Rebreathers and fast current

[spt29970]

Dolphins and whales herd fish using bubble curtains, presumably without all the noise our regulators make, so it is reasonable to believe that the bubbles themselves do scare the fish to some extent.

Why do you think that bubbles generated by dolphins and whales are silent? The bubbles themselves are the source of the noise, regardless of who generates them. You can verify this yourself with a simple test. Descend about about 5 feet in a swimming pool and breathe slowly. Wait for the bubbles from your last exhale to hit the surface, then notice that it is virtually silent while you are inhaling. As soon as you exhale again, it suddenly gets noisy. If you are down more than about 15 feet, the bubbles from each breathe don't have a chance to reach the surface by the time you take the next one, so there are always bubbles in the water column and the noise never stops.

 

[vladimir]

.....

 

[danvolker]

Danvolker that sound like a good idea but isn't it the bubbles that also scare the fish away or do you think it's mostly the sound.
Ian

The bubbles are what makes the sound...large bubbles make a lot of sound, little micro bubbles make almost no sound..... we are talking fireworks versus a tiny fiz

 

[Ianstephenzs]

Gill envy "Watching Pelagic freed on Swarms of fish with hours of gas to spare " sounds like you found heaven. Thanks for the informative post
Danvolker I guess what I was saying is it the visual aspect of the bubbles or is it the sound that that is made by the bubbles that scare the fish away.
Ian

 

[spt29970]

The bubbles are what makes the sound...large bubbles make a lot of sound, little micro bubbles make almost no sound..... we are talking fireworks versus a tiny fiz

That is a good point. The same volume of air distributed as a few large bubbles makes much more noise than lots of small ones. I like the idea of having a screen for open circuit that breaks up the big bubbles.

 

[danvolker]

Danv,

There are a few very tangible advantages to a breather; I can dive the whole weekend, let's say 5 dives at any desired depth on less than 13 cf of O2 and about 15 cf of diluent. The diluent can be anything I want it to be from nitrox to trimix. Cost is not that big.

I can do all these dives without disassembly / re-assembly of the unit. I never get cotton mouth. The gas is above ambient unlike OC scuba so I retain more body heat.

It is is not all about noise, though I do like the critters getting in closer.

To be sure there are some drawbacks but the task loading, at least with an MCCR is not that great. Initial cost really depends on what you buy, but I have seen some very expensive OC rigs that cost more than my unit! Mod 8 BTW, whilst my unit is weighted for an 1/8 in suit, it ways about the same as a normal OC setup.

I do like your idea on quiet OC diving, but all those tanks being hauled to and from the dive site just makes me tired.

Dale

Dale,
Some of my best friends are rebreather divers
I am not trying to talk badly about rebreathers....I am also sure you will agree that rebreathers are not for "everybody".
I do personally believe you should have some kind of a reason for using a rebreather beyond just because they look cool. Most of the people on this forum will certainly have those good reasons....
The OP made an honest request of information and ideas, but sounded more like a candidate for open circuit...at least to me....

 

[bletso]

I definitely agree, rebreathers are not for everyone just as tech or cave diving. It is hard to see that the way all the diving rags and agencies try to push these really advanced and higher risk ventures.

Safe Diving,

Dale

 

[Ianstephenzs]

Back to the the topic before this turns in to something about who should be allowed to use a rebreather. I think it's is the visual aspect of the bubbles that plays the biggest part in scaring fish off.
Ian

 

[danvolker]

Back to the the topic before this turns in to something about who should be allowed to use a rebreather. I think it's is the visual aspect of the bubbles that plays the biggest part in scaring fish off.
Ian

Maybe, but you know all fish have a lateral line that works far more effectively for them ... to alert of sudden movements/vibrations, injured fish, attacking fish, etc, than does our sight underwater---so I am thinking the hear or "feel" the bubbles....the large bubbles could be at a frequency that is particularly disturbing, and the little fiz like bubbles may not make enough of a vibration in the water to create much of a sound wave--or the frequency may be of a tone that they ignore ( I have seen how the early Kellon filters worked, and the fish had zero reaction to this, when compared to open circuit).

 

[Mr.X]

Where is Jack Kellon these days?
Thanks.

X

p.s. Also to the OP - diving a CCR, or MCCR in current and changing depth takes experience. Very easy to get a good knockout "kabong" when you use a RB in tough conditions. Slow and easy is the game. Getting a good noggin knock deep inside a cave, or wreck makes for a very crappy day.