Tech expectations

[Bazzathemammoth]

I envy you, 50m or shallower is the happy place. Crank up the O2 and there’s not a dive you can’t make on backgas twins.

That’s what I have been wondering, thanks for posting. I’m not sure that I’ll go the rebreather route long term as it seems like a lot of hassle and cost. I think my personal narcosis limit will be my max depth on air, possibly around 45m. I’m definitely narked below 30 but I think I’m safe enough at 40m. I need more experience tbh. I’m not sure how much more impaired I’ll get deeper down.

Thanks for the replies in general too. They have been helpful.

 

[AJ]

That’s what I have been wondering, thanks for posting. I’m not sure that I’ll go the rebreather route long term as it seems like a lot of hassle and cost. I think my personal narcosis limit will be my max depth on air, possibly around 45m. I’m definitely narked below 30 but I think I’m safe enough at 40m. I need more experience tbh. I’m not sure how much more impaired I’ll get deeper down.

I thought I did not have to much of an issue with narcosis until I did my first 50 meter dive with trimix 18/45. Then I realized how much narcosis affected me. Nowadays I do not dive below 30m without trimix.

The problem here is that you don't know what you don't know.

 

[Wibble]

Some years ago, when the UK had an 80m/260ft deep diving quarry, they had a little blue boat at 50m/165ft. For our second dive of the day, we'd air top off our 32% twinsets to get about 25% and we decided to drop down to the little blue boat to try out some narcosis.

Jump in and literally follow the vertical wall downwards. The water was pretty clear, so you could see the little blue boat from about 20m/60ft. My friend managed to get to the boat; I only managed to get near it at about 45m/150ft.

I was off my face with narcosis. Constantly checking my pressure gauge, my computer, then forgetting what I read on the pressure gauge and re-reading it, checking the computer... My face felt "tight" and it was pretty horrid.

Friend and I then ascended to the 28m/95ft bottom of the shallow end and hung there for a couple of minutes for the narcosis to subside, then had a perfectly normal dive swimming through the double-decker bus, the aeroplane, the tanks, etc., etc.

OK, dropping straight down to depth brings the narcosis on like a steam train because you go from no-narc to off your face in a minute, so you really notice it. However, if you slowly descend you don't tend to notice the "narcosis shock" as you've slowly adapted. Think of the poor little boiled frog that didn't jump out of the pan.

Definitely recommend people trying this in a benign location just for the reminder that narcosis is real.

A while later I did a boat dive where the target was changed from about 35m/115ft to 42m/135ft which actually turned out to be 50m/165ft on the bottom and 45m/150ft to the deck of the wreck. Had to dump a load of nitrox 32% to drop it down to 28% -- wrong for the final depth.

Nice dive, but first time I'd seen the High PPO2 warning on OC. Was off my face with narcosis and ended up mooching around the deck talking to the lobsters and blennies; "how are you today Mr Blennie...?". Don't remember much else though!

Guess what gas I had for deco... Of course it was the one time I brought 100% rather than my normal 80%. So I then saw the high CNS warning too. Dive ended well, just like any other dive really, although my chest felt like I'd been smoking!

I like helium on a rebreather. Life's so much clearer.

 

[Celt]

That’s what I have been wondering, thanks for posting. I’m not sure that I’ll go the rebreather route long term as it seems like a lot of hassle and cost. I think my personal narcosis limit will be my max depth on air, possibly around 45m. I’m definitely narked below 30 but I think I’m safe enough at 40m. I need more experience tbh. I’m not sure how much more impaired I’ll get deeper down.

Thanks for the replies in general too. They have been helpful.

Start off slowly, make a slow descent to your max planned depth for 5 minutes and slowly move up the wreck getting shallower as the dive goes on, In good vis you can hang around over the wreck and if you feel like it go a little deeper for a short time just to get used to it,there’s no rush often with wrecks sitting upright on their keel there’s nothing to see deep.

 

[Angelo Farina]

That’s what I have been wondering, thanks for posting. I’m not sure that I’ll go the rebreather route long term as it seems like a lot of hassle and cost. I think my personal narcosis limit will be my max depth on air, possibly around 45m. I’m definitely narked below 30 but I think I’m safe enough at 40m. I need more experience tbh. I’m not sure how much more impaired I’ll get deeper down.

Thanks for the replies in general too. They have been helpful.

You will get accustomed to narcosis and it will disappear after a few consecutive dives at increasing depth. After one year break I also get narched at just 30m. But in 3-4 days I can progressively reach 50m, and after that, if diving every day at 45-50m, everything is Ok.
If you take a break of one or two weeks, you loose part of this resilience.
Narcosis depends on a number of factors. Health conditions, hydratation, depth, water temperature, sunny or cloudy sky. And the most important, CO2 retention. If you overstress and do not breath properly, CO2 will accumate and trigger a strong narcosis, and you will get a back-head pain which will last hours after the dive.