Starting in tec.

[Tracy]

I do all my planning in metric, but I generally dive in imperial... I can do either, but for ascents, I prefer the granularity of feet. I like to spend 10 minutes ascending from my 10 foot stop, 1 foot at a time, if conditions allow that.

But doing math in imperial - yuck.

Similar.
I do one meter per minute from my last stop at 6M.
Five minute ascent after deco clears.

 

[Miyaru]

I'm also curious if there's a consensus on the imperial vs. Metric debate. I'm thinking with tec that I may have to go full metric and only do the conversions when communicating with others when necessary but otherwise doing all of the planning and math in metric and not mixing units (ask NASA about that).

Some concepts in technical diving are based on the metric system:

• PO2 or partial oxygen pressure is expressed in bar/ata, not psi. You've already seen the 1.4 and 1.6 values in the nitrox course.
• Gas density is expressed in grams/liter or g/ℓ, not in lbs/cuft or some other impaired imperial unit.

 

[evandroairton]

I tend to go the other way in regards to Metric. Starting technical diving is a great time to make the switch. Your diving life will be much easier if you transition. All of the calculations can happen quickly in your head.
It takes about 6 months of diving before you stop converting it in your head and just know where you are and what pressure you are seeing.
In this age of backup computers instead of backup slates, it is even easier. You can leave one computer in Imperial and one in metric until you get it down pat.
I recommend it to all my students, about half run with it, half don't. I can transition seamlessly bewteen them, so I don't care much either way.

Here we use metric, although pilots use imperial, and my hyperbaric medicine training was using feet sometimes, the point is, metric is far easyer to make maths, you may use imperial to yourself, but if you do the maths and know the units, it would be quite usefull when diving outside the USA, or if you dive with non american divers

 

[Jim Lapenta]

When I was teaching AN/DP I wanted students to have a minimum of 100 dives in and at least 25 in the gear they planned to use. Double each of those (and 3x in the gear) is not unreasonable for an instructor to expect.

Before the class these were also my prereqs.
Candidates for this course should have experience diving in the conditions where the course is to be conducted (e.g., Great Lakes, Eastern US Seaboard, Florida Coast, St. Lawrence River (high current)).
They should have a better than fundamental grasp of buoyancy and trim and be familiar with the gear they will wear for the course.

Show up with poor buoyancy and trim, and you will not be allowed to take the class. No refund will be given.

Before starting the class, you should be able to hold stops for up to three minutes with less than 1 foot in variation. Five minutes or more is highly desirable! Gear use should be instinctual.

It is also not unreasonable for the instructor to require a check dive or two in order to verify skills. I had more than one person express interest and have the number of dives, but they were honestly a mess when it came to skills and gear choice/setup. In that case it was necessary to do some remedial work before putting them in a deco class.

The deco class is not the place to learn buoyancy and trim in SM or back mount doubles. That should be in place before starting.

There are many people who think they have decent SM skills. They don't.
Every student was also expected to understand that I might be picking apart their gear, denying them the use of some item, reconfiguring hoses/routing, etc.

As to the SM/BM debate, it really didn't matter to me. I taught classes with people in both. Later on SM was the most often chosen because many of my tech students were going straight on to cave.
The ones that were heading towards wreck understood that they were likely to run into boats that did not support SM or that it would prove challenging.

SM in the Great Lakes can usually be done fairly easily on good days. Depending on the boat. In the ocean, it can get hairy because of the waves and some ladders. If you are going to SM on a boat, you better have your bottle handling down pat. You may or may not be able to use a drop line.

If they allow it, how long is it going to be to avoid banging the hull?

Are you strong enough to waddle around with bottles on your side instead of on your back? It's not as easy.

Is the ladder wide enough to allow you to climb with both if the crew won't take a handoff of a cylinder?

How will you secure your tanks on the boat?

