My AN/DP/Helitrox course

[Marie13]

You can't take a Fundies class.

Hah! Well, there is that! Eff Fundies! I’d rather stick a fork in my eye!

It’s not can’t. It’s won’t!

 

[Marie13]

My homework is to plan dives for a weekend at Wazee Lake. Two sets of doubles, one with trimix and one with air. Try to get two dives (one deco, one not) out of each set of doubles. Also, a dive or two on the Hume.

I just ran some Hume dive plans at lunch. Usually only the one dive is done, although occasionally a 50-60ft wreck will be done on the way back to the marina. Ran it with both 50% and 80%, as requested.

 

[rddvet]

Out of curiosity why 25/17 (I assume was supposed to be a 25/15 mix) as opposed to a more standard gas like 25/25 or 21/35 (25/25 is a little too high p02 for me). I'd just run the 50% personally. Is your instructor having you compare 50% vs 80% as a test to show you it's not a huge difference, or is 80% popular up there?

 

[Marie13]

25/17 is what the MD best mix tool gives me. Standard gases aren’t banked by my shop other than 32% Nitrox. So doing a standard mix of 21/35 for shits and giggles is a waste of money when He is $3/cft and I don’t need an END that shallow.

Some use 80% here.

 

[grantctobin]

Out of curiosity why 25/17 (I assume was supposed to be a 25/15 mix) as opposed to a more standard gas like 25/25 or 21/35 (25/25 is a little too high p02 for me). I'd just run the 50% personally. Is your instructor having you compare 50% vs 80% as a test to show you it's not a huge difference, or is 80% popular up there?

Thankfully 100% remains more common, esp among the CCR crowd

 

[BlueTrin]

@Marie13 , I happened to do ANDP last weekend.

We couldn’t do the last dive on Sunday because the conditions were too bad so I have still one dive to complete DP but got AN.

I was quite narced at 135ft when I was executing the plan. I am tempted to do Heliotrox now.

edit: I was at 42m which is roughly 135ft, not 150

 

[Marie13]

@Marie13 , I happened to do ANDP last weekend.

We couldn’t do the last dive on Sunday because the conditions were too bad so I have still one dive to complete DP but got AN.

I was quite narced at 150ft when I was executing the plan. I am tempted to do Heliotrox now.

I have had people poo-poo Helitrox, telling me you don’t need helium until 160-170’. I laughed. I know my narc level at 130’ was bad. I can’t imagine what it would be at 150’.

 

[rddvet]

25/17 is what the MD best mix tool gives me. Standard gases aren’t banked by my shop other than 32% Nitrox. So doing a standard mix of 21/35 for shits and giggles is a waste of money when He is $3/cft and I don’t need an END that shallow.

Some use 80% here.

The reason I ask is making a mix of something like 25/15 is a bit of a pain for the filler compared to the standard gases and with standard gases since most are based off of a nitrox topoff (except 30/30), you will have an easy to figure out mix after the dive when you top off with 32%. Some instructors teach best mix, some teach best standard mix. I was taught best mix, but have been happier moving to standards. I think alot of factors go into if instructors teach best mix vs standard such as cost of local gas, whether they're ever the tank monkey that has to fill the odd %s, or just perosnal preference. It's interesting to hear the differences of how everyone is taught. I'm lucky enough that I fill my own tanks and locally He isn't nearly as high as those prices, so my view is skewed.

I have had people poo-poo Helitrox, telling me you don’t need helium until 160-170’. I laughed. I know my narc level at 130’ was bad. I can’t imagine what it would be at 150’.

People that poopoo Helitrox and Trimix and dive air to 160ft just don't realize that they're impaired in my opinion. I almost always have helium in my gas since a high percentage of my dives are in the 100-110 range and I know I can get unseen narcosis. I've enjoyed the helitrox cert more than expected. I don't do a ton of diving that necessarily requires "traditional" Trimix since the max depth is really 150-160, but with the updated tdi standards you're able to use "trraditional" trimix %s like 21/35.

 

[Marie13]

The reason I ask is making a mix of something like 25/15 is a bit of a pain for the filler compared to the standard gases and with standard gases since most are based off of a nitrox topoff (except 30/30), you will have an easy to figure out mix after the dive when you top off with 32%. Some instructors teach best mix, some teach best standard mix. I was taught best mix, but have been happier moving to standards. I think alot of factors go into if instructors teach best mix vs standard such as cost of local gas, whether they're ever the tank monkey that has to fill the odd %s, or just perosnal preference. It's interesting to hear the differences of how everyone is taught. I'm lucky enough that I fill my own tanks and locally He isn't nearly as high as those prices, so my view is skewed.

People that poopoo Helitrox and Trimix and dive air to 160ft just don't realize that they're impaired in my opinion. I almost always have helium in my gas since a high percentage of my dives are in the 100-110 range and I know I can get unseen narcosis. I've enjoyed the helitrox cert more than expected. I don't do a ton of diving that necessarily requires "traditional" Trimix since the max depth is really 150-160, but with the updated tdi standards you're able to use "trraditional" trimix %s like 21/35.

Instructor works in the shop and does just about all the custom mixes. So he will be filling my tanks.

 

[Jack Hammer]

One big real world advantage of 50% is it gets you to a breathable gas quicker if you have an issue. It also let's you use less trimix, which adds up quickly.

I still hear people saying HE isn't needed til much deeper than 150'/45m. I'll just say the 1st time I dove the Hume with trimix it was a much more rememberable experience than the all times I dove it on straight nitrox. It's worth the additional cost to better enjoy and recall the dive.