Is this a Bad Dive Plan for Cozumel?

[gasgirl]

Hi Gasgirl,
My name is Matthew Atkins, I am the head of the training department at Blue Angel. Eva has asked me to respond to your concerns, as she is away at the moment involved in some business meetings, and is unable to respond personally. First, let me thank you for having this conversation. We are very dedicated to diver safety and education, and it's through conversations like this that many people learn and grow as divers. That is quite possibly the best thing that Scuba Board has to offer.

To address your concern about surface intervals. I have met with our reservations person who sent you the information. I have also reviewed the email conversation that the two of you had, and I think we have had a slight misunderstanding due to a bit of a poorly worded response. We would never ask a diver to enter the water for their repetitive dive before they are comfortable doing so. That having been said, from an instructor point of view, 60 minutes is not a number that we insist on. Our dives are chosen by the divers and divemasters together. We are not one of the shops who will tell you where you are going, but instead we are open to going where the group chooses, assuming that the weather permits, and the divemaster is comfortable that the divers on board are all qualified to safely execute the dive requested. Because of this philosophy, we sometimes do a combination of first and second dives that require more than a 60 minute surface interval. Conversely, we also do combinations that require much less than a 60 minute surface interval. Our surface intervals are then dictated by the dive profiles of the divers on board vs. the dive sites chosen. For example. when we dive Punta Sur, or Columbia Deep, we routinely do Columbia Shallows as the second dive. Because of the shallowness of this dive (average 25 ft) a surface interval is very rarely required at all according to to the algorithms that the tables and dive computers are based on. We then often choose to do a quick surface interval, then get into the water so that our clients can enjoy the extended bottom time that the shallow dive affords them, while avoiding an unnecessary extra hour sitting on the boat. It is our experience that most of our divers appreciate this approach to surface interval management, but again we will not ever ask someone to re-enter the water before they are well rested and comfortable doing so. I apologize if the impression was given that we may enter the water before a diver is comfortable in order to accommodate the other folks in the group. Nothing is farther from the truth.

I see that you are considering diving Nitrox while you are here with us. I routinely dive air on each dive, and have no problems avoiding decompression obligations, and I dive with a Suunto also I am a fan of people diving Nitrox to add an additional buffer of conservatism, especially on the second dive. I think with this approach, you have no need to be concerned about short surface intervals or going into decompression situations, it sounds like you are a safety minded diver who is making all the right decisions. I would ask that while you are here, if the group you are with starts preparing for a dive you are not comfortable with due to surface interval, depth, or for any reason what so ever, please let us know. Your safety is our first priority, and we always have a way to address problems if we know what they are.

Of course, if you wish to cancel your reservation you are welcome to do so, and I have outlined our cancellation policy for you in my email to you. I am hopeful though that you will join us as planned, and I am confident that you will have a wonderful time. I look forward to personally greeting you here, and hearing your full feedback on your experience while you are with us. Please do not hesitate to contact me with any questions or concerns you may have. And again, thank you for having this discussion, these things are important.

Sincerely,
Matthew Atkins

Thank-you, Matt, for taking the time to provide a response to this thread and clarify any misunderstanding. I realize that this thread may have put Blue Angel's reputation in jeopardy and I am truly glad that you were able to reassure the Scubaboard community in your own words. As I stated in my email to you, I am comfortable with the approach you have described and I am fully satisfied that we have chosen the right dive op for us.

Thanks again to all those who shared their personal experiences with diving in Cozumel with their Suunto's as I stopped thanking each one individually but please know it was very helpful to me and it was greatly appreciated.

And a special thanks to all those with deco training who patiently provided their advice - I got sidetracked with other issues but I did see your feedback and I have done more reading on safe ascent practices. I understand the concepts of off-gas ceiling and running stops much more clearly now. I do not intend on using my DAN insurance ever.

 

[DandyDon]

Glad Matt posted here for us. I've dived with him years ago. None better.

