Info A SATurner starts diving*... (*trials and tribulations of a 50+ year old out of shape guy learning to dive)

[scubadada]

Hello @scubadada, see post #43. As the Godfather's Pizza "Godfather" used to say, "It's in there.".

Sorry, I missed that with the RMVs reported so much earlier than the dive descriptions.

Some advice, take it or leave it. You do a lot of work generating SACs and RMVs that do not entirely agree. You are obviously interested. I would do one easy calculation and use that for your data. It would then be all comparable. I would consider using the SAC from your Perdix 2, it is available immediately from the on-board log and then from the Shearwater Cloud download.

If you multiply the SAC times the tank factor, you get your RMV. For an AL80, that actually has a gas volume of 77.4 cu ft:
SAC in psi/min x Tank factor 77.4 cu ft/3000 psi (0.0258 cu ft/psi) = RMV in cu ft/min

It is easy to track your gas consumption in a spreadsheet (I use Excel). The RMV calculation can be automated if you want. Generation of the mean and std dev can also easily be automated using the available formulas. Here is an example that took me just a couple of minutes to construct:

Your vote in the poll was correct, thanks for participating. I would be willing to bet that your RMV will decrease.

Take care, good diving

 

[SATurner]

@scubadada, part of why I showed the data in the manner that I did was to show that taking data out of a dive computer and putting it directly into "calculators" that might have a limited number of spaces after a decimal point or no decimal point at all are going to give similar (but not exact) answers to the dive computer's data. In shorter terms, garbage in, garbage out.

I do see what you mean about not needing to go through the exercise going forward though. I will get a spreadsheet going and keep historic data since I have all but one dive's data.

I have seen some mention here that some divers don't know what their dive computers are telling them. I think that is a very fair statement With all of the various models and modes, a comprehensive list might be impossible. I am hoping to learn more about what my computer is telling me, but without the ability to simulate a dive and "play" with the computer, I get limited to short interactions with it. Sure I can poke around while on the surface and change settings, but I don't get to see the immediate data differences that making those changes cause.

I am trying to poke around on the board a bit to find a thread that might be like a "dive computer 101" type thing. If I can't find it, I will consider trying to pull my questions together along with answers I have found and put it out for all to benefit from. Learning to dive is a lot like learning to do just about anything. When beginning, you don't know what you don't know to ask the questions to help you learn more at times. A great example would be learning the name of the boat you are on before splashing. Seems like a good idea, but how did you learn it? I learned it while being asked as I bobbed on the surface in Cozumel what boat I was on. I didn't have an answer. Ah Ha moment! Get the name of the boat next time. Lesson learned.

I will say that I just went through some material available through DAN eLearning that did a better job of explaining some of the effects of pressure on the body as well as the amount of energy used to do tasks at depth. Simple body movements use more energy which in turn means more gas consumption.

So, it becomes a bit of a challenge to be able to continue learning and practicing while not having ready access to buddies and bodies of water (I am sure I will sort something out). I had the thought today that if I cold find a reliable and cheap set of regs along with a weight belt, I could likely practice in the backyard pool doing things like mask removal, regulator drops, free flow drills, etc. Things that should become second nature so that if/when they occurred, there wasn't additional hesitation or panic on what to do. I think this would begin to reduce the multi-switching that one must do while diving and allow for some "auto pilot."

That's really the challenge in the beginning right? I mean there are multiple things going on simultaneously, but the human brain only does one thing at a time before going into multi-switching mode (multi-tasking is a myth!). Once multi-switching, tasks get prioritized and those with lessor priority might not get practiced or given as much attention as needed initially. For example, I could see benefit to simply doing a dive and focusing on nothing but the dive computer just to see the data it gives while finning, hovering, ascending, descending, etc. A dive or dives focusing on nothing but buoyancy, playing with weight placement etc. A dive for finning, in other words turning early dives into more singularly focused dives.

Just random thoughts of a new diver...

 

[scubadada]

Hi @SATurner

Keep things reasonably simple, the reason for my feedback. Keep track of the basic variables then use that information for improvement. I have a feeling that you are a good student and will improve significantly. I look forward to more installments from you

 

[SATurner]

I was able to go on anther trip with the local dive shop. The trip planned was Friday afternoon at Devil's Den, up early Saturday morning to swim with the manatees in Crystal River, then a drift dive down the Rainbow River in the afternoon, followed up Sunday by diving in Blue Grotto then heading home.

