Is this a Bad Dive Plan for Cozumel?

[-hh]

...
If I had it to do over, would I post this thread again - yes, because of responses like the one from -hh!!!

My pleasure.

Thanks, Don. I doubt this will be my lifetime, dream computer but it was cheap and simple. It's fine for now. Simple is good for me. Although, I wish I had gotten a model that would download to my computer. But, for $200 what can I expect? ...

Well, you could expect to ask your hubby for a Sensus Ultra from ReefNet. Sure, at $200 (+$50) for a "just a data logger", it does seem a bit expensive, but they last forever. I have the prior "Sensus Pro" (Second Generation) design and it is ten years old and counting...and still on its original battery(!)

And I now have ten years worth of dive profiles all stored in the same data format, which is where a stand-alone device like this is nice, because it won't change if .. sorry, WHEN! .. you eventually move to a different dive computer (especially different brand). Plus, Les Wilk did a nice job in writing the software: not only can you change settings on the Sensus (time intervals), but you're able to export out every datapoint for you to use however you want (Excel spreadsheet, etc).


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Finally, one more thing, since this is on the Advanced Forum:

The question of performing Deco for Recreational diving is often a topic that generates some heat. The simple reality is that deco used to be part of rec dive training, but got "simplified" out over the years. For the doubters, here's a 30 year old PADI dive table:

And similarly, there's also been a lot of research .. and heat .. regarding the question of risk per dive for various No-Deco profiles and the like. There's no doubt that current no-stop limits as have been implemented in tables and dive computer software has undergone a lot of scrutiny - - and massaging - - based on various statistical criteria .. 1 bent per 1,000 dives, per 5,000 dives, or 1 lawsuit per 10,000 units sold (that's the liability lawyers' flavor of statistics).

To this end, I'm providing one more document that is to be used with extreme care and due diligence. This is the next-to-impossible-to-find US Navy "Risk" dive table that was published in some research 20+ years ago. FYI, the original format was text-based EPS ('Encapsulated PostScript' printer drawing commands), a now-obsolete format which I've converted to be a PDF.

Please do NOT get yourself in trouble with this table - - it is poorly labeled and potentially very misleading. The unlabeled lines are as follows: the middle curve is the PADI table of the day (ie, the above), which as one can plainly see has No-Stop times greater than what we typically accept today. The dotted line below represents the no-stop for an estimated 1% DCS risk ... and the top dashed line represents an estimated 5% DCS risk.

The reason I provide this info, despite these reservations, is because the underlying insight is still somewhat helpful for those "everything gone bad" dives to try to assess risk. For example, if one has just done a 100fsw max multilevel profile for 45 minutes and the dive computer's showing some light deco, but something happens which prevents that indicated deco from being completed, this research suggests that there's probably around a 95% chance that you're not going to get seriously bent. Hopefully, having such insight can minimize the risk of a bad situation from getting compounded into something worse due to not knowing what the magnitude of risk was.

Safe diving,

-hh

 

[scubadada]

Hi Hugh,

Thanks for supplying the Navy risk table. As another old-timer into his 4th decade of diving, I very much appreciate the historical perspective and the insight it gives into contemporary times. I've gone from Navy tables, a single 2nd, and a J-valve to today's standard. Understanding where you've been is useful in appreciating where you are now.

Good diving, Craig

 

[Tunaman68]

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!

Fair enough - we dove similar profiles as them over several consecutive days all on air. As me and my buddy are good on air, our available dive time actually kept us in the water longer on most dives. Most days, my buddy and I were doing an additional two tank afternoon/night trip however on one particular deep dive the maximum depth and time stayed there for Island dream was deeper and longer than mine by several feet for a couple of minutes. In addition, I know the Suuntos (from personal experience on around 100 dives with a Cobra 2 in many different locations and conditions) tend to ding you for fast ascents (even up and over the coral not forgot to empty my BC and now I'm at 10 feet) and then shorten your repetitive dives accordingly. No two divers are ever perfectly matched in style, skill, or behavior in the water - I was just trying to give a helpful real world example of my experiences.

The Suuntos are wonderful, reliable computers, but for ME, I find them too conservative for MY style of diving which I believe to be safe and not reckless or overly aggressive in any way.

Others experiences and opinions may differ.

 

[islanddream]

Fair enough - we dove similar profiles as them over several consecutive days all on air. As me and my buddy are good on air, our available dive time actually kept us in the water longer on most dives. Most days, my buddy and I were doing an additional two tank afternoon/night trip however on one particular deep dive the maximum depth and time stayed there for Island dream was deeper and longer than mine by several feet for a couple of minutes. In addition, I know the Suuntos (from personal experience on around 100 dives with a Cobra 2 in many different locations and conditions) tend to ding you for fast ascents (even up and over the coral not forgot to empty my BC and now I'm at 10 feet) and then shorten your repetitive dives accordingly. No two divers are ever perfectly matched in style, skill, or behavior in the water - I was just trying to give a helpful real world example of my experiences.