Spoiler

I probably don't want to hear what he says about my diving. :blush:

 

[old gaffer]

Attention: I am seeking opinions from divers who have first hand experience with Suunto computers only please! (For those who do not dive with Suuntos and do not know about the problems with the over-conservative algorithms that penalize repetitive dives with short surface intervals, please refrain from responding with non-productive critical comments!)

Brief background:
Shortly after purchasing my Suunto Cobra, I recall being advised by an instructor in Grand Cayman that it would be fine to incur a deco obligation at depth up to 10 minutes as it would clear during my multi-level profile as I ascended and did my safety stop. I opted not to voluntarily put my new computer into deco on that trip but I was diving in conditions and sites that easily allowed me to modify my depth to be shallower that the rest of the group.

Shortly after that, I switched to diving Nitrox, and I no longer came even close to my NDL times on my repetiitve dives, and so I never had issues with Suunto being too conservative even when we were doing five dives a day (albeit with longer surface intervals than 60 minutes) on any of our subsequent dive trips.

Fast forward to the present:
We will be heading to Cozumel in a couple of weeks and based on what I reviewed from other trip reports, I am concerned that the dive profiles for our two tank boat dives we wil be doing may be problematic for us as we are diving with Suunto computers.

Because of conditions specific to Cozumel (ie. swim throughs at depth and possible strong currents), I am anticipating that the first dive of the day in Cozumel may be at a depth greater than the MOD for EAN 32% so we were planning on diving air. Then we are assuming that there will be a very short 30 minute surface interval before the second dive, so we are planning to dive wither EAN 32% or EAN 36% to help extend our NDL time for this second dive. However, my understanding is that Suuntos really impose serious penalties on the NDL's for surface intervals shorter than 60 minutes.

My questions for Nitrox divers in Cozumel are:
1. Do people commonly dive air on the first tank and then EAN on the second tank in Cozumel? ie. Will using EAN give us a more reasonable NDL on this second dive?
2. Is yes, would you recommend diving EAN 32% or 36% giving the typical second dive profiles in Cozumel?
3. Is anyone aware of oxygen toxicity problems diving with Nitrox on the first deep dive?

My questions for those familiar with Suunto computers are :
1. Would you allow the Suunto computer to go into deco and assume it will clear as you slowly ascend (10 ft/min) with mulitlevel stops for several minutes at 50 and 40 and 30 feet?
2. If yes, what is the maximum deco obligation that you would incur (assuming, of course, that this still falls within the gas plan)?

FWIW, I did do a search on SB forum and found numerous comments condoning this type of practice to counter the overly conservative limits of the algorithm. For example, here is a quote from lamont in another thread:

"Realistically on a Suunto with 5 minutes showing (2 mins mandatory + 3 mins safety stop) you're not in much danger at all. You can probably even go across that by another 5 mins at depth and while the Suunto will probably be telling you 10+ mins of deco to do, you'd be fine blowing it off if the absolute worst case happened to you.

So yes, I realize that I have no technical training, and that I am diving a single AL80 tank, but I am also getting the impression that in the worst case scenario, it is the computer that will get bent, and the dive plan is still within safe recreational limits on pretty much any other computer.

I am hoping to get responses that will help me figure out how to best dive safely in Cozumel with our Suunto computers - and please do not suggest buying new computers is the answer!

Hi Gasgirl. I also dive a Suunto Cobra III and have used it the past two dive trips to Cozumel. I dive air on the first dive and Nitrox on the second dive each day. I have not had a problem with hitting deco prior to hitting 700 psi and going to safety stop. The past two years I have done my diving with BlueXTsea and had nice leisurely SI's. However 3 years ago I was diving air for both dives each day and was using a Suunto Gekko and did run into deco limits on the second dive about 3 days into the dive trip. The rest of that week I was spending quite a bit of time above everyone else and avoiding swim throughs by going over the top of the reef on those second dives.

Gaffer

 

[shoredivr]

Thanks for that detailed clarification, Matthew Atkins of Blue Angel. It's great to have your shop's input in this thread. Altogether a good outcome.