Dives #11 and #12: (Devil's Den)
If you haven't been to Devil's Den, it is a spring a bit southwest of Gainesville, FL. The entrance involves a very narrow set of steps with a low entrance (you'll likely have to duck) before going down a second set of steps to the platform for water entry. Think of an upside down mushroom and you'll have a basic idea of the spring shape.

When we were there, the water was up a bit less than a foot over the bottom platform so the "giant stride" method of entry was a bit less than normal. Still, it was good to splash and make sure that everything was in order prior to descending for the dives.

For those that haven't been I will point out that there are multiple swim throughs (some are tight). I don't know where you fall on the topic if swim throughs, but there is an entire discussion "Swim-through" okay for open water divers? if you would like to delve deeper into the topic. Disclaimer: Diving can be hazardous and decisions made while doing so could have dire consequences. Dive to your abilities which might be less than you realize.

While there are areas that are accessible with open water, in my opinion, the majority of this site should be considered cavern type diving. The visibility is such that it is easy to reference open water while deeper within the spring.

These were my first dives with my new gear. What new gear you ask? Well, I purchased a set of regs (still want to rebuild Dad's at some point) and a bc. My choice of gear ended up being Dive Rite. Some factors that went into this decsion:

1. USA Made
2. Local dive shop can/will service/support
3. From what I have seen of the brand so far, I like that it is purpose built (even if my purpose isn't likely to push the limits)
4. Seems to "future proof" well should my diving needs change
5. My dive buddy (really training buddy) was also going down this gear path

I also chose the reg set from them because it was put together as a package that included first stage, primary second stage, alternate second stage, spg, and lp inflator hose. Pricing out other options (of similar quality) typically ended up in a first stage and primary second stage for the same price then needing to purchase the alternate second stage, spg, and lp inflator hose. Seemed like there was always at least a $300.00 difference when complete packages were compared.

I chose the XT transpac harness with a voyager wing. The hydrolite was tempting, but I ultimately opted for more flexibility in wing choice. Maybe at some point a travel series wing will find its way into the gear closet?

These two dives were all about getting used to the new equipment, working on buoyancy, and exploring Devil's Den. All the gear performed well even though I didn't have all of the harness dialed in 100%. I didn't find things shifting too much and it all seemed to move with me.

Done diving for the day we headed to Crystal River for dinner and bed because the swim with the manatees had a 06:45 start.

If you haven't swam with the manatees, I would recommend it. It's a snorkel trip without fins. Practice keeping your legs straight and crossed while using your hands/arms to pull you through the water. Quiet is key, manatees spook easily. On our trip we saw enough to be interesting, but not so many that it was spectacular. I think that had a lot to do with being a bit late in the season. We did see some that migrated in from the sea (barnacles or barnacle scarring is a tell tale sign) along with some of the locals from the bay in Crystal River.

With weather approaching, the drift dive down the Rainbow River was cancelled. The winds were picking up and there was a decent storm on the radar. Alternate plans involved bowling. The bummer was that it was a "big bad wolf" storm that huffed and puffed and blew itself out. Of course by the time it was done, a few hours had passed as had the drift dive opportunity.

On to Blue Grotto....

 

[SATurner]

Dives #13, #14, #14.5, and #15: (Blue Grotto)
Blue Grotto is another location southwest of Gainesville, FL. This location has open water, cavern, and cave.

The first dive (#13) of the day was to go deep. Our group of six divers headed down and reached 78.9' before conditions silted and we turned the dive.

The second dive (#14) was simply exploration of the site with divers splitting off into pairs.

For dive 15, my buddy and I decided we wanted to try to go back deep hoping to make at least 80'. I skipped dive #14.5 because that was our first attempt to go deep. I had a flashlight malfunction (dead battery) so the dive was scrubbed. Our plan was to tie a reel off on the left side and descend. We would keep the wall on our left going down, turn and have it on our right coming out.

