Fist time I called a dive at depth...

[Bretagne]

Reread the original post Derek, they were NOT students in a class and they were NOT with an instructor. But I doubt very seriously if her husband even thought about grabing her BC, the DM did that as a precaution. If diving by themselves they would have just ascended after calling the dive.

Had we be alone (if I have had a problem in a 20m dive), my husband would have grabed my BC because we have learned that it is the first thing to do when someone requires assistance (if it is not needed, you let go afterwards). We have both had dozens of pool sessions to get this kind of automatisms.
We were not students and not with an instructor, true. But our rating says that we are able to handle ourself at these depth (including to recognise a problem and signal it) but not to assist some one who has a problem, hence the necessity of a N4.

 

[Bretagne]

The law may not be literal law but I think it has too do with insurance and rescue costs.

The law is litteral if we dive in an organised structure (club or dive shop), not if we go completely bu ourselves.
Globally, the laws means that in a group, at least one people (and in some cases every one) is able to uplift the others. N2 (P**) we are able to uplift someone of same rating from 20m, N3 (~P***-) is able to uplift some one of same rating from 40m, N4 (=P***) is able to uplift someone of lower rating -more risk of panick- from 40m.

 

[eponym]

Salut, Bretagne

Thank you for the clear and detailed account. Good to know you completed the dive safely.

I too sometimes forget to check my venturi control, only to find at the end of a dive that I've been breathing it the hard way. Fortunately, I don't feel a lot of resistance that way (on my Titan LX) so it doesn't make a problem for me.

when you go down fast, be careful that it is because you swim down, and not because you are negatively buoyant (I realised that it is not always obvious to feel, especially when you concentrate on something else at the same time)

Well said, and a good thing to learn. When I'm descending, especially in low visibility, I keep adding small puffs of air to my BC and monitoring my descent speed with my depth gauge. I want to be able to stop or ascend at any moment.

I took the DAN seminar on ears and diving, which gave me some great information on how my ears work and how clearing them works. Now I try to clear my ears on every breath while descending. It's made a big difference for me, and made it much more of an automatic habit.

A bientôt,
Bryan St.Germain

PS: Diving the channel sounds challenging--I learned to sail there, many years ago. I'm impressed.

 

[Diver0001]

What is the method to send a shot line which do not drift when the boat is not anchored? I am curious. It is true that the descent without reference was part of the problem.

Well one simple thing you can do is to throw a small anchor/grapnel with +/- 20kg bouy on it. You may have to get someone to go down first and "set" it either on a bottom feature or by using a screw shaped mud hook so it doesn't drift. For example the D4 could descend first (with a buddy if that's your procedure) and set the anchor at whatever depth you need and then wait for you and your buddy to arrive.....

There are lots of variations possible on this depending on how complicated you want to get with your logistics.

R..

 

[Bretagne]

Well one simple thing you can do is to throw a small anchor/grapnel with +/- 20kg bouy on it. You may have to get someone to go down first and "set" it either on a bottom feature or by using a screw shaped mud hook so it doesn't drift. For example the D4 could descend first (with a buddy if that's your procedure) and set the anchor at whatever depth you need and then wait for you and your buddy to arrive.....

There are lots of variations possible on this depending on how complicated you want to get with your logistics.

R..

From a zodiac, logistic must be very simple... Your proposal is completely opposed to all our diving rules, or it would have meant a group of 2 who dived only to set the anchor. Our rules are: the group stays together in all circumstances. Nobody dives to 28m then waits for the others.

 

[Bretagne]

PS: Diving the channel sounds challenging--I learned to sail there, many years ago. I'm impressed.

Probably not more challenging than Oregon's Pacific... There are probably a lot of similarities, as we are in a kelp area too.
The place were I dive has a lot of well protected diving sites. And more exposed ones, too. It is cold, but April to october, a thick wetsuit is enough. DM and other instructors usually use semi-dry.

 

[Diver0001]

From a zodiac, logistic must be very simple... Your proposal is completely opposed to all our diving rules, or it would have meant a group of 2 who dived only to set the anchor. Our rules are: the group stays together in all circumstances. Nobody dives to 28m then waits for the others.

You mean you are you not allowed to make a decent along a shotline without the D4 supervising? I thought 2-star divers were allowed to do that. Does it have to do with the depth? Maybe starting shallower would be the solution.

I suppose you could use someone especially to set the anchor but my first instinct in that situation would be to use a heavy enough anchor that it didn't need to be set.

R..

 

[divenut2001]

I do not need less weight at depth, but I need more weight for my safety stop when I have dived shallow, otherwise I rocket to surface. And I do not like polaris missiles.

"YOU" said in your OP that you forgot that you needed "less" weight when you're diving deep. WRONG!!!

You need to add more air to your BC the deeper you go and then let it out as you ascend. When you're doing your safety stop you should be able to hover @ 15ft with "NO AIR" in your BC.

If you can't stay down then "YES", "ADD" some weight.

If you sink then "YES" you can "DROP" some weight.

When you can hover @ 15ft with a near empty tank and "NO" air in your BC you'll be "properly" weighted and find diving a whole lot easier, ie...Being able to control your buoyancy with your lungs instead of your BC...Less air consumption... Not having to work as hard...Less stress...etc...etc...etc...

 

[Bretagne]

Exactly what I say. To be neutral with no air in my BC at the safety stop, I need less weight when my dive has been deep than when my dive has been shallow. I have no explanation, except that may be the decompression of my wet suit is slow, and it is not fully decompressed when I come back from a deep dive. Difference is small, may be 1kg.
Diver0001, no, we are not allowed to go deeper than 20m without a N4, even with a shot line. And even more, the boat didn't want to anchor to be able to retrieve quickly the other groups of divers. You must consider this as a drift dive, even if it is not really that because the flow is a lot slower at depth.

 

[Diver0001]

....snip....

Diver0001, no, we are not allowed to go deeper than 20m without a N4, even with a shot line. And even more, the boat didn't want to anchor to be able to retrieve quickly the other groups of divers. You must consider this as a drift dive, even if it is not really that because the flow is a lot slower at depth.

Hi,

I've been thinking about this. It sounds to me like you're trying to make the descent too deep. If you're not supposed to make a descent to more than 20 metres without supervision then making one to almost 30 without a reference isn't a good idea. I think you should make your descent to 18 metres and work down along the bottom from there. Maybe this can be done without a reference but I still think that rigging a shotline is possible and a good idea.

In terms of setting the shotline you don't want to have a dedicated team to do that and (this is the part I've been thinking about) you don't want to have to use too big of an anchor.

My idea is to still use a 20 kg float but instead of a grapnel use a 10kg anchor. You can rig it as follows: Under the float hang a long line, almost twice the length to the bottom, along a series of rings or caribiners, using a weight like maybe a couple of 2 kg scuba weights to keep the line straight enough to use as a reference. That way the anchor will stay on the bottom even if the float get lifted by a wave (ie, you don't need to set it) and you'll have your reference for descending. You'd have to remember to grab both parts of rope if you needed to hang from the float but this is a workable solution for a zodiac as long as the surface current isn't ripping.

I don't know if you can follow what I mean from my description so PM me with your email address if you want me to draw you a picture of what I mean. If you're not interested we'll leave it at that.

One word of disclaimer. I'm sure I could get this to work but it may take a little refinement.

R..