anyway, I love diving down and once I got used to the snorkeling I was going down to the bottom where we were, which was somewhat under 20 feet, mabe 25 ft or so is my estimate. I love diving down and feeling like I am one of the fishes and I want to do that a lot more and deeper.

Questions:

1) At what depth do you have to start worrying about pressures and compression and that sort of stuff, in other words at what depth is it not just plain old swimming anymore?

2) What would happen if the pressure when you are diving caused your mask to collapse? Is this even possible [assuming one breathes into the mask a little to equalise the pressures]? [Assume you are using cheap gear.]

3) How long should one expect to be able to dive compared to how long one can hold one's breath on the surface without any physical exertion? Assuming, for instance, 33% of the time is spent diving down, 33% is spent swimming at depth, and 33% is spent coming up. If I can hold my breath comfortably for two minutes, should I expect to be able to dive for that long?

4) Why are low volume masks better for free diving?

5) Is there any risk of getting "the bends" from an ascent after a free dive? Say you go down 100ft, can you just come back up as quickly as possible, or do you need to do it gradually? At what depth does one have to begin to worry about this?

6) Sharks -- is it just a matter of crossing your fingers and trust the good odds they will leave you alone, or is there something that one does in order not to appear as bait?

7) Fog -- how do you guys keep your mask from fogging up, and if it does fog up is there anything you can do about it out on the water?

Erm, I know there are a couple I am forgetting, but I guess that is enough already! Thanks for any help!

 

[laminar]

Hi Sagara,
I'm sure you'll have more questions, so a search of the forums on different topics will bring up some interesting and helpful information and discussions.

Questions:

1) At what depth do you have to start worrying about pressures and compression and that sort of stuff, in other words at what depth is it not just plain old swimming anymore?

Swimming is on the surface, anytime you go down beneath it and equalize you are freediving!

2) What would happen if the pressure when you are diving caused your mask to collapse? Is this even possible [assuming one breathes into the mask a little to equalise the pressures]? [Assume you are using cheap gear.]

Your eyes will hurt. If you ignore the feeling then the cappiliaries in your eyes will bleed. It's called mask squeeze. So as you go down, you'll need to exhale/push air through your nose to equalize/repressurize the mask.

3) How long should one expect to be able to dive compared to how long one can hold one's breath on the surface without any physical exertion? Assuming, for instance, 33% of the time is spent diving down, 33% is spent swimming at depth, and 33% is spent coming up. If I can hold my breath comfortably for two minutes, should I expect to be able to dive for that long?

There are no set rules for time underwater. And the correlation with dry or wet static breath holds is not clear. You'll figure out over time what yours is. Start from scratch underwater and have someone watching you (see our forums about blackout and buddy systems). It is pretty important when you're starting out and experimenting to do it with someone else and have a safety plan. And it's more fun that way!

4) Why are low volume masks better for free diving?

They have lower volume, so that means it takes less air from your lungs to equalize the mask as you go deeper. Saves you oxygen!

5) Is there any risk of getting "the bends" from an ascent after a free dive? Say you go down 100ft, can you just come back up as quickly as possible, or do you need to do it gradually? At what depth does one have to begin to worry about this?

In theory there is a risk of getting the bends. There's a lot of difference in opinion on this but top freedivers do decompression on pure oxygen after really deep dives. Some will slow down in the last 30 feet of their ascent. Others sprint to the surface. But the risk is probably a lot more reduced than in scuba diving. In my general opinion, if you ascend slower than 3 ft per second, you should be okay, but understand that the bends is very complicated and different for each individual. I expect there will be more research on this in the future.

6) Sharks -- is it just a matter of crossing your fingers and trust the good odds they will leave you alone, or is there something that one does in order not to appear as bait?

Depends where you dive!

7) Fog -- how do you guys keep your mask from fogging up, and if it does fog up is there anything you can do about it out on the water?

Wet you mask with water. Spit on the inside of the lenses. Use your fingers to spread it around. Rinse it out. Repeat as needed. That works for most people. Plastic masks fog more easily, though.
Have fun!
Pete

 

[Sagara]

Hey, thanks a lot, bro.

I read somewhere that one should try to keep the inside of your mask as dry as possible in order to prevent fog, but you seem to be saying the opposite? Or are you just talking about what to do after the mask is already fogged up?

 

[SanderP]

A good way to prevent your mask to fog up is to clean it before your dive. Use whatever you want (toothpaste, dish-washing liquid...) and make sure the lens is totally clean, so if you look at it through light, no spots are visible (and if you rinse it with water, no drops stay on the lenses).