Snorkel cracking pressure?

[John C. Ratliff]

Tusa Hyperdry doesn't seem to restrict my breathing any more than a J-snorkel. Really dry. I've ended up with a bunch of them because they come with the mask, which is my favorite.

The TUSA HyperDry snorkel is one of the better snorkels, but it does have resistance built into it. The end piece, along with the curve of the ent of the tube, are designed to keep water from waves out, but also provide just enough resistance that with a sharp exhalation water can be cleared out of the bottom of the snorkel. I used mine in the pool today, and Imdo enjoy it.

I also have the TUSA (for Tabata USA) HyperDry Imprex mask, which I like a lot. I bought it for my wife in the late 1990s, but now that she has a new mask, I inherited it from her. The only down-side to this mask is that the mask is clear silicone, and I see the strap knuckle system as a black dot to the side of my vision on each side. I really like the purge valve on the front of the mask, and the fact that it can be removed for cleaning. It is number 3 in the photo. Below.

SeaRat

 

[MAKO Spearguns]

I use the Mako snorkel I got from www.MakoSpearGuns.com :

View attachment 559843​

It's a no-nonsense snorkel that's plenty dry after you clear it.

Thanks for the mention and positive feedback Pete!

Our current model of snorkel is slightly different now, but is remains a simple and comfortable breathing tube. We have evaluated many snorkels with various "dry" and purge features and noticed that some snorkels provide too much breathing resistance.

https://www.makospearguns.com/Freedive-Snorkel-p/mfsnkl.htm

 

[The Chairman]

Thanks for the mention and positive feedback Pete!

You've earned it! Well, it earned it. I can't count how many snorkels I've picked up off the bottom of the ocean. Living in the Keys for eight years allowed me to gather quite a few. They're probably "OK" for the rare times I used them, but when I started doing a lot more freediving, I went with a classic. They're pretty inexpensive, too. I like how it's designed to go around the back of your head.

 

[Nemrod]

With double hose regulators they tell us breathing resistance depends on the level of the second stage (now behind your back) and your lungs. They hang their tanks very low so the yoke (and regulator) is centered between the shoulder blades.

A snorkel might be considered somewhat like a double hose regulator except that a double hose regulator has a 1) powerful Venturi (at least the good ones do) effect which the snorkel does not then continuing with the comparison but with single hose regulators instead, and 2) a very large diaphragm diameter/area to help overcome the pressure differential and as well, typically, 3) a lower cracking effort than a single hose regulator.

Before snorkels got fancy, there was the Scubapro Shotgun snorkel which was just a large diameter (bore) and rather short tube slightly curved to remain close to the head, these types, a simple tube, open ended, of large diameter and fairly short (to reduce rebreathed air) are still the most efficient.

N

 

[David Wilson]

There are national and international standards prescribing different dimensions for adult and children's snorkels:

Snorkel (swimming) - Wikipedia
The latest (2015) European Standard EN 1972 recommends choosing a snorkel with a maximum total length of 350 mm and a maximum total inner volume of 150 cc for users with smaller lung capacity, which includes children. Users with larger lung capacity, which includes adults, are recommended to select a snorkel with a maximum total length of 380 mm and a maximum total inner volume of 230 cc. Over time in national and international snorkel standards, maximum tube length has almost halved (from 600 to 380 mm) while maximum bore (inner diameter) has increased (from 18 to 25 mm).

 

[John C. Ratliff]

Thanks David,

I was hoping you'd say something here. I have not got your slide in my Photos on my computer. I had lost that one for quite a while.

Now, the AMF Voit snorkel I mentioned in one link above is a smaller diameter than the others. To my surprise, it was entirely adequate for my breathing even on a fast snorkel, and cleared very easily.

SeaRat

 

[John C. Ratliff]

Your windpipe is only about 25mm wide or a bit less than an inch. Friction of the air in the snorkel tube only matters if you're breathing really, really hard through it. Snorkels are great for looking at stuff before you dive down to have a closer look. Many freedivers, breathe really hard with the snorkel out of their mouths (or not even there) before they dive and don't return to the snorkel until their breathing is back to normal.

