Looking to learn from my mistake...

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sonofzell

Registered
Messages
46
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29
Location
Philadelphia, PA
# of dives
25 - 49
Greetings!

I'm a relatively new diver - I've been certified for 4 years, but sadly my schedule and budget do not allow me to get out nearly as much as I'd like! I was able to squeeze in a beach dive this past weekend. It was the first time ocean diving from shore for both my daughter & I.

While the dive itself was relatively uneventful, I recognized some poor judgement on my part that raised some questions regarding navigation. Fortunately, the consequences ion this case were minor, but the need for improvement seems pretty obvious to me...

#1: Measuring and tracking distances underwater.
During this dive, we were advised of the locations of several reefs using visual points of reference both on and below the surface. We aligned with a particular buoy, surface swam until we were parallel with the end of a rock jetty, and submerged. At depth, we proceeded due east for approx. 50yds and found the first reef, exactly where we were told it would be. The remaining waypoints were simply approximated distances ("when you get to another sand bottom, swim another 25yds, you'll hit the next reef", etc.). In this case, the reference points were pretty idiot-proof, but my question is: Hypothetically... If we went off-course and "missed" our landmark(s), how would we confidently know HOW far we'd swam? Using only my estimations, the directions we'd been given were pretty spot-on, but I can easily see how simply "using my judgement" could lead to a dangerous situation, especially in a poor-visibility environment. We were diligent about using our compasses to ensure we would be able to accurately return on the same course, but as for specific distances, I feel like there's surely a better method than basically estimating how far we'd travelled between points A and B. I do carry a finger reel, but it is relatively limited in length (60', I believe). This particular dive being in Florida, I was also using this line to tow our SMB. I've done guided wreck dives in which our DM had used lengthy lines as guides, but truthfully never considered (perhaps naively) one of those large-capacity line reels to be "standard" gear. Using a similar line reel, I can see how distances could be easily measured; I guess what I'm asking is what, if any, alternate methods should I be prepared with to more accurately determine underwater distances?

#2: Current considerations for dive planning.
Here's where I really "dropped the ball" in terms of planning on this dive: given our shallow depth, we knew this was a no-deco outing, and mutually decided on both "turnaround" and "surface" thresholds based on air supply. Applying the "rule of thirds" and actively communicating, we executed the dive exactly as planned. Thus, you can imagine my frustration when we surfaced, only to discover that we were easily 100yds asea from our original point of descent! About 10 seconds after deciding to snorkel ashore, the reason for our miscalculation became painfully apparent: I had failed to account for the strong rip current when applying our return to shore! Even after moving longitudinally to dodge the rip zone, we ultimately spent over 30 minutes swimming against atypically strong currents before we were inside the break. As I mentioned previously, this was fortunately a relatively benign situation. We had left plenty of reserve air to inflate our BCs, deploy safety markers, or even re-submerge if necessary. Other than an unplanned workout, the only real consequence incurred was a bit of sunburn on my head and neck. That being said, the fact that I was SO FAR deviated from my intended reference point is very concerning. If any number of variables were different (daylight, equipment failure, rough chop, seacraft, etc.) this could have easily become a dire situation. My question here is: Other than improving navigation distances (#1), are there any common practices for "adjusting" dive planning in order to account for water currents?

Apologies if any of my questions are incredibly basic; these are just things that either weren't discussed extensively during my training or that I've just failed to adequately retain since I had not needed to apply them until now. I'm not the most experienced diver, but I'm smart enough to know when I've made a dumb mistake, and this dive seems to be a perfect example of just that.

Thanks in advance for any guidance in making this a learning experience!

-Kirk
 
The Navigation dive in Advanced Open Water will teach you how to count your kicks if precision is important. Not that you'll count every time you dive (it's pretty distracting) but you'll know roughly how fast you're going. And if you're doing something like going a certain number of yards to the next reef, you can count.
 
i usually try to use time instead of distance. obviously you would need to adjust the time depending on currents. that becomes a judgement call. but unless you are swimming long distances it is usually pretty easy to come close.

as mentioned above, you can also take a line down. measure a specific distance. then count kicks required, at your usual pace, to go that distance. it gives you a rough idea to use for future reference.
 
