My First Post-Certification Dive Experience (Cruise Ship Excursion) (Long)

[1080iAddict]

I figured I would “pay it forward” and post my first post-certification dive experience to other newly certified divers that may be apprehensive to literally take the plunge.

As background for my post, I received my OW certification on October 31, 2004 and scheduled 2 dives on shore excursions during our cruise vacation on the Disney Magic over new years. The dives were located in Cayman Islands and Cozumel. Both dive profiles were described in the literature as 80 feet for 1st tank and 35-40 feet for 2nd tank. On another thread, I posted my thoughts on canceling the dives due to nervousness and apprehension due to my lack of experience. 98% of the return posts told me to go forward. So I did. And it was the most awesome experience that can hardly be described in words. I made some mistakes discussed below but it was a learning experience. Here is my review:

Cayman Islands

The Cayman dives were led by PADI instructors. I was quite surprised that the dive plan briefing on the boat was very much patterned after the certification lesson plans. We were presented with the table diagram and shown the RDP, and we were told the profile called for 80 feet for 30 minutes bottom time followed by a 40 minute surface interval and then a 35 foot shallow dive for 40 minutes (all this based on my recollection – my dive log is at home so depths and times may be off a bit). We were told to ‘plan the dive and dive the plan’ (where have I heard this before?). The instructor / DM went over hand signals and told us 500 psi was the air limit, and when we hit 1,000 we should signal him, and not to wait for 500 psi for the initial signal. When the first buddy group hits 500, we all would surface for a 15 foot safety stop for 3 minutes. We were told that after the giant stride to meet at the bottom.

The dive differs from the certification dives inasmuch as there is no farting around at the surface upon water entry. You take the stride and immediately descend, following the anchor line down to the initial 40 foot floor. Once everyone is down, we dove to 75 feet down the wall. It was incredible. At one point, I saw a school of blue colored fishies and started to follow them. That little excursion brought me below the floor and my computer told me I was at 84 feet. The instructor was above me. This was my first learning experience – my body felt the same at 40, 60, and 84 feet. If you are not careful, it is easy to go deeper and not know it. Anyway, at the end of the dive, we ascended to the safety stop and I found myself trying to maintain the 15 feet without surfacing involuntarily, so I grabbed the anchor line and even wrapped my feet around the bottom to stop my ascent. More on that later. We then surfaced and got back on the boat and I had a similar experience for the 2nd dive.

The experience was amazing. The viz was at least 40 feet I think – absolutely clear water – and there was so much to look at including lobsters, fish, and even a sea turtle which I touched. That was my second learning experience as I was scolded back at the surface for touching the wild life which apparently you are not supposed to do. I wore a full body wet suit – I was warm. Others were cold. The boat is crowded so you do need to be efficient.

Cozumel

The Cozumel dives were led by Mexican dive masters. The dive plan briefing was not as much patterned after the certification lesson plans and were in broken English. We met on the bow of the boat in a group of 6 on the way to the site. We were told this was a drift dive at 75 feet for 35 minutes bottom time followed by a ‘surface interval’ and then a 35 foot shallow dive for 40 minutes (again based on my recollection). The DM went over different hand signals and told us 700 psi was the air limit and at 700 psi he would float the dive buoy. When the first buddy group hits 700, only that group would surface for a 15 foot safety stop for 3 minutes and then we all meet at the buoy. That made me nervous. How would we all get together again? Would the boat miss us? More on that later.

This dive differs from the certification dives inasmuch as there was no anchor line and it was a drift dive. The boat suddenly stopped and the DM shouted “vamos” and dove in. We freaked. He was 20 feet away from the boat by the time the first of us jumped in after him. But we all eventually met at the bottom. It was even more incredible than Cayman. You simply set buoyancy and drift – no swimming required. The DM took us to an incredible wall and the water was almost ultraviolet deep blue – it was so absolutely incredible. The DM led us along the wall and then through tunnels in the coral – some of them 25 yards long. We transversed many tunnels and crevices, etc. This was absolutely incredible. When the first buddy group hit 700 psi, the DM inflated a bright red long buoy and it was attached to a string. It floats to the top so the first group can stay with the buoy. Then, as the rest of us ascended, the DM would take up the slack. That is how we all stay together as a group as I soon learned. The boat then came to pick us up and then picked up the 2 other groups of 6.

However, I again found myself floating above the safety stop involuntarily but there was no anchor line. So I start swimming down as hard as I can and get all cramped up in my calf muscles. I looked like an idiot flailing around trying to maintain 15 feet and not float up to the surface. I only realized after that dive what was wrong. You need to let the air out of your BCD as you ascend because the pressure decreases as you ascend and therefore your BCD ‘inflates’ with air. Yes, I learned this when I was certified but I forgot. I now realize how important this principle is to remember. On the 4th and final dive I ascended flawlessly and stopped at 15 feet like an astronaut. I wrote this down in my log so it never happens again.