 

[islanddream]

Yes, that is the question I am asking to those who dive with Suuntos AND have allowed the ASC time to appear: How many minutes beforet actually incurring an extended safety stop?

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I actually have a couple of Aeris computers that are Air only that I would be better off using rather than just diving tables with the Cobras in gauge mode. However, that would limit us from using any Nitrox during this trip.

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Here is a quote from a November 2011 trip report from islanddream at the same dive op that I booked in Cozumel:

"Probably the biggest eye-opener for us were our Suunto Cobra computers! We've had them for ten years and they have worked great for the diving we've done previously. During this week we did some fairly deep dives (my max was 116') with swim-throughs, walls, etc. Our past diving history was much more conservative and our computers never put us close to deco. However, because of the profiles we were diving each day, we got very close to deco many times. What a pain to have to ascend when there were so many more swim-throughs to do! Anyhow, Jorge said it perfectly... "those computers are s--t!" And we have to agree because they are SO conservative! Like I said, they've done us well in the past, but we are now diving a much different profile."

Hi Gasgirl:

Yes, I did post how conservative our Sunntos are. I'm so happy we now only use them in the gauge mode and our new Aeris 2 as our computer. We dove in Belize a month ago and didn't have any problems getting close to deco.

Believe me, The Blue Angel dive staff take surface intervals seriously. Ours were always at least 60 minutes long. I hope my previous post didn't mislead you to think it was the dive staff's fault that we got close to deco....it absolutely wasn't. Suunto is just a very conservative computer.

Have a great time diving with the wonderful people at the BA!

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Wow, what a fantastic amount of utter tosh this thread has generated...

I've done thousands of dives with a variety of Suunto computers, along with, on occasion, Aladdins, VR3s and Uwatecs. Most of the recreational diving we do here is air to around 100-120 feet max depth, multi-level profile running to between 50 and 60 minutes, 90 minute SI, then repeat. Never had a problem using a Suunto D6, a Gekko (or a Zoop, which is the same computer), or a Vyper.

The answer to your question is to refuse to dive with anyone who expects you to dive 30 minutes after a 100 foot dive. That simple. DMs/guides who say 'Suuntos are rubbish, they're too conservative' are ACTUALLY saying 'I don't give a rat's ass about your safety, but I do want to get home and get rid of you tourists as early as possible'. They probably also think that diving 'aggressive' profiles makes them more manly in some way.

Yes, sometimes, if you jump in for a second dive after a short SI, a Suunto computer will reduce your no-deco time. It will also reduce your no-deco time if you ascend too fast. And if you do put it into deco on a first dive, just watch the time-to-surface rack up if you put it in deco again on the second dive!

If you don't have a clear understanding of what you're doing, I'd strongly recommend NOT putting your computer into deco. Unless someone is leading you on a fairly marginal profile, there should be absolutely no need anyway.

The our DM NEVER made us feel like he didn't give a rat's ass about our safety, or that he only looked at us as tourists he wanted to get rid of so he could get home. He's the best DM we've ever dived with in Coz. Just because he felt our Suuntos were very conservative, it really doesn't translate to what you've implied. We got extremely frustrated with our computers without any input from him. Doing two dives per day for six days simply pushed the computers to their limit. Be that as it may, we always followed what the computer said for safety stops because we didn't want to get "shut out" for the 24 hours. Our SIs were always 60 minutes or longer.

 

[GrimSleeper]

The our DM NEVER made us feel like he didn't give a rat's ass about our safety, or that he only looked at us as tourists he wanted to get rid of so he could get home. He's the best DM we've ever dived with in Coz. Just because he felt our Suuntos were very conservative, it really doesn't translate to what you've implied. We got extremely frustrated with our computers without any input from him. Doing two dives per day for six days simply pushed the computers to their limit. Be that as it may, we always followed what the computer said for safety stops because we didn't want to get "shut out" for the 24 hours. Our SIs were always 60 minutes or longer.