The other thing I would say is that 100 yards off from a multi-point navigation is actually pretty good. Sure, try to hit it bang on. But barring scary local conditions (rough chop, boat traffic, suck-you-out-to-sea currents) there's no big problem if you surface, take a heading to your exit, and swim back. Sounds like you did a good job with gas planning to allow that.
 
The Navigation dive in Advanced Open Water will teach you how to count your kicks if precision is important.

This is true, but you don't need the class to measure your kick cycle. In fact a few quarries I have been to had lines set up for measuring your kick cycle. If the place dive does not have a line with known distance, you could always run a line yourself.

You can either measure the time it takes to travel the line or how many kick cycles it takes you to travel the line.
 
Kick cycles, timed swims should be part of OW really. As well as SAC rate determination.

@sonofzell

You may be interested in my dive planning doc that I wrote for my own OW students that you can find here: Kosta's Dive Documents - Google Drive. Maybe something in that doc will be useful to you.
 
You can start from fixed underwater landmark, set a heading for another only a short distance away (10-15 kick cycles) and within clear sight. While maintaining your heading and looking only at your compass swim your estimated kick cycles needed and see how far off you end up. Return to the starting mark and adjust your heading to account for the drift. Any Underwater Navigation course will cover this. I'm not necessarily a course promoter or anything, but NAV was really fun and very informative.

*Edit- Also, if you notice over that short distance that the drift from your course is significant, that should be a trigger to at least consider whether it's worth continuing or not. Local reports on currents and such should be pretty readily available, especially if a location is prone to strong currents or tides.
 
Great suggestions on getting a feel for kicks - thanks to all! I've actually marked the line I currently use (it's doubled as a kayak anchor line / depth gauge on at least one occasion), so I should be able to "dial in" a reference once my local quarry re-opens next month. I suppose the remaining challenge, however, is how to get a feel for what adjustments would need to be made to consider the effect of kicking with/against any significant current. Perhaps this is something I just need to develop with continued practice (?). Unfortunately, there's not much opportunity for that in PA, but I'm lucky that I do typically visit the sunshine state at least once or twice a year to visit family. Either way, I can totally appreciate how at least gaining a baseline feel for my kick cycles will be a great reference to use as a foundation.

@wetb4igetinthewater - thank you for sharing that material; looks like there's some great info there!

P.S. - One massive check in the win column here is that my "local quarry" is Dutch Springs, which has a ton of submerged waypoints and is an incredible resource for practicing nav skills! It's something my daughter & I enjoy working on, but I guess our mistake has been focusing solely on headings and hitting waypoints without using the guide lines. Distance and kick cycles had never been a consideration.




pic_11695_35918.jpg
 
That's Awesome! Here in Colorado we've got two main choices that vis ranges from the glass of your mask (ZERO) to about 20' and Nothing exciting to see but crayfish and an intentionally sunk plane, or a toilet..in S#$%ty vis. Great spots that we did Nav, S&R, Rescue in though. learning in crap conditions.... Rad you and your daughter are dive buddies too!
 
Kick cycles, timed swims should be part of OW really. As well as SAC rate determination.

Not with PADI. OW only included a short introduction to using a compass.

but I guess our mistake has been focusing solely on headings and hitting waypoints without using the guide lines. Distance and kick cycles had never been a consideration.

After my wife and I completed our PADI open water last year, we felt less than adequate in really any skills including buoyancy. Our navigation was horrible. We went to one of our favorite spots that had a compass course to work on it. We first just focused on keeping our heading. with 20-30 feet visibility, we were able to find what we were looking for. After we got the hang of keeping our heading we started working on counting/timing our kick cycles. This really helps when you have a bit of a swim to your destination since you have a general idea of how far you traveled. Before that, it was just a guessing game and there were times we would either completely overshoot our destination or we turned around thinking we missed it. One thing to keep in mind is you may need to reevaluate your kick cycle as you progress. My kicks were really inefficient originally. Further, I mainly flutter kicked when I started but now I mainly use a frog kick.

OW really doesn't teach you kick styles either. I think those were part of the AOW and PFB.
 
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