The Cozumel experience was even more amazing than Cayman. The viz was again at least 40 feet and there was so much to look at including a barracuda which I apparently did not see (but I was told it saw me). The DM also signaled a ‘fin’ and pointed for a shark but I never saw it.

At the end of all my dives I got the log book stamped.

Conclusion

I am so glad I did these dives. Everyone on the boat is anxious to help and there was NEVER a feeling of “o – he is a newbie and will be a pain in the arse”. If you are newly certified, DON’T WORRY – just do it. I am hooked for life. If anyone has questions, please post and I will monitor the thread.

My only lingering questions pertain to the RDP. When I plotted my depth and bottom time off my dive computer, I exceed the RDP limits. But I was told that dive computers can extend your diving time due to actual depths and alogorithms etc. I never exceeded the NDL limit on the computer but I did get to the 'caution' part on the NDL display. I guess I am ok right so long as I follow the computer and generally know the limits on the RDP?


Regards,

Adam

 

[DBailey]

Touching animals - I was taught that touching animals causes them stress and could get them out of their normal routine. Plus, how do you like it when strangers come up and pet/poke you?

Dive Briefings - Expect many of them to be in broken english (unless english is the person's native language). If you don't pick up the important details in the first breifing, specifically ask the DM after the breifing (time, depth, turn point, emergency recall to boat, etc.). Not able to speak french, I have sat through a 15 minute briefing given in only french. My english only version of it was 1 minute long, since I only needed the important information and not the "fluff" story telling. The fluff can make the dive more interesting (if they point out facts history), but it is not needed for the dive.

Computer versus Tables - since the tables involve rounding upon rounding, they end up being very conservative. Computers use the same equations as the tables, but it tracks your depth and time; therefore, designing a custom profile for that dive. If you were able to eliminate all the rounding from the table, then you should be able to come close to your computer's calculations. I still use my table to get a "feel" for the dive as a back-up to my computer.

P.S. Glad you had a good time, and welcome to the addiction.

 

[Jim Baldwin]

Adam,

Glad you had a teriffic time in Cayman and Cozumel.

You obviously had good dive briefings and you found as most new divers do that you can easily get task overloaded simply by taking in the beautiful sites.

You forgetting to dump some air is nothing unusual. These skills will come second nature to you as dive and get more comfortable.

As far as the computer vs. tables. Remeber that dive tables are based on a flat dive profile as in 80 feet for 30 minutes.

In Cozumel you did a multilevel dive starting at 80 feet and the divemaster had you slowly ascending throughout the dive. So you got credit on your dive computer for the shallower part of your dive which is something that you can't do with the RDP.

You also found that these dive ops run like a business and that they want to come across as professionals because they have people like yourself that have paid a lot of money to come there. So no farting around.

Don't forget that at the end of the dive the aluminum tanks that you were using became about four pounds positive which will also tend to make you butt float even if your BCD is empty.

You also found out why many veteran divers will book their own diving when they go on a cruise simply because they want more room and fewer people.

Had you had a great trip my wife and I are headed to Cozumel Sunday for seven days.

Jim
Louisiana

 

[Divemastr]

Good points all. Adam, Welcome to the addicted. I read the other thread you mentioned. Glad you made the decision to continue. I REALLY like Cozumel. GREAT diving there. I remember one of my tours during my OW training (at end actually) where I had managed to get water in my BCD because I was not upright when I tried to let air out of the BCD. Next time I inverted to reach something and was ascending, I had a hard time getting upright again as my ascent became faster and faster as you mentioned above. It was interresting. I remembered that my ProQD BCD has a dump valve in the bottom. This allowed me to dump the air and stop te ascent. Moral of this story is to dive often and really learn your equipment. I typically do not rent equipment unless I have managed to forget something. I like the familiarity and comfort I have using my own equipment.

Jim, I am jealous.. I don't get to go again to Cozumel until Feb.

 

[Diver0001]

I figured I would “pay it forward” and post my first post-certification dive experience to other newly certified divers that may be apprehensive to literally take the plunge.
....snip....

My only lingering questions pertain to the RDP. When I plotted my depth and bottom time off my dive computer, I exceed the RDP limits. But I was told that dive computers can extend your diving time due to actual depths and alogorithms etc. I never exceeded the NDL limit on the computer but I did get to the 'caution' part on the NDL display. I guess I am ok right so long as I follow the computer and generally know the limits on the RDP?

Terrific dive report, Adam. Good learning experiences well described.

As for your lingering question:

The same general principles apply to diving with a computer as with the tables. Things like safety stops, avoiding saw-tooth profiles, rules for surface intervals, deepest first, slow ascents etc. all apply. In some sense they apply even more because a computer works out the dive based on sampling your depth every couple of seconds and the nitrogen loading it's displaying can actually be (quite) a bit closer to the "real" NDL than you would get on the tables for the same dive. It has to do with the computer eliminating almost all of the "rounding error" you get with the tables.