I assumed people would take the comment about DMs saying Suuntos are too conservative in conjunction with the suggestion that the OP shouldn't dive with an operator who expected her to go back down 30 minutes after a 100 foot dive. My bad. Since you say you weren't pressured into diving on short SIs, it would appear the OP was misinformed.

FWIW, I've dived Suunto computers anything up to five times a day, deepest dive around 100 feet, for anything up to ten or twelve days in a row. Never had problems with NDLs. Currently, I regularly do two dives a day, both to around 120 feet, often for several days in a row, up to six or seven days. With Suunto computers. No problems with NDLs. And I'm often diving with people using all sorts of other computers, including those using much more aggressive algorithms. They never seem to have a problem with the profiles we do - nobody has ever suggested that I'm somehow short-changing them by not staying that extra 90 seconds at 100 feet. YMMV.

 

[Tunaman68]

Blue Angel is a wonderful dive op (I dove with them in the late 80's and then again the last couple of years), full of great people who REALLY care about their clients physically and personally both on and off the boats. Our SI has always been around 60 minutes but flexible based on where we just dove and where we were going to dive next.

We were there with Islanddream diving similar profiles and as I saw them hanging an 18 minute safety stop after the 2nd dive of the day while my oceanic was giving me 3 minutes I was glad I sold my Suuntos. Just saying.

Thanks for the reply Matt, can't wait to get down to Coz and dive with you guys again.

 

[Searcaigh]

We were there with Islanddream diving similar profiles and as I saw them hanging an 18 minute safety stop after the 2nd dive of the day while my oceanic was giving me 3 minutes I was glad I sold my Suuntos. Just saying.

This is comparing Apples with Oranges, there is insufficient information here regarding previous dives, dive profiles, gas mixes etc.

I had an instabuddy last Friday who had a 25 min deco on his second dive using a non-Suunto computer, BUT I used Nitrox on both dives and he was on air, so does that make his computer rubbish? I think not!

 

[gasgirl]

Blue Angel is a wonderful dive op (I dove with them in the late 80's and then again the last couple of years), full of great people who REALLY care about their clients physically and personally both on and off the boats. Our SI has always been around 60 minutes but flexible based on where we just dove and where we were going to dive next.

We were there with Islanddream diving similar profiles and as I saw them hanging an 18 minute safety stop after the 2nd dive of the day while my oceanic was giving me 3 minutes I was glad I sold my Suuntos. Just saying.

Thanks for the reply Matt, can't wait to get down to Coz and dive with you guys again.

I am not trying to beat a dead horse as I have already said that I now feel completely confident I can dive safely with Blue Angel using the approach that Matt described in his post.

Appropriate dive planning along with Nitrox on the second dive should pretty well keep me from having to do that 18 minute safety stop that Tunaman68 said he witnessed.

However, I do feel I need to clear the air as I will be diving with BA in 10 more days - and I do not want that relationship to start off on the wrong fin!

First off, I never said that BA pressured anyone into diving short SI's.

What I did say in one of my posts is that I had experienced a 30 min SI in Grand Cayman.

In fact, when I was asked to name the dive op that I had booked with, I did not think it was fair to do so, until I contacted BA to find out what their SI practice actually was.

Unfortunately, the Front Reservation did not word it well - but even then I interpreted their response to mean they would do their best to accomodate my needs.

Others who read BA's email response interpreted it differently and felt I needed to get further clarification directly from Eva.

Fortunately, Matt was able to explain it much more clearly in his email, and the whole thing was resolved. All good.

So sorry, not to nitpick anyone, as I am operating on the assumption that everyone posting is really just trying to help.

But I didn't want anyone who didn't take the time to read the entire thread to get the wrong impression.

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BTW, if anyone is interested, here is a link to a poll I started in the Cozumel forum:

http://www.scubaboard.com/forums/co...ace-interval-two-tank-boat-dives-cozumel.html

I am happy to report that , so far, no one who responded has had a 30-40 minute SI in Cozumel!

 

[Searcaigh]

Hope you have a great trip gasgirl