Deep Dives

[Blasto]

Charter is the Gulf of Mexico NW FL. Offshore bridge spans and wrecks. No DM going in the water that I know of.

That should be well outside of your comfort zone - no DM, less than perfect conditions, and deep.

At 15 dives, most divers would generally stick to OWD limits. 4-6 dives outside of training is very little unsupervised experience. Essentially, whoever you're buddied with will have to act as your guide and DM - you just have to hope they're up to the task.

 

[TMHeimer]

On my very first boat charter after OW cert. I went to 78' and was buddied with the on board instructor's "very experienced" husband. At one point I was alone down there. He apologized for slipping away to catch three lobsters. You don't want that scenario at 120'.

 

[tarponchik]

I did not dive the Gulf too many times but my impression was that visibility is generally not as good as at the ocean side of Florida or in the Caribbean; to me it looked more like diving in NC (albeit much warmer). Also, the sheer density of sardine schools at some sites reduced visibility drastically. If this is true, for a newbie like you the number one priority will be not to get lost. Stay calm, keep close to your buddy or group, do not overwork your fins, check your air often and you'll be fine.

 

[Russoft]

Hello,

I have the chance to go on a charter that will be going to sites in the 90 ft to 120 ft range.

I have 15 dives total at this point (deepest was 75 ft.). I also have my AOW and Nitrox certs.

If I go on the charter, it will be luck of the draw on insta-buddies or possibly no buddy as has happened before.

Ideally, I'd like to get a AL30 pony for thus dive, but probably not in my budget right now.


Anyone have any advice whether or not diving down this deep is a good idea or not at this point in my diving career?

Perhaps, I spend too much time reading the Diving Accidents forums.

Thanks!

I survived depths like this with my Jr. OW with idiot dive ops. The key was that I was relaxed and confident in my abilities at the time. Conversely, my worst experiences on deep dives all occurred when I was feeling anxious about the dive ahead of time. If you're not comfortable diving deep, then don't. Stay within your comfort zone. Don't do "trust me" dives. That's how I've come to fully enjoy diving: by always diving within my comfort zone. Only around dive 50 did I become comfortable with more advanced/deeper dives, and that was after spending a dozen dives building self reliance through planning and leading my own dives (shallow, to 30 ft) without a DM to hold my hand. You learn your equipment, your ability to navigate, and how to deal with problems underwater.

Seriously, if you're stressed out, you aren't enjoying yourself. Spend time on some shallow reefs looking at pretty fishes. Work on your trim, buoyancy, and basic skills. Enjoy pretty reefs with lots of visibility and light. Enjoy your long bottom times despite your bad air consumption. Once you're thoroughly bored, then think about "advanced" dives. I didn't even do AOW or Nitrox until dive 45. For the first few dozen dives, the basic scuba unit was complicated enough without the added complication of a pony bottle.

 

[lowflyer]

I think with PADI your AOW deep dive just has to be over 60 feet, but not over 100 feet. Isn't that the standard?

Richard.

Yes, that's the PADI standard for the AOW Deep Adventure Dive.

 

[stuartv]

Ideally, I'd like to get a AL30 pony for thus dive, but probably not in my budget right now.

Before you spend for a 30, give some thought to a 40 instead.

They're the same diameter. The 40 is just taller. But, the 40 has better buoyancy characteristics (it's less negative, in the water, when full). And you don't notice the extra length as it's just somewhere behind you. And, well, 33% more gas... The only real downside is the 40 is roughly 3.5 # heavier, on land, comparing full to a full 30.

 

[Kevrumbo]

Hello,

I have the chance to go on a charter that will be going to sites in the 90 ft to 120 ft range.

I have 15 dives total at this point (deepest was 75 ft.). I also have my AOW and Nitrox certs.

If I go on the charter, it will be luck of the draw on insta-buddies or possibly no buddy as has happened before.

Ideally, I'd like to get a AL30 pony for thus dive, but probably not in my budget right now.

Anyone have any advice whether or not diving down this deep is a good idea or not at this point in my diving career?

Perhaps, I spend too much time reading the Diving Accidents forums.

Thanks!

Thanks for the advice. Charter is the Gulf of Mexico NW FL. Offshore bridge spans and wrecks. No DM going in the water that I know of. Guides I think are $100.

