Planning Dives

[jgttrey]

In a quarry, how complex would you make your plan? Should I know exactly what features I want to see and how long I want to spend at each? Or just more basic plans since I can shears surface swim?

That part of the dive doesn't need to be rigid. If there are 5 potential things in one direction, you really just need to the point at which you need to turn around, whether you've seen all five or not. This is where communication with your buddy comes in. Figure out how to ask "are you ready to move on?"

How do I properly monitor our gasgas consumpt rates to better utilize that information for planning?

Record your starting and ending pressures on every dive, both you and your GF. Determine your average depth for that dive and the dive time, then do the math to calculate your RMV.

Just do some searches for the formula, but to take a very simple example. If you started with a full 80cf cylinder and breathed it down from 3000 to 750 in an hour with an average depth of 33 feet, then you consumed 60cf (2250/3000 * 80) of gas over an hour, or 1cf/minute. But, you did that at 2ATA of pressure, meaning at the surface, 1ATA, you would be using 0.5cf/min. When you determine that baseline, you can multiply it by the pressure at any target depth you are interested in, expressed in atmospheres of pressure, and figure out how many CF/min you'll be using while at that depth.

If you don't have a computer or comfort in calculating your average depth for a whole dive, then get to comfortable depth and maintain it for 15 minutes swimming normally, noting the starting and ending pressures just for that segment, and use just that segment for the calculation.

You'll find it varies significantly depending on how hard you are working and will likely be declining over time as you get more comfortable.

How do you plan where to go on an unguided dive when often times the boat captain doesn't even give you a dive site until you're en route? Do you just need to heavily research all the possible dive locations beforehand?

Only in the sense that we might be doing reef diving without knowing the particular site on the reef, but you would still be able plan gas, etc. based on knowing the typical profiles (i.e., first dive is a wall dive to 100', second is a 50' shallow dive) or something like that. If you ever found yourself in a circumstance where you felt like you were expected to dive on a site without any guidance and you weren't comfortable, then just don't dive until things have been explained.

You'll find that most of this stuff very quickly becomes muscle memory. You'll know, without having to think to hard about it, what your dive profile/length is for particular dives.

Just enjoy your dives and work up incrementally. If that means doing a 30 minute dive at 30 feet at first, that's fine. Master that and next time, add depth or time if you feel comfortable doing so.

 

[Alucard]

I agree - use something like Excel or Google Sheets to track your SAC for each dive. Note down whether any of the dives were obvious "outliers" (strong current, lost buddy, limited viz, etc.) so that you can start to see patterns. Work on getting a degree of consistency, both improving the average but also understanding what causes your consumption to be way above average. This also has the added benefit of improving your bottom time. When I started my SACs were all over the place. Once I became conscious of it, I started to work on improving it, so that now I am far more consistent.

Planning the dive really depends on what type of diving you want to do and what your objectives are. For most of my dives, I am air-limited rather than No-Deco limited, so the planning part of it is: We're going to drop down the line, check on the current, drop down the mini wall, head into the current until we hit half tank, turn around and come back along the top of the wall (using a lot less air because we are shallower and going with the current) until we reach the line where we started then tool around the bottom until we hit 800 psi, then go up to do the safety stop, and get back on the boat. If it's a shore dive, start heading back to shore underwater. I am on the boat or on the shore with well over the 500psi safety margin.

The danger with over-planning a dive like this is that you try to do too much, and don't just "go with the flow" and enjoy it.

Obviously some dives require more planning than this, but I would advise keeping it simple at first, and learning.

 

[Neilwood]

@jgttrey makes a great point at the end - if you aren't confident in your abilities at the moment, start with simple easy dives where you can both practise the skills you need going forward and slowly extend those boundaries.

If you have a dive computer, I would definitely look at a program like Subsurface - it will upload your logs and given start and finish pressures (with cylinder sizes) work out your gas consumption for you. It also has a generous area for comments so you can add notes like currents/ issues you had (which will affect your gas consumption). That way you can see the trend and also how various events affect it.

While doing the dives, get in to the habit of checking your gas against plan on a reasonably regular basis ie 5 minutes in to a planned 40 minute dive ask yourself "Am I at 1/8th usable gas or am I over or under? How is my buddies gas?". Once you dive a bit more you will get a feel for what it and your buddies (assuming a regular buddy) is likely to be.

 

[Scuba Doobie Do]

@jgttrey makes a great point at the end

He seems to be making a bunch of good points

1) Plus, a GREAT way to gauge your progress in relaxing - as you relax, you use/waste less air. If you enter your SAC or RMV in your logbook, it's fun to watch it go down over the course of a year's diving. It'll give you hard evidence of your improvement.

This is an awesome point. I should start tracking this regardless. It would be nice to have this data.

If you have a dive computer, I would definitely look at a program like Subsurface

I use a Suunto Zoop Novo and I have the download cable (you get awesome deals when someone at Walmart has some errors in the online posting). I'm have to see if the software allows this calculation basicall. Otherwise I'll have to check out Subsurface.

 

[Neilwood]

From what I understand the Suunto software isn't the greatest (never used it so can't be 100% on that). Subsurface is actually pretty intuitive and is multi platform (with cloud storage for logs).

