[TDI] What training should I do for wrecks?

[Manatee Diver]

I'm still confused by what is "legally" allowed by the Trimix certifications though:

Advanced Nitrox + Deco Procedures = Can go to 45m but only with nitrox, no helium
Advanced Nitrox + Deco Procedures + Extended range = Can go to 55m but only with nitrox, no helium
Advanced Nitrox + Deco Procedures + Trimix = Can go to 45m with nitrox OR up to 60m but only with with helium ? (i.e. 50-55m on Nitrox not allowed?)

Well there is no scuba police, the limits are just for training. So you can typically do whatever you want if the operator is ok with it.

My personal limits:
Nitrox 30-40 meters depending on the nature of the dive.
21/35 - 50 meters
18/45 - 60 meters
Deeper than that, and my wallet would kill me if I did it OC.

 

[Jim Lapenta]

Wow, hot dropping sounds sketchy AF, I've always used a line for the wrecks I did.
Got it for depth, makes sense!

I'm still confused by what is "legally" allowed by the Trimix certifications though:

Advanced Nitrox + Deco Procedures = Can go to 45m but only with nitrox, no helium
Advanced Nitrox + Deco Procedures + Extended range = Can go to 55m but only with nitrox, no helium
Advanced Nitrox + Deco Procedures + Trimix = Can go to 45m with nitrox OR up to 60m but only with with helium ? (i.e. 50-55m on Nitrox not allowed?)

"Legally" you can do whatever you want. Is it a good idea? Probably not. Also the depth limits for the various certs are related to what you can do in training. Once you're done with that, you can decide how to work yourself up to greater depths/times/etc. One boat we dive from assumes you know what you're doing and all they ask is your run times and when they should assume you screwed up or had an issue and they need to call in the recovery ops. Look at the best mix for a 50-55m dive the deco involved. Best mix for 50m (165ft) dive at 1.3 is 22%. Basically air. Which is also going to add to the deco time and bring on narcosis for many people enough to be too risky.
Anything over 130 ft should seriously begin to consider adding helium to the mix. I tend to limit my dives to 120 or so without any and those can be managed with a helitrox class added to AN/DP.
Now, once you have the card, if you need it and can afford it, nothing wrong with a little helium on anything over 30m (100ft).

 

[Pyndle]

Thanks. Yeah I know there's no police/law, but most operators will check your license, as in if you want to do the wreck that is at 55m, you need to have a cert that says you're good to go to 55m. They probably wouldn't let me with my advanced nitrox + deco procedures (and rightfully so). Also the dive operations you describe seem lenient, all the tec dives I've done, they send a guide with me, and so they do have a say in the dive plan / gas mix. Never seen somewhere where you can just say "drop me and my buddy here with all our tanks, we'll be back in 70 minutes, we got this!". Also, insurance wouldn't cover me if my computer shows I went deeper than what I'm trained for.

Your answers pointed something I didn't seriously consider: narcosis. Never really felt it around 40m, I assumed I'd be fine at 50/55m (since the extended range theoretically allows you to do those dives without helium) but that's probably foolish of me. I also didn't really consider helium prices/availability....

I think for now I'll focus on doing both full cave and wreck training, and gaining experience in wrecks not deeper than 45m (both sidemount and backmount). Then I'll decide whether I need OC Trimix or go straight to Rebreather. I guess helitrox doesn't make much sense for me since I already have AN / DP, might as well go straight to the Trimix course (they're almost the same price).

 

[Ontwreckdiver]

Up here in the Great Lakes, the boat is just a taxi to the dive site. There aren't any DM's or guides in the water. You are expected to plan and execute your own dive.

 

[Dusty123]

I seem to recall a dive where you missed the Okinawa in only 70' of water. Oh wait, I missed it too. Let's just say the drop was not a good one!

But we barely missed it and made it to Qualman Tugs so they can be linked together!

 

[KenGordon]

Thanks. Yeah I know there's no police/law, but most operators will check your license, as in if you want to do the wreck that is at 55m, you need to have a cert that says you're good to go to 55m. They probably wouldn't let me with my advanced nitrox + deco procedures (and rightfully so). Also the dive operations you describe seem lenient, all the tec dives I've done, they send a guide with me, and so they do have a say in the dive plan / gas mix. Never seen somewhere where you can just say "drop me and my buddy here with all our tanks, we'll be back in 70 minutes, we got this!". Also, insurance wouldn't cover me if my computer shows I went deeper than what I'm trained for.

I dive in the U.K. where we don’t really have guides, let alone ‘Tec’ guides. You are totally responsible for yourselves. If you exhibit gross incompetence someone might ask if you are sure.

All my CCR courses had some helium element. The shops will still give me air fills for my dil.

Gas mix rules are really to stop people getting proper deep mixes before they are trained for the depth.

I think you might want to try the blind exit from a random collection of antique rusty beams and blown up plate with just a bit of string to get you home sooner rather than later. It might cause you to review your assumptions about gas duration.

 

[Fibonacci]

@Pyndle I've witnessed experienced and impressively qualified divers clang into the roof or sides of passageways and totally silt up their way through many a wreck over the years...

TBH I'd say the most immediately useful wreck training would be self guided!
1) Buoyancy control... practise being absolutely neutral at a given depth till its second nature;
2) Finning techniques... doesn't take much to kick up a lot of fine silt deep inside a wreck which will dramatically lower viz and may lead to disorientation... couple of fatalities on the subs here in Melbourne due to that;
3) Equipment... know your gear inside out and how to operate it in zero or near zero viz without getting flustered or panicked.

THEN you could look at a cave diving course, Trimix, CCR etc

 

[100days-a-year]

Wow, hot dropping sounds sketchy AF, I've always used a line for the wrecks I did.

Sounds sketchy, is sketchy but also sometimes the only option.
I did a lot of shallow wreck diving with the only penetration being obvious and very large swim throughs becore adding depth all the considerations it brings.
Doing a lot of easy wrecks with lots of time to see all the potential hazards as well as entry and exit strategies has never hurt anyone.
I think I like the Euro version of personal responsibility for dives rather than the nanny state " we're all gonna die!!! " philosophy here.

 

[Marie13]

Sounds sketchy, is sketchy but also sometimes the only option.
I did a lot of shallow wreck diving with the only penetration being obvious and very large swim throughs becore adding depth all the considerations it brings.
Doing a lot of easy wrecks with lots of time to see all the potential hazards as well as entry and exit strategies has never hurt anyone.
I think I like the Euro version of personal responsibility for dives rather than the nanny state " we're all gonna die!!! " philosophy here.

Great Lakes diving is about personal responsibility, as well. From what I’ve read NE and California diving seems similar. I think you need to get away from the tropics…

 

[happy-diver]

I've witnessed experienced and impressively qualified divers clang into the roof or sides of passageways and totally silt up their way through many a wreck over the years...

Any wonder when you are diving like this

Gotta get a backplate and wing, man

In the SG, which is on it's keel, in sidemount every hatch meant I had to stop, go sideways and recover. Workable but suboptimal.

I've been on the USS Samuel Gompers (AD-37) too

I have picked up divers as far a 2 miles away from the dive site due to long deco times and drifting in the Gulfstream during their stops. That is the most scary part of a hot drop.

Who needs the responsibility of being a captain