One of the big advantages of using the snorkel is that you constantly monitor the underwater world. Whenever you spit out the snorkel and breath with the mouth out of the water, you break visual contact with what's below.

I realize that committed free divers don't use a snorkel, and/or spit it out when going underwater. But these are guys and gals who are trying to maximize their underwater time and are usually going for depth too, sometimes in competitions. They really are not too interested in observing the underwater world, but rather are concentrating on their own physiological response to the dive and the depth.

In contrast a spearfisher or an underwater photographer/videographer wants to know at all times what's happening around him or her. This I see especially important if there are sharks, barracuda, large grouper, seals or sea lions around. Sometimes snorkeling, which is much quieter than open circuit Scuba, is the only way to observe certain animals, and the snorkel is fundamental equipment for these enterprises.

SeaRat

 

[BRT]

The TUSA HyperDry snorkel is one of the better snorkels, but it does have resistance built into it. The end piece, along with the curve of the ent of the tube, are designed to keep water from waves out, but also provide just enough resistance that with a sharp exhalation water can be cleared out of the bottom of the snorkel. I used mine in the pool today, and Imdo enjoy it.

I also have the TUSA (for Tabata USA) HyperDry Imprex mask, which I like a lot. I bought it for my wife in the late 1990s, but now that she has a new mask, I inherited it from her. The only down-side to this mask is that the mask is clear silicone, and I see the strap knuckle system as a black dot to the side of my vision on each side. I really like the purge valve on the front of the mask, and the fact that it can be removed for cleaning. It is number 3 in the photo. Below.

SeaRat

Yep. great mask. All we use. But not politically correct on Scubaboard. Have you noticed that you can buy the mask with the snorkel on Amazon and other places cheaper than the mask alone? That is why I have a collection of the snorkels. The mask is available in black and other colors.

 

[dmaziuk]

I realize that committed free divers don't use a snorkel, and/or spit it out when going underwater. But these are guys and gals who are trying to maximize their underwater time and are usually going for depth too, sometimes in competitions. They really are not too interested in observing the underwater world, but rather are concentrating on their own physiological response to the dive and the depth.

There's something about having your mouth closed, as I recall, but also it will simply pull your mask off to the side. Or at least make it leak, if you move any faster than a snail on tranqs. Even my oval-bore with no big bulbs on top does it. That's why swimmers use front-mounted ones.

 

[John C. Ratliff]

There's something about having your mouth closed, as I recall, but also it will simply pull your mask off to the side. Or at least make it leak, if you move any faster than a snail on tranqs. Even my oval-bore with no big bulbs on top does it. That's why swimmers use front-mounted ones.

Yes, the front-mount snorkel has its advantages, and is used exclusively in finswimming competitions on the surface. They are very streamlined, and allow very good clearing of the snorkel with the purge valve at the bottom of the tube.

I was Finswimming Director for the Underwater Society of America in the late 1980s and 1990s, and tried to re-introduce this sport to the U.S.A. To do that, I did participate in a few competitions, although my home-made monofin really caused an embarrassment when my feet slipped out of the fin upon diving, and rather than a swim I made a tumble off the blocks. That was before any commercially-made monofin was available. Here's a photo of me in the Roseburg, Oregon YMCA pool with a front-mount snorkel (sans purge valve) in about 1994.

John Finswimming by John Ratliff, on Flickr

Here is a finswimmer ready for a competitive dive (drawing):

Finswimming Snorkel001 by John Ratliff, on Flickr

Because finswimming as a competitive sport had not been commercialized, we had this diagram of how to shape a front
mount snorkel to the finswimmer's head. First, the plastic tube needed to be filled with sand, then heated, then formed around the head form of wood.

Finswimming Snorkel002 by John Ratliff, on Flickr

But, I have had side-mounted snorkels that have not affected my mask for flooding. I think it depends upon what mask is chosen, and how tight the strap in on the mask around the head. I have had side-mount snorkels in fairly high currents in Oregon rivers without problems.

SeaRat