Tech or recreational charter? Tech charters can have less people to work around but they are also carrying more stuff. Rec charters can end up full and diving SM on these is a pain in the ass.

I've done SM off boats and some are much more friendly than others.

And while it seems a good idea, and as much as I went exclusively SM the last couple years for tech, if doing wreck penetration where I was expecting a lot of doors, I'd rent or borrow a set of doubles.

If you have extensive experience in SM, go for it. But be open to exploring BM doubles in the future and while you don't have to buy a set, you can rent them so having a BPW with singles wing in the overall cost is not that much. And you can rent or borrow a doubles wing if needed.

I had gear for many scenarios or a way to get it. There is no one right tool for tech diving.
And if you are really going to consider yourself a tech diver, you should be prepared to have thousands tied up in gear so that you can adapt to changing conditions and situations.

The problem with too many "tech divers" today is they don't do this. They try to use one tool for every situation and in some cases, it's not only the optimal one, it's a downright stupid and even dangerous choice.

 

[Tracy]

When I was teaching AN/DP I wanted students to have a minimum of 100 dives in and at least 25 in the gear they planned to use. Double each of those (and 3x in the gear) is not unreasonable for an instructor to expect.

Before the class these were also my prereqs.
Candidates for this course should have experience diving in the conditions where the course is to be conducted (e.g., Great Lakes, Eastern US Seaboard, Florida Coast, St. Lawrence River (high current)).
They should have a better than fundamental grasp of buoyancy and trim and be familiar with the gear they will wear for the course.

Show up with poor buoyancy and trim, and you will not be allowed to take the class. No refund will be given.

Before starting the class, you should be able to hold stops for up to three minutes with less than 1 foot in variation. Five minutes or more is highly desirable! Gear use should be instinctual.

It is also not unreasonable for the instructor to require a check dive or two in order to verify skills. I had more than one person express interest and have the number of dives, but they were honestly a mess when it came to skills and gear choice/setup. In that case it was necessary to do some remedial work before putting them in a deco class.

The deco class is not the place to learn buoyancy and trim in SM or back mount doubles. That should be in place before starting.

If people don't want to take an Intro to tec/doubles primer/fundies, I have no issue with that. They can bypass those courses at their own discretion and move directly into ANDP with me.
That said, many ANDP courses turn into an intro to tec on the first day. If there are multiple students and the others are ready for the course they signed up for, then you won't be able to take the course you wanted.
Some people do have a lot of good experience and they have solid skills, they can move directly into higher level courses. Many just think that they have those skills.

 

[noserider]

As others have said, wreck diving typically involves diving off a boat and twins is much easier and more compatible with diving off a boat than sidemount.

Metric is a little easier, but you are better off learning imperial as the vast majority of divers you meet in the US and Caribbean will use it. There is probably less than 10% of divers who know metric in the US and even fewer can seamlessly transition and use it. Don't overly complicate things.

Plans are great, but in my experience scuba plans rarely last the test of time. I tell people to focus on getting more time under water, get deco certified, and then dive some more. Too many people treat it like a predetermined quest. A quest they complete in 3-4 years and then suddenly stop diving because they completed their quest.

Disagree about the Caribbean, a lot use metric bar a few islands overrun by americans.

To the OP just remember there is a whole big wide world outside of the US that has the worlds best diving where most use metric, so if you are diving planning to dive anywhere outside of the US do yourself a favour and go metric.

 

[VikingDives]

There are many people who think they have decent SM skills. They don't.

This.

 

[billgraham]

I think you're on the right track in terms of the physics but when you gonna learn how to swim? Maybe take one trip to Florida and do cavern and intro to get your brain and propulsion sorted out

 

[mr_v]

Learning metric and imperial won't hurt you.

I dive metric. It is easier in terms of gas planning, especially when calculating bailout needs. However, not everyone does this in the States and one of my computers displays depth in feet so that I can communicate deco stops with dive buddies without causing any confusion.