Snorkel Hydrodynamics?

[Akimbo]

I have been studying in prep for a PFI course and was contemplating snorkels. I appreciate the value of spitting the snorkel out before breaking the surface. It seems that the technique I see most often is to spit the mouthpiece out just after leaving the surface. So, here are my questions:

1. Wouldn't a rigid J snorkel have better hydrodynamics when left in your mouth until just before breaking the surface?

2. If there is a functional argument favoring spitting it out just after leaving the surface, then wouldn’t a flex snorkel offer less hydrodynamic resistance?

3. Wouldn't exhalation resistance on a well designed snorkel with a purge valve be lower then a rigid J?

4. Does a simple rigid J have measurably different inhalation resistance than on a flex snorkel?

I have been using rigid snorkels for freediving and flex snorkels for Scuba most of my life. Thinking back on it, I am not sure I can tell any difference in breathing or hydrodynamics.

[ApneaAddict]

I don't know about hydrodynamics, but I can tell you that the reason PFI teaches that you should spit your snorkel at the beginning of your dive is because were you to black out, a snorkel in the mouth would provide a direct line for sea water to enter your lungs, complicating your rescue by about 10 fold. If you black out with your mouth shut, your mouth generally remains shut and a good dive buddy will grab you and have you on the surface quickly and within seconds you'll come to and never know anything went wrong with your dive. If that snorkel is in your mouth though, chances are you'll have sea water in your lungs and you'll need to make a bee-line to the nearest hospital (ruining your day).

I think the idea behind the j-style snorkel is the "keep it simple, stupid" principle. With a J snorkel, nothing is ever going to go wrong with it. It may not be a as dry or as high-tech or whatever else, but you know what you've got and you never need to worry about a malfunction or anything of that sort. Flex vs. rigid doesn't make much difference IMHO. I don't think PFI suggests one over the other, either. Flex is nice because you can throw it around and never need to worry about it cracking. But as I said, I don't think there's much difference beyond that.

The way the instructors for PFI will teach you to dive is actually to do you calming breaths, your purges, do your max inhalation (plus any packs you might want to do), then to remove the snorkel from your mouth, pre-clear your ears, and descend. That way your entry is smooth, silent, and efficient. When you're headed toward back up, you exhale when you're <6ft from the surface so that as soon as you hit the surface, you can do your hook and recovery breaths.

If you're about to take the course, though, you might as well wait with all these question and direct them to your instructors. They're very knowledgeable and helpful. Actually, I bet you could call and they'd give you all kinds of info over the phone. Erin (the instructor who also runs their office) is awesome and I'm sure could help you pick out a new snorkel if thats what you're looking to do.

[Akimbo]

Originally Posted by ApneaAddict

I don't know about hydrodynamics, but I can tell you that the reason PFI teaches that you should spit your snorkel at the beginning of your dive is because were you to black out, a snorkel in the mouth would provide a direct line for sea water to enter your lungs…

Excepted. What about spitting it our on the bottom for better hydrodynamics on the down trip?

Originally Posted by ApneaAddict

...If you're about to take the course, though, you might as well wait with all these question and direct them to your instructors. They're very knowledgeable and helpful. ...

Thanks for the reply. I was sort of hoping PFI would also reply since they are on this forum. I figured I wasn't the only person who could benefit from the discussion.

[ApneaAddict]

Originally Posted by Akimbo

Excepted. What about spitting it our on the bottom for better hydrodynamics on the down trip?

Honestly, I think the effect your snorkel has on your hydrodynamics is so minimal that spitting it on the surface is more beneficial to your overall dive profile because it's one less thing to think about throughout the dive. Unless you're looking to set a new world record, I don't think the drag of your snorkel would even register in comparison to all the other things affecting you (proper head/arm/hand position, proper fin kick-cycles, leg strength, weighting).

When I used to use a fancy purge-style snorkel, I did have trouble with it kinda flapping against the side of my head when I descended or ascended quickly. I don't know whether its hydrodynamics or just the way the snorkel sits on my head now, but switching to a J-style and spitting it before each dive fixed that problem.

Originally Posted by Akimbo

Thanks for the reply. I was sort of hoping PFI would also reply since they are on this forum. I figured I wasn't the only person who could benefit from the discussion.

Valid. They may have an account, but I don't think they're very active here.



For example, here: YouTube- Freedive training The diver clears his snorkel and descends with the form they teach in PFI.

[Akimbo]

Originally Posted by ApneaAddict

… When I used to use a fancy purge-style snorkel, I did have trouble with it kinda flapping against the side of my head when I descended or ascended quickly. I don't know whether its hydrodynamics or just the way the snorkel sits on my head now, but switching to a J-style and spitting it before each dive fixed that problem. ...

Yeah, some of the dry and semi-dry snorkels are HUGE — like what were they thinking??? I noticed that Riffe's Stable snorkel is relatively compact and might make sense. I figured if we are going to optimize masks and fins, why not snorkels?

Thanks for the insights.

[Gerald C. Perry]

Just a simple snorkel works best. I think it's so funny to see all these fancy snorkels with all this crap on it. I've seen one that looks like a bird feeder.

[O2 Deprived]

Erin or Ted in the PFI office will tell you to bring a simple "J" snorkel like a Riffe Stable or similar, a low volume mask , fins. wetsuit, weightbelt.
As far as hydrodynamics go- on the last day of diving when you go for a maximum effort dive ( 100ft+) I would either breathe-up upright or on your back without a snorkel or hand the snorkel to the safety/instructor before your descent. You don't need to drag that snorkel down with you on a deep dive. This max effort dive is different/deeper than a normal hunting drop so you can do it like a freediver does- no snorkel. Watch some of the videos of deep dives- no one has a snorkel.

[Akimbo]

Originally Posted by O2 Deprived

Erin or Ted in the PFI office will tell you to bring a simple "J" snorkel like a Riffe Stable or similar, a low volume mask , fins. wetsuit, weightbelt.
As far as hydrodynamics go- on the last day of diving when you go for a maximum effort dive ( 100ft+) I would either breathe-up upright or on your back without a snorkel or hand the snorkel to the safety/instructor before your descent. You don't need to drag that snorkel down with you on a deep dive. This max effort dive is different/deeper than a normal hunting drop so you can do it like a freediver does- no snorkel. Watch some of the videos of deep dives- no one has a snorkel.

I am less concerned over the deep dive in the class than normal freedive hunting. There seams to be a lot of effort to optimize hydrodynamics and a "J" snorkel out of your mount is not very good. I use an Omer Zoom (simple "J") now, but have been switching to an AquaLung Impulse 3 Flex when seas get sloppier. The more I use it, the less drag I am noticing compared to the Omer I normally use — but the difference is small enough it may be a phantom.

BTW: The Riffe Stable is a semi-dry with a purge valve and flex hose, as is the AquaLung Impulse 3 Flex. The other Riffe snorkel is just named the "Standard J". I have been thinking that if Riffe makes a snorkel like the Stable it is worth analyzing.

[Spearchuckerz]

We learned from diving with Martin Stepanek, that his snorkel is attached to the mask at the very back of his head.

When you spit out the snorkel before a dive it hooks under your neck instead of slapping on the side of your face. I do not use a snorkel keeper, so I just tuck the snorkel under my mask at the back of my head.

I also noticed their mask straps are higher on the back of the head instead of the center of the head most use.

When there are rough seas, this method does not work as well, due to the height of the snorkel in relation to the water.

Give it a shot.

[H2O ADDICTION]

This snorkel looks pretty "hydrodynamic" - for surface swimming anyways!

http://www.funswimshop.com/finis-fre...kel-2973-p.asp