The Suuntos are wonderful, reliable computers, but for ME, I find them too conservative for MY style of diving which I believe to be safe and not reckless or overly aggressive in any way.

Others experiences and opinions may differ.

I sure wish you were diving over Thanksgiving weekend again, Tunaman68, so you could see how pleased we are with our new computers! Hopefully we will have NO 18 minute "hang time" events this year. We really appreciate all the good advice we got from all the advanced divers on the boat last year regarding computers....pros/cons.

That's what I really like about SB....people give their opinions, advice, comments, snarky prose, etc. A rational person can then take that information and do more research to make a good decision.

Gasgirl....have a wonderful time diving with The Blue Angel Resort. I hope you come back to SB and write a trip report after you return. Safe diving!

 

[ScubaTony]

I have been diving my Suunto mosquito for years here and love it. Yes it will usually be the most conservative computer on the boat but as the guide I like to know that if mine is close most likely the others I am with will be well in the green. We don't routinely plan deco time but my computer will occasionally ping into 4 or 5 mins on the second dive but I watch it pretty carefully! Especially when that lionfish is just tempting me 20 ft below at the end of the second dive! HA

 

[blue steal]

This has been a good thread, thanks gasgirl for starting it.

 

[charlesml3]

I am anticipating that the first dive of the day in Cozumel may be at a depth greater than the MOD for EAN 32%

Wait. No. Let's just stop talking about this computer or that computer. The premise of the entire question is wrong. No your first dive of the day in Cozumel will NOT be at a depth greater than the MOD of EAN 32. I have no idea how you came to that conclusion. These are coral reefs and walls. There's nothing terribly interesting below 90 feet which is well within the MOD of EAN 32, Cozumel or otherwise.

Stop worrying. Start diving. Do the entire week on EAN 32 if you like. You'll get great bottom times and never come close to your NDL.

-Charles

 

[Mr Carcharodon]

your first dive of the day in Cozumel will NOT be at a depth greater than the MOD of EAN 32.-Charles

Maracaibo wall, Punta Sur and Santa Rosa wall all go past recreational depths, certainly no place for EAN32. Of course one can chose to stay shallow on these dives or pick sites that are all shallow. That said the boats often decide the morning of the dive where they are going so planning is not always easy unless you and your buddy will break from the group. And since you are supposed to be with a DM while in the park that is not always an easy option.

 

[charlesml3]

Maracaibo wall, Punta Sur and Santa Rosa wall all go past recreational depths, certainly no place for EAN32.

Those are advanced dives and you should not be diving beyond your training, experience, and comfort level. I'd expect anyone diving to those depths to know how to handle that situation.

The OP was suggesting that every first dive of the day would be beyond the MOD for EAN 32. That is not the case (and I'm pretty sure you knew that).

I've been diving Cozumel for more than 13 years and never, ever heard a DM tell a diver they could NOT choose to stay at the top of the wall or avoid the swimthroughs if they so chose.

-Charles

 

[DandyDon]

It's challenging to read thru 90 replies already posted when you arrive to a thread long done, huh...?

If I were you, I would just spend a little money and get a different computer. I remember reading a story not too long ago on the Cozumel thread about how the dm for blue angel told people to toss their suunto's in the trash because they were just too limiting.

Here.. for $200 you can get this aeris wrist computer that does nitrox, too.

Aeris XR1 NX Wrist Computer


Then throw in an spg for like $80 and you are good to go.

Cressi Mini SPG (Imperial)

I'd rather spend $280 for a better rig and not guess or worry about being in deco or not.

I did want to come back and look for this link tho. That computer doesn't seem to have download capabilities, only stores 12 dives, doesn't seem to have an alarm, and may lack some other features I like on my Versa Pro and VEO, but still - a good one for someone diving without one because they didn't want to spend $300 or more. Oceanic has a nice replacement program if I ruin another one, but if I were to lose one - I might go for this for my back up. Lots of places are offering it for $200 & free shipping, some even less: $180 at Aeris XR-1 Scuba Diving Wrist Computer XR1 Dive - Sale : House of Scuba

I guess that 30 day Satisfaction guarantee is good for after diving it on a trip even...?

I get the batteries on Ebay for like 50c, O-rings if needed at hardware store, and of course I have silicone grease. Not sure if this one includes a tool? Plumbers and many handymen have tools that will do the job, but it's nice to have the special tool on a trip.