What do you look for in students to tell if they are ready for AN/DP?

[beester]

I'm currently teaching someone an IANTD adv rec trimix ticket which is basically the same as AN/DP but with trimix thrown in and a bit more depth (45m or 51 on the + cert).

Basics basics basics... being familiar with the gear you'll be diving with (doubleset, drysuit, etc), being able to do ascends (a lot of the practice will go into this in any case). Students coming in always focus too much on the new stuff... "how to plan deco", "how to do a gasswitch", "diving with a deco stage"... while their focus should be on the basics (trim, buoyancy, awareness, ascend practice).

The students I'm having now have done GUE fundies which is a major plus for me as an instructor... I've seen them in the water and they have the basics down! No time needed to waste on correcting any of that stuff.

The practical part will be focused not only on ascends, gas switching and deco, but also on how to handle oneself on a boat, keeping organised, how to efficiently setup, do a brief, equipment check... how to drop in the water, how to get to the buoy line swiming against current, equipment stress and how to handle it... that kind of stuff.

Wreckdiving you are always working against a clock (totally different with cave diving). When the charter captain says you need to be ready in 30 min, you need to be ready. That in my experience is a big shift for students coming into AN/DP.

And then there's the stuff underwater... blue water ascends are a thing... as is losing your ascend line (unless a drifting deco was agreed on of course).

PS: yes you can do an AN/DP course in a lake or pond, but what's the use, you are missing out on a lot of non dive curriculum that's important, so I totally follow Kensuf on this.

 

[Wibble]

I am curious as to why that is the case. I would think that it would be far safer and easier to have a visual and tactile reference such as an smb on a spool/reel etc. under which the drifting diver could "hang".

Is it good practice to have the smb for reference? Is the actual use of it for real deco required when training? Is it good to be able to not need one incase of an emergency?

I don't really know much about this, do a lot of people do blue water deco in a current without (using) this piece of gear? thanks?

"Real" dives (or at least the ones I do)…. It’s one SMB per diver so you’ll be putting up you bags together with your buddy. It’s best if you put both bags up within a few seconds of each other to minimise the pull of the current.

Send up the SMB from the wreck, generally from the top or a high point, checking there’s nothing to catch on (masts, etc). Spool or reel, the trick is to keep things tidy before and during the inflation. Keep the string short, hold on to the reel handle and be ready to press the release when the SMB shoots upwards — fail to do that and you’ll be looking to deploy your spare SMB when it’s dragged out of your hand. String or webbing catching on the reel handle is another bad thing.

Once the spool/reel is spinning try to put a little friction on the reel so it stops when the SMB breaks surface. Once it stops, wind the slack in. Once ready start your ascent to your first stop, keeping the slack wound in. Dump from your drysuit as you go and periodically dump from your wing/BCD — I prefer continual dumping a little from the suit with big dumps from the wing (because you can’t dump from the wing/BCD and wind a reel/spool at the same time).

Keep in control as you’re ascending. If you’ve a buddy you may need to adjust your ascent rates to match each other.

As you get closer to the stop slow down. When within a metre/3 feet settle yourself down and sort your buoyancy so you’re not heavy and hanging on the spool/reel to stop dropping.

Chill out. Use the time to tidy your kit, turn off torches, tuck away hoses or wires. Your buoyancy should be good enough to let go of the reel and hover beside it, although lightly holding the reel is fine. When that sop has cleared, slowly ascend to the next stop - it’s generally 3m/10' a minute which is quite slow, 30cm/one foot per six seconds.

More ascents means more practice. More practice means better ascents. Better ascents means easier and safer diving.

 

[divezonescuba]

I will take a different perspective on this.

While certain fundamental skills are necessary. I believe that the student also has to be mentally qualified. What I mean by that is that they have to understand that technical diving is more demanding than recreational diving and requires certain characteristics.

Some agencies say that the characteristics are being self-sufficient, team player, disciplined, cautious, physically fit, and will accept responsibility. I have also heard of humility as a desireable quality.

Sometimes, the students with the least potential are the ones that think they know it all. Many recreational divers think they know it all, but come to realize how little they really know at least with respect to technical diving. The Dunning-Kruger effect at its best.

Successful technical diving students come in with an open, receptive mind. The worst offenders are frequently recreational instructors. I know of some technical diving instructors that wont teach recreational instructors because of this issue.

 

[rjack321]

I am curious as to why that is the case. I would think that it would be far safer and easier to have a visual and tactile reference such as an smb on a spool/reel etc. under which the drifting diver could "hang".

You don't hang from it, you need to be neutrally buoyant

I don't really know much about this, do a lot of people do blue water deco in a current without (using) this piece of gear? thanks?

Not for very long if you expect the boat to 1) find you and 2) nor run over you and kill you with a prop strike.

 

[rjack321]

"Real" dives (or at least the ones I do)…. It’s one SMB per diver so you’ll be putting up you bags together with your buddy. It’s best if you put both bags up within a few seconds of each other to minimise the pull of the current.

The OP is in Alabama, it's one per buddy pair on this side of the pond.

 

[johndiver999]

You don't hang from it, you need to be neutrally buoyant

Not for very long if you expect the boat to 1) find you and 2) nor run over you and kill you with a prop strike.