All was going well with me in front with the reel until about 45' depth when the reel backlashed. Stop, assess, solve. I wasn't sure if I would be able to remove the backlash or if I would end up needing to scrub the dive, wad up all the line and exit. Showed the backlash to my buddy and let him know that I would try to untangle it. It wasn't a terrible backlash and looking at the log, it looks like I spent just under a minute clearing it. In that moment, time slowed and stretched because it seemed to me like it took at least five minutes to sort that out. With the backlash cleared, I signaled "ok" and asked buddy if he wanted to continue down. I received "ok" back with a descend signal.

We continued down the left side of the site. When you're close to the side wall, there is a bit less room than descending down the center. At 80' depth, the dive alarm I had set on my dive computer let me know we had met our secondary dive goal (beating earlier dive depth). It was time to think about turning around. At this point, things were a bit too tight to easily turn around so again, in my mind I had to "figure out" the solve. Having spoken to others who had gone to max depth at this site, I knew there would be space to turn at a deeper depth, so I kept going until there was room for both of us to turn. This occurred at 91'9" and at that point, I stopped, signaled to turn and had my dive buddy lead while I rolled up the line on the reel. Whoever had used the reel prior had wound it "backwards" to me as I wanted to crank it clockwise to reel in and had to crank it counter clockwise to reel in. Not a huge issue until I would focus on something besides reeling in line and my brain would default back to clockwise reeling. So, the trip back up to untie was a bit frustrating due to this.

Once we untied the reel, we spent the remainder of the dive at shallower depths hanging out with the panfish in the spring.

Reflections on the weekend's dives to come (along with SAC and RMV data for @scubadada)

 

[SATurner]

Reflections on dives #11~#15:
The dives at Devil's Den did a good job of allowing me to adjust to new gear while also exploring a new environment. Focusing on buoyancy also allowed me to focus on breathing and minimizing hand usage. With practice it is entirely possible to change directions as well as depth without the use of hands. That might seem very obvious to an experienced diver. I offer it as a goal for those who are new and wanting to be better.

Devil's Den has many examples of swim throughs that might not take an "expected" path and could cause one slight panic if not prepared. If one is patient, it is possible to observe others entering/exiting to get a "feel" for what the path might be.

I am a bit torn with my experience at Blue Grotto. I say that because I was uncomfortable during my last dive, but also thankful for the experience. The last dive threw some curve balls at me (reel backlash and lack of turn when desired) that I had to resolve. Uncomfortable might not be the right word, tentative perhaps? I recognized that I was being task loaded by the challenges that popped up.

There could be some reading this that say I had no business at either site. I might be inclined to agree with them if it was ONLY myself and my dive buddy at the sites. At both locations, there were others watching to make sure that I wasn't getting into bad situations.

I would welcome feedback based on what I have described fully knowing that there could be some here that might chew me out like a teenager after their first fender bender. I recognize that the error tolerance isn't as high in scuba as it is in other things.

@scubadada, here are my SAC/RMV results: (looks like RMV is continuing downward)

Dive #​	SAC (PSI/min)​	RMV (ft³/min)​	Notes:​
11​	27.56​	0.71​	​
12​	27.98​	0.72​	​
13​	29.41​	0.76​	deep dive for AOW​
14​	23.28​	0.60​	​
15​	28.73​	0.74​	dealt with reel backlash​

​	SAC (PSI/min)​	RMV (ft³/min)​
Mean:​	28.62 ​	0.74 ​
Standard Deviation:​	4.85 ​	0.13 ​
Range:​	21.41 ~ 40.9​	0.552378 ~ 1.05522​

I did find the thread Why Surface with 500 PSI? which further expanded my knowledge. I now have one side of my slate dedicated to this data (wet notes at some point in the future). Thank you @rsingler for the information and spreadsheets!

Next trip is scheduled for mid April in Panama City Beach, then it might be a long surface interval until mid July in Cozumel. Not sure I can pull off an aquarium dive for my birthday in May.

 

[scubadada]

@SATurner

Change your RMV range to 2 sig figures, like the others, 0.55-1.06

 

[SATurner]

Change your RMV range to 2 sig figures, like the others, 0.55-1.06

That is some Excel (Librecalc) wizardry I haven't mastered yet. It worked until I did the range cells. Here's what I have in the cell for the range =C4&" ~ "&C5 where C4 and C5 are the cells with the low and high values which are only 2 decimal figures.