Previous dives are a mix of quarry dives with horrible viz, and a boat dive in the Gulf. IDK my exact SAC rate. On my previous boat dive to 75 ft., I managed about 25 minutes I used about 2000 psi.

Just curious if I was being overly cautious.

Rental AL 80 tanks. Which seems like it would really limit bottom time. . .

For 0.75 SAC (a reasonable nominal non-exerting SAC rate attainable for most novice divers): 300 psi per 10 mins per ATA for Al80/HP100/LP72; 200 psi per 10 mins per ATA for LP104/LP95/HP120s/HP130.

• With an AL80 at 100fsw (4 ATA) for example with a SAC of 0.75 cf/min, you will consume 1800psi in 15min of nominal non-exertion diving at depth. Assuming you have a full 3000psi cylinder starting the dive at depth, you will have 1200psi remaining at an elapsed Bottom Time of 15min (NDL time Air: 20min; NDL Eanx32: 30min).

Minimum Gas Reserve (MGR) to conservatively get two divers sharing gas in an emergency contingency to the surface from planned max depth (30fpm ascent rate to half of max depth, and then 10fpm ascent to surface, both divers breathing a stressed 1cf/min SAC rate each):
100psi per 10 fsw for LP104/LP95/HP120s/HP130, 100 psi per 10 fsw + 300 psi for Al80s/HP100s/LP72 -- 500 psi minimum for all calculations.

• With an AL80 at 100fsw, you and your buddy will need a MGR of 1300psi remaining in each of your tanks. Depending on your actual SAC rate during the dive, you may or may not have an elapsed bottom time of 15min at 100fsw before encroaching on the 1300psi MGR.

Whoever reaches MGR first calls the dive from the max working planned depth of 100fsw, and then both of you start a normal ascent to the shallower depths 60fsw and above (hopefully you'll have a colorful reef wall to look at instead of a midwater blue ascent). Plan a new MGR based on your new depth and remaining gas (example 40fsw yields a MGR of 700psi), and stay there until SPG indicates MGR for final ascent to the safety stop and the surface. . .

Lastly, if at any time at max planned depth you start exerting yourself into CO2 retention & hyperventilation, feeling "air starved" or the anxiety & dread of the "dark narc" -->stop the physical activity causing the exertion, relax and try to recover the normal deep breathing inhale/exhale cycle to purge the Carbon Dioxide build-up, and then abort the dive or ascend up to the shallows with your buddy. . .

 

[MXGratefulDiver]

Hello,

I have the chance to go on a charter that will be going to sites in the 90 ft to 120 ft range.

I have 15 dives total at this point (deepest was 75 ft.). I also have my AOW and Nitrox certs.

If I go on the charter, it will be luck of the draw on insta-buddies or possibly no buddy as has happened before.

Ideally, I'd like to get a AL30 pony for thus dive, but probably not in my budget right now.


Anyone have any advice whether or not diving down this deep is a good idea or not at this point in my diving career?

Perhaps, I spend too much time reading the Diving Accidents forums.

Thanks!

Based in the info you've provided I'd call it a very bad idea. Yes, things will probably be OK if nothing goes wrong, but diving that deep without prior experience, with someone you don't know ... or by yourself ... is cutting your safety margins very thin. It's exposing you to multiple circumstances you've yet to experience (best to expose yourself to only one new thing at a time), and I'd question whether you have adequate experience to manage the dive safely if even a small thing doesn't go exactly as planned. Furthermore, I'd ask if you have any idea to calculate your air consumption in advance, so as to know whether or not you'd even have adequate air to do a dive that deep with the tank you'll be using. I mentor a lot of new divers, and many of them would not be able to do a dive below 90 feet on an AL80 unless it was a bounce dive.

I'd highly recommend passing on that particular dive. Find something shallower. Or hire an experienced dive guide to accompany you and make sure you don't inadvertently get yourself in trouble.

Deeper dives require some extra planning and preparation ... NWGratefulDiver.com

... Bob (Grateful Diver)

 

[Tribal]

Sorry if its off-topic, but if you read a lot on this forum it looks like everyone uses a pony bottle.
Is it a American thing? I never see them in real.
Is it for when you are short on air? Or are they used like a deco bottle?

 

[Cap335]

I have done the bridge spans and they are like a wreck, you can go to the bottom or you can stay shallower on the structure and skip the deeper part if you don't feel comfortable