It will accept downloads from pretty much any computer you can connect to and will work on PC,MAC,Linux, Android and Iphone. The beauty of this is that, should you change hardware whether it is your computer or DC, you simply use what you have, connect to the cloud and your profiles are all there.

 

[Scuba Doobie Do]

pay close attention to the dive briefing, and perhaps ask questions about key landmarks, current, and the recommended starting direction as you go exploring (generally INTO the current). As you listen to the briefing, think about the factors other posters have mentioned above.

This is something I really need to practice better. I listen to the briefings but usually don't pay as close of attention as I should. We are planning a trip to Destin Florida in June and plan to dive several times throughout the week. Maybe we'll get guides the first couple times and pay close attention, then try a dive sans guide.

 

[TMHeimer]

This is something I really need to practice better. I listen to the briefings but usually don't pay as close of attention as I should. We are planning a trip to Destin Florida in June and plan to dive several times throughout the week. Maybe we'll get guides the first couple times and pay close attention, then try a dive sans guide.

If you haven't been to Destin, the best shore dive is the "Thumb" jetty, but like all inlets in the area, wicked current unless you dive around slack tide. About 55 feet depth. You can also dive the "bridge" (US 98) by just going out & back, or walking a bit to the right and letting (not the STRONG) current take you back to the bridge. The parking lot is on the West side of the Marlor Br. on your left, but you need a permit from the Air Force now to park. It's free, but you have to take a silly online test. Dive flag required and advisable at both sites, particularly in summer I would imagine.
The folks at Emerald Coast Scuba can give you more details. Check NOAA for tide predictions (which aren't always perfect on the North Gulf Coast).
There are also several ways to dive the bays, none of which are very interesting dive spots.
Best dive on the Emerald Coast is St. Andrews Jetties St. Andrews State Park in Panama City Beach. For details contact Dive Locker in PBC.

 

[Kevrumbo]

Vis a vis the video above, it would be a huge disservice to the OP to have this thread go off on some tangent about UTD's Min Deco philosophy. I'll simply say that you can read all about it on other threads and that it is not without (a ton of) controversy. It should not be controversial to suggest out that unless/until you get some training on it, and make an informed decision as to whether it is a sensible thing, you would be wise to stick with what you learned in training about calculating NDLs and ascent strategy, which was likely to observe the NDL limits on your computer/tables and end the dive by ascending at 33'/min with a 3-5 minute safety stop at 15-20'.

You're in better more sensible control with a slower ascent rate of 10'/min starting at half max depth in a an emergency contingency air share utilizing UTD's Ascent Strategy & Rock Bottom Gas Management in the video above -rather than ascending straight from the bottom max depth at 33'/min, and then attempting to "jam on the brakes" at 15-20' for a 3-5 minute safety stop. . . (More likely for a novice dive buddy team in this instance to shoot all the way past safety stop depth to the surface)

 

[jgttrey]

I don't disagree with the advice to keep ascents slow and in control. Obviously, that is particularly true if you are not 100% confident in your ability to land on and then hold a safety stop. And, as I said, I think the rock bottom gas planning concept is preferably to an arbitrary number.

But, I don't think OP needs to, or should, adopt the Min Deco strategy in all its particulars simply to maintain a slow controlled ascent, particularly given that he has no training in it.

I'm not suggesting you were necessarily advising him to do that. We're probably not really disagreeing.

But, just to be sure, I wanted to express my view that he should not, on the basis of a few minutes of a UTD video teasing a class he could take, but hasn't taken, feel free to scrap his tables, computer and his prior training and adopt a dive planning philosophy that, whatever its merits, is different that most agencies' recreational recommendations.

Likewise, if he had initially trained with UTD, I would tell him to stick with that approach until, either through training or just more experience, he has the tools to decide what approach he thinks is best.

 

[Scuba Doobie Do]

If you haven't been to Destin, the best shore dive is the "Thumb" jetty, but like all inlets in the area, wicked current unless you dive around slack tide. About 55 feet depth. You can also dive the "bridge" (US 98) by just going out & back, or walking a bit to the right and letting (not the STRONG) current take you back to the bridge. The parking lot is on the West side of the Marlor Br. on your left, but you need a permit from the Air Force now to park. It's free, but you have to take a silly online test. Dive flag required and advisable at both sites, particularly in summer I would imagine.
The folks at Emerald Coast Scuba can give you more details. Check NOAA for tide predictions (which aren't always perfect on the North Gulf Coast).
There are also several ways to dive the bays, none of which are very interesting dive spots.
Best dive on the Emerald Coast is St. Andrews Jetties St. Andrews State Park in Panama City Beach. For details contact Dive Locker in PBC.

Thanks for the advice. IveI been pretty spspoil rotten with my dive history so I'm not really expecting too much from Destin. Really excited just to dive and meeting up with dive friends is always great. WillW be there all week so I'll have to check out PBC.

You're in better more sensible control with a slower ascent rate of 10'/min

I feel like even without adopting a new ascent strategy this is something great to practice.

@jgttrey, I definite agree that I shouldn't jump to something new yet. I'm also they kinda guy who will read 20 recipes for something and take little nuts and pieces... All info is good info so long as I learn from it.