Plan your dive and dive your plan

[TSandM]

I think of a lot of dive planning as setting parameters. I want to know, before I get in the water, that we will not be going any deeper than "x". I want to know that we have a planned dive time of approximately "y". I want to compare my gas supply with those numbers and feel comfortable that I have enough, and I want a plan for where we are going to turn around, gas-wise, to get back to the boat or to shore. (Gas plans aren't as simple as "rule of thirds" -- they vary with the kind of dive you are doing.) If there are navigational parameters, the whole team needs to know them, so that everybody can be paying attention to whether we are on course.

And finally, agreeing on protocol for any issues is important. What do we do if we get separated? What do we do if someone runs low on gas? Settling those things ahead of time makes everything run more smoothly (says Lynne, reflecting on a dive we did last year with a good friend, where we DIDN'T discuss separation protocol, and ended up having a very anxious and uncomfortable experience).

I started a THREAD on this topic a while back, and people wrote a lot of good stuff on it.

 

[fjpatrum]

Clearly I'm missing something. You know the dive profile, IE max depth, and the expected time you'll be there based upon your consumption rate. You give yourself a turn pressure &/or a turn time. Other than what to do in an emergency, how is this not a dive plan? You have all the relevant information you need to perform a safe and enjoyable dive.

Sounds like a plan to me.

That said, one of the operators we just did dives with last week basically said "bottom time for first dive is 25 minutes for air and 45 minutes for Nitrox" because that was a reasonable nitrogen load to get a 1 hour surface interval before the second dive and not have any issues. It worked out fairly well for most people because we all seemed to be getting about those times for consumption anyway... bunch of gas hogs I guess.

 

[rx7diver]

No one uses dive tables anymore ...

Not quite accurate. I use tables almost exclusively. (I don't use the one-third rule when rec diving, though.)

Safe Diving,

rx7diver

 

[emoreira]

I started a THREAD on this topic a while back, and people wrote a lot of good stuff on it.

TS&M, I made one of the most common mistakes here in SB, do not search wisely BEFORE starting a new thread.

---------- Post added May 9th, 2012 at 03:41 PM ----------

Clearly I'm missing something. You know the dive profile, IE max depth, and the expected time you'll be there based upon your consumption rate. You give yourself a turn pressure &/or a turn time. Other than what to do in an emergency, how is this not a dive plan? You have all the relevant information you need to perform a safe and enjoyable dive.

Sounds like a plan to me.

That said, one of the operators we just did dives with last week basically said "bottom time for first dive is 25 minutes for air and 45 minutes for Nitrox" because that was a reasonable nitrogen load to get a 1 hour surface interval before the second dive and not have any issues. It worked out fairly well for most people because we all seemed to be getting about those times for consumption anyway... bunch of gas hogs I guess.

After reading all the answers, I finally arrived to the same conclusion. I do plan my dives. I thought that what I was doing was not enough.

 

[TSandM]

emoreira, don't feel bad at all! You brought up a good topic, and brought it to current attention. The thread I linked to was old, and nobody had added anything to it in years. It was unlikely to get anyone's attention again.

 

[freewillie]

For me dive planning does not take into account calculated bottom time. Too many variables between water temp, exertion, currents, time at depth. It is nice to ballpark the time, but IMO should not be hard/fast rule.

I plan the site by making sure when I call the dive boat that the site is appropriate for the least experienced diver in the group. I make it clear to the operator there are beginner divers and is the planned dive site appropriate for beginners.

We pay attention to the predive briefing. If it is a DM led dive we make sure to have an idea of where the dive should start, what course we should follow, and what the max depth and turn around PSI signals are discussed before we get in the water.

Specific buddy pairs are identified even when diving in groups. Generally I will tell my dive buddy/daughter I want her next to me at all times. We also confirm separated buddy protocols. I also like to discuss how we will explore since it drives me nuts when I want to take it slow and look over the reef for small creatures and the diver I'm instabuddied with takes off like the Indy 500.

For me turn around time is more a function of what PSI level do we decide to head back and making sure we have enough gas for deco stop. The actual time is not generally set since how slow or fast a diver goes through their air is too dependent other factors.

 

[wedivebc]

I am surprised nobody has mentioned yet but it is easier to plan multi level dives using tables than it is with a dive computer.

 

[agilis]

I use the tables with an approximately 10% to 20% time reduction as my primary guide, computer for back up, for very irregular depth profiles and unforseen circumstances. Not being able to understand and use the tables is like not being able to drive a standard shift vehicle. You may prefer the easy convenience of an automatic, but you really don't know how to drive. Not really. I have to laugh at people trying to rent a car in some obscure destination who are unable to drive what's available.

 

[RonFrank]

On the Peace waiting on breakfast with my favorite buddy Tom. Our dive was going to be max depth 80', swim about for 45 minutes and gradually surface. The DM found us and informed us the the dive is BEFORE breakfast and we had less than 40 minutes until the boat was heading to the next island. IOW's get in the water now or not at all.

We had less than ideal time to do a relaxed pace so we quickly modified the plan. The new plan was to hit bottom around 120' and then follow a ridge up staying ahead of the NDL for 30 minutes. When the ridge ended around 40' then follow the kelp and SS at 15'. We turned a moderate dive into a deep dive in a matter of minutes. Its handy that we both have an understanding on how long, how deep and our overall objective without much talking. We were in the water in 5 minutes planning as we geared up.

Something else we always do is to check out one an others gear. Dry suit hose, inflation hose, octo, dry suit zipped, etc., check. Splash, OK at the surface and thumbs down. We descend together and stay together. With 40' vis its not hard but that's not always the case.

Good Diving to all.

 

[MXGratefulDiver]

Not being able to understand and use the tables is like not being able to drive a standard shift vehicle. You may prefer the easy convenience of an automatic, but you really don't know how to drive. Not really.

... that's like saying if you don't know how to use a slide rule, you don't really know how to do math ...

... Bob (Grateful Diver)