It's true that you should be able to go to the surface as long as you stay withing the NDL's on the computer (assuming you follow the safe diving practices you learned in OW) even if you're "off the tables". However, you cannot switch back to the tables from the computer (actually you can but it's quite beyond the scope of this post) and you should always use the *same* computer for any sequence of dives in the same 24 hour period becuase your computer remembers your nitrogen loading and keeps track of your surface intervals too. Good advice when using a computer is to *always* make a safety stop and to make the safety stop long enough that the computer backs out of the caution zone if it's possible/practical to do so.

R..

 

[1080iAddict]

Good advice when using a computer is to *always* make a safety stop and to make the safety stop long enough that the computer backs out of the caution zone if it's possible/practical to do so.

R..

Interesting. I was glued to the 3 minute counter and didn't even think to watch the graph backout of the caution zone. I will next time. I feel better after reading these replies because I sort of freaked afterwards when I filled in the log book and when it asked for the pressure group I was off the chart. As a textbook question - what do you do when you are 'off the chart' and you want to fill in the pressure group in the log book? Just go to the next lowest letter?

 

[MikeFerrara]

The DM led us along the wall and then through tunnels in the coral – some of them 25 yards long. We transversed many tunnels and crevices, etc. This was absolutely incredible. When the first buddy group hit 700 psi, the DM inflated a bright red long buoy and it was attached to a string. It floats to the top so the first group can stay with the buoy. Then, as the rest of us ascended, the DM would take up the slack. That is how we all stay together as a group as I soon learned. The boat then came to pick us up and then picked up the 2 other groups of 6.

However, I again found myself floating above the safety stop involuntarily but there was no anchor line. So I start swimming down as hard as I can and get all cramped up in my calf muscles. I looked like an idiot flailing around trying to maintain 15 feet and not float up to the surface. I only realized after that dive what was wrong. You need to let the air out of your BCD as you ascend because the pressure decreases as you ascend and therefore your BCD ‘inflates’ with air. Yes, I learned this when I was certified but I forgot. I now realize how important this principle is to remember. On the 4th and final dive I ascended flawlessly and stopped at 15 feet like an astronaut. I wrote this down in my log so it never happens again.

The Cozumel experience was even more amazing than Cayman. The viz was again at least 40 feet and there was so much to look at including a barracuda which I apparently did not see (but I was told it saw me). The DM also signaled a ‘fin’ and pointed for a shark but I never saw it.

I hate to be the party-pooper here but this is probably why some recommended you get some experience before doing those dives...

Overhead environments with no training and planning for such.
Doing fairly deep dives before you can even hold depth at a safety stop.
Not understanding your the decompression planning for the dive you're doing.

I think you're lucky but I'm glad you had fun.

 

[Damselfish]

Interesting. I was glued to the 3 minute counter and didn't even think to watch the graph backout of the caution zone. I will next time. I feel better after reading these replies because I sort of freaked afterwards when I filled in the log book and when it asked for the pressure group I was off the chart. As a textbook question - what do you do when you are 'off the chart' and you want to fill in the pressure group in the log book? Just go to the next lowest letter?

In this case you were really following the computer, so I don't think there's much point in filling out the pressure group from the table in your log just for the sake of doing it - especially if you don't have a valid one to fill in. You'll probably discover after a while that you find certain things useful to log and others not worthwhile. These don't always match up to what your logbook happens to have slots for.

 

[DBailey]

If you are diving a computer, then note it in your log book somewhere for the dive. I note the manufacturer and model number, and the way the computer is currently set (nitrox, altitude, cold water, etc.). That way, if something does happen, someone can look back into my log and have most of the information to recreate the past.

I fill out the dive profiles, but the moment I am "off the chart" I just make a "computer used" notation instead of a pressure group. I also pay attention to where my times fall. If I am way off the table, I start recalculating to confirm. If you are relatively close to the table, then you can chalk it up to the table's conservatism through rounding.

 

[Diver0001]

Interesting. I was glued to the 3 minute counter and didn't even think to watch the graph backout of the caution zone. I will next time. I feel better after reading these replies because I sort of freaked afterwards when I filled in the log book and when it asked for the pressure group I was off the chart. As a textbook question - what do you do when you are 'off the chart' and you want to fill in the pressure group in the log book? Just go to the next lowest letter?

Don't bother. As I said you can't fall back to tables from the computer anyway so anything you fill in is just a guess.

If you want to make an accurate guess then you can go to the computer's planning mode directly upon surfacing and look at what it shows you for the adjusted NDL for say 60ft. Say it's 35 min. Then go to the back of the table and look up where you see 35 min on the adjusted NDL"s and read up to see the group.

NOTE:!!! this is not how you fall back to tables but it is one way you can coax your pressure group out of most computers. Having said that, it remains a guess becuase most computers these days apply much more sophisticated deco calculations and even different deco models than the table is based on. It's like having two maps of the same thing but with different scales. You might be able to line them up at one point but somwehre it's not going to fit.

So....in short.... just don't bother with pressure groups when you're using a computer.

R..