Thanks, how do you "keep it up" without hanging from it?

 

[Jcp2]

Thanks, how do you "keep it up" without hanging from it?

Some people have a small weight attached. Others use the little blue pill.

 

[KenGordon]

I am curious as to why that is the case. I would think that it would be far safer and easier to have a visual and tactile reference such as an smb on a spool/reel etc. under which the drifting diver could "hang".

Is it good practice to have the smb for reference? Is the actual use of it for real deco required when training? Is it good to be able to not need one incase of an emergency?

I don't really know much about this, do a lot of people do blue water deco in a current without (using) this piece of gear? thanks?

For a sea boat dive it is essential the boat can find you. Typically for deco dives that means you must come up a shot line or on a DSMB since you will go a long way while doing the deco.

I never expect to have to do deco without a visual reference. I have a DSMB and a backup, so does my buddy. I think it would be quite hard work doing 30 minutes plus of deco with just a depth gauge to judge position, even with decent buoyancy control as required by ANDP.

Locally, some boats for some dives ask for one DSMB per diver.

 

[Wibble]

Thanks, how do you "keep it up" without hanging from it?

You don’t "keep it up" -- putting enough weight on the string to hoist the SMB vertically needs a fair amount of weight which you're not going to add to the reel unless you're literally hanging off of it. "Hanging" on the reel/spool is a really bad thing as you will be overweighted: you'll drop like a stone if the bag/string breaks, you'll probably be vertical (bad for decompression), it's lazy, you're not in control.

You are neutrally buoyant at your stop. You don't need to hang on to the reel/spool as you're drifting in the current just as fast as the SMB. The surface wind will slowly blow the SMB along so you may gently fin behind it (it's slow because of the drag of the string and reel).

Most importantly the reel/spool bobs up and down with the surface waves which you'll be unaware of at 6m/20' -- unless a storm has blown up! With larger waves the reel/spool will bob up and down a fair way, sometimes 2m/6' in bad conditions, or when a passing ship's wake runs through.

I tend to have the reel/spool set a couple of feet / 60cm below me and back off from it. Then there's a visual reference for your depth without watching your computer like a hawk. Actually you can sense through the pressure of your drysuit if you're ascending/descending.

If you've a long final stop it's almost zen-like where you can do what blokes like doing most... nothing. It's really calming like meditating as there's literally nothing you can do whilst you wait for your surface GF to drop to GF-hi. Personally I like that "me" time.


SMB sizing...

This has to be said. An SMB is useless if it's small or not properly inflated. The boat skipper/captain needs to be able to see and identify it on the surface within the field of drifting SMBs. A pathetic weedy little training SMB -- one of those 1m/3' things you fill with one breath -- has no place on a real dive. Those are training blobs purely for quarries. You need a thick and long one. Girth matters enormously as does length. Skinny ones are hard to see.

When you're inflating them on the bottom, it's much easier to completely fill the SMB when inflating deeper as the gas is at a higher intermediate pressure for the same amount of injection time. Thinking of the typical Halcyon et al SMBs with the inflator spigot which you connect your drysuit inflator hose to.

Big, in this case, is better.

It is massively easier to use a self-inflating SMB such as a 'crack bottle' or CO2 cylinder(s) to inflate it. My primary of choice is 2m/6'6" long and pretty thick, it's inflated with two 16g CO2 cartridges so is incredibly quick and simple to inflate -- especially on a rebreather where you don't have endless gas supplies.

The colour is orange or red. Yellow, in technical diving, is generally taken as an emergency signalling SMB, as you would have agreed with the boat in advance what you want them to do should you send up a second small yellow SMB up the string. Yes, advanced diving, but it might mean that you want them to send down your emergency deco cylinder from the boat.

On the surface...

When you've completed your final stop you will slowly ascend to the surface. 1m/3' per minute is often used as a guide.

Just before you leave your final stop you'll do a quick check of everything. Make sure your hoses are all neatly stowed away (if using multiple deco cylinders); make sure they're properly clipped off; tuck your umbilical torch cable in. Basically you don't want to look like a sack of *** when you surface, but most importantly you don't want to have hoses/cables/whatever catching on the boat as you climb out otherwise it's an expensive day.

Arriving on the surface you inflate your BCD/wing and close your drysuit dump. Then you hold on to the SMB and raise it vertically to let the boat see you're up. Then wait for them to come to you and pick you up. It's amazing on the surface just how noisy and horrible it is in comparison to the past hours(?) spent on the dive and at deco. Mayhem describes it nicely when the wind's picked up since you jumped in.

When the boat passes beside you, you will pass the SMB up to someone leaning over the side (another reason for a long SMB). Then you can get around to the stern to climb into the dive lift -- or ladder if you're in the US ; how quaint!

 

[Searcaigh]

Sidemount diving off of a boat seems like a pain I should probably avoid but I'm not certain yet.

A lot easier than a long walk on a shore dive.

Some SM divers in my neck of the woods hang the tanks off the boat and splash without them if there is no current, then hook everything up before descending.

Back when I dived with the BSAC Techies here, the rebreather guys usually hung their bail out bottles from the boats and attached them again on surfacing.

Splashing with a twinset and two small deco bottles (i.e. less than AL80 size) is no issue for me (170 cm / 68Kg)