Dive planning (or not)

[NudeDiver]

Plan your dive, dive your plan. Nice mantra. Got it.

Now - the reality is that we (me and whomever I happen to be diving with) don't do a whole lot in the way of planning. The "plan" basically consists of "dive until one of us burns about 75 bar and then turn back, and be on boat/shore with 50 bar remaining". As far as depth goes - when getting close to the NDL - go more shallow. Not that we're going very deep anyway. More than 20m is a rarity. More than 25m is almost unheard of. The "dive objective" in most cases amounts to "go down there, fin around, see whatever there is to see until it's time to go back". This is true whether I'm with my "regular buddy" and we're shore diving locally, or if I'm with an instabuddy on a day boat or liveaboard.

Nowhere anywhere have I ever seen anyone have any kind of detailed plan about how deep for how long - or even much of a plan at all. It all seems to be about how long the air lasts - and keeping enough for a safety stop (or finning along at 5m for 3 minute while in transit) and being done with 50 bar.

So what's the deal? Is this some sort of evil horrible deed, or is this the reality of most "casual" divers or what? It seems like developing a plan and then following a plan that puts you back at the surface with half a tank is a waste of gas. I don't think I (or anyone else I know) will EVER be able to accurately develop a detailed plan based on predicted consumption rates that puts me (them) back with 50 bar.

So what gives? Am I, and everyone I've ever dived with, just a horrible diver?

 

[vicdiver656]

When I dive (usually with the same buddy, my dad) we just talk a bit about the dive, what to expect, who'll be the leader, what our turn-around pressure will be, and where we'll go. Occasionally, we'll go more in depth and say what the max depth will be, but we usually have a bottom of around 80 anyways, so we don't worry about that too much. The safety stop at 15 ft is always a reminder every dive, we both make sure each other knows to do it, and we run through an S-drill in the water.

 

[almitywife]

even after 10yrs my hubby and i still discuss our dive before we get in the water but it might happen during the week/on the way to the site. we are very familiar with our dive sites so we already know the depth and the general plan but we still discuss the entry point, where we will be heading to and what we are aiming to achieve during the dive.

when diving with people other than my hubby its quite similar but we go thru hand signals just in case and agree on a turn around point/air pressure

cheers

 

[chris9562]

Yeah, i bet you do plan more than you think.
You probably discuss the site you'll be diving
You probably discuss when you'll go in the water
You probably discuss What Hand signals you'll be using
You probably discuss what bar to start back at, min surface bar
You probably discuss what you hope to see
..
just me, but i always do the above, even in just conversation.

 

[katdiver]

Sounds ok to me. Over the years that's what I've done. Teaching is something else, yes there has to be the plan with all the limits. There again, that's just what you do, you set your limits and follow your "plan", no problem. I know a guy who works his dive profile backwards on a wheel, so if his computer ever gave up, he knows his pressure group and carries on diving. That's the beauty and ease of this type of diving, dive conservatively, keep away from the limits and have fun while your air lasts.

 

[tstormdiver]

Most of the dives I do at the quarry are much like that. We pretty much discuss what sites we will go to & possibly a couple of emergency procedures (lost buddy....) that may be a reality there. Unless I'm diving with a beginner or someone new who doesn't know the quarry, we pretty much do the same dive. I will admit though, there is a bunch of area in the deep end that I have not yet dove.

 

[Tortuga68]

The "plan" basically consists of "dive until one of us burns about 75 bar and then turn back, and be on boat/shore with 50 bar remaining". As far as depth goes - when getting close to the NDL - go more shallow. Not that we're going very deep anyway. More than 20m is a rarity. More than 25m is almost unheard of. The "dive objective" in most cases amounts to "go down there, fin around, see whatever there is to see until it's time to go back"

Well - that's a plan

IMHO the minimum plan for the type of diving you describe would include a pre-dive briefing (eg we're going here on the boat, backrolling, meet on surface, diving to this depth with these buddy pairs), making a safety stop on ascent (eg 3 minutes @ 3 metres), a lost budy plan (eg search for one minute then surface) and a low air plan (eg 50 bar = surface)

Did I forget anything guys?

The deeper you go, the more challenging your environment, etc etc, the more detailed your plan needs to be - but making your plan more detailed than it needs to be is just giving people more information to confuse themselves with

 

[NudeDiver]

All:

Thanks for the input.

While I realize there are many aspects of dive planning, my question was really about the gas management aspect. But based on the responses here, it doesn't sound like the diving planning practices I've been involved in are particular deficient for their purpose.

Thanks
nd

 

[String]

The "dive objective" in most cases amounts to "go down there, fin around, see whatever there is to see until it's time to go back".

Sounds perfectly acceptable to me. If you have no NDLs to worry about all you need to consider is that you both have enough gas to get 2 people to the surface. That's assuming you aren't both carrying redundant air sources - if you are then not even that is an issue.

Yes dives with mandatory stops and so on do require a LOT more planning but people stupidly over complicate a gentle shallow bimble like that above and turn it into something far more complex that it needs to be.

90% of our club diving is "drop in and swim around until about 75 bar, send DSMB up then surface" with the only added factor being the maximum dive time we told the boat cover (typically 45 mins or 1hr).

If you want to do similar but be REALLY conservative then you could use thirds rather than "75 bar" (which is nearly identical on a single 232 bar tank).

Note:- This typically works for dives where you can just come up wherever you are - in the less enlightened places on earth that make you go back to the boat you need to plan it a bit more.

 

[Tortuga68]

Heh, sorry - threads here have a habit of getting a little off topic

So, to get back to your original point, which I think is summarised by this quote:

It seems like developing a plan and then following a plan that puts you back at the surface with half a tank is a waste of gas. I don't think I (or anyone else I know) will EVER be able to accurately develop a detailed plan based on predicted consumption rates that puts me (them) back with 50 bar

While plan the dive, dive the plan is indeed a good mantra, there is room for variables in any good dive plan

For the recreational diving you're doing you would probably best be served by diving until you hit a spefic air limit (maybe 50-70 bar, based on the worst air consumption of your group/the minimum required to get safely back to the surface) and then gradually surfacing. I don't see any problem with that at the depths you dive, so long as you are buddied up and with competent divers

Plan your dives by going straight to the deepest point you will dive to, then work your way up slowly - that way if you find yourself at, say, 10m with lots of gas left, you can extend the dive. That will also virtually ensure you stay within NDLs, with the type of diving you describe

Unless you're doing a deco dive, the limit should be based on remaining gas, not time (not excluding when the boat crew - if there is one - are expecting you to surface as noted by a previous poster)

Dive termination should be based on the first diver to reach the pre-determined lower limit of gas (eg 50 bar) - the plus being that the shallower you get, the slower you will consume gas, the longer the dive wil last, and the less you will feel 'cheated' by ending the dive with excess gas (beyond what is required for a safe dive)

You and your dive mates should also consider getting basic dive computers, that'll make your life a lot simpler from a NDL point of view (if that's an issue which at 20-25m, it may not be - you'll most likely run out of gas before you hit NDLs anyway). They'll help just from a confidence aspect though - one less thing to worry about (deco tables etc) as well as being useful if/when you decide to go deeper

HTH - if I didn't explain something clearly, just ask; either I or one of the other guys will be happy to clarify