Deadly Down Current
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Looks like CD nailed it, Dadvocate.
EasyTide - on-line tidal predictions from the UKHO has info for tide charts for lots of ports around the world.
Worth noting though you cant just pick the nearest and predict slack water and so on - even areas only a few miles apart can differ in slack water time by a few hours.
For things like downcurrents which can also depend on bottom topography, wind direction and so on you really cant beat local knowledge.
Worth noting though you cant just pick the nearest and predict slack water and so on - even areas only a few miles apart can differ in slack water time by a few hours.
For things like downcurrents which can also depend on bottom topography, wind direction and so on you really cant beat local knowledge.
dadvocate,
Pagasa handles all the tide forecasts in the PI:
PAGASA - DOST - DOST SERVICE INSTITUTES
I haven't checked the tides in over a year so I am unsure where they hid it on the site. If you search for Axua's or my posts in the PPD forum you might pull up some old links we used to post. they have tidal stations all over the Philippines and are very accurate.
Canyons is located at the pinnacle of PG. There are two main currents that move across PG - the main current which follows the Batangas channel currents and a counter current that is part of a large eddy formation. The currents are subject to tides (the only time I have dove Canyons was during a slack tide).
It is no surprise that the dive sites in the area (mainly Anilao, Verde, PG, Maricaban) have rough currents. The Batangas Channel is one is the fastest moving currents in the Philippines. It's one of the main corridors the South China Sea uses to enter the inner waters of the Philippines (or innerwaters into the South China Sea depending on the season).
Hope that helps.
Pagasa handles all the tide forecasts in the PI:
PAGASA - DOST - DOST SERVICE INSTITUTES
I haven't checked the tides in over a year so I am unsure where they hid it on the site. If you search for Axua's or my posts in the PPD forum you might pull up some old links we used to post. they have tidal stations all over the Philippines and are very accurate.
Canyons is located at the pinnacle of PG. There are two main currents that move across PG - the main current which follows the Batangas channel currents and a counter current that is part of a large eddy formation. The currents are subject to tides (the only time I have dove Canyons was during a slack tide).
It is no surprise that the dive sites in the area (mainly Anilao, Verde, PG, Maricaban) have rough currents. The Batangas Channel is one is the fastest moving currents in the Philippines. It's one of the main corridors the South China Sea uses to enter the inner waters of the Philippines (or innerwaters into the South China Sea depending on the season).
Hope that helps.
Mike Juren
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I have dove the Canyons on several occassions. Here are my two bits/answers to your stories.
I am wondering if you were using local divemasters to start off with, I mean people who actually KNOW and dove the sites many times. Our divemaster Rico from Scubaplus has done several hundred dives in the Canyons, and I think that is an absolute must to start off with, to have someone who knows what can happen at any given site. We have dove the Canyons with him on several occassions with NO current at all. There are tide and current charts available for anywhere on the planet...
But we also dove the Canyons in strong current. The thing is that we knew ahead of time that there will be a current, and a downwelling and PREPARED for it. Although we had single cylinders with air (120's/NO nitrox due to the possibility of being temporarilly being dragged down), we also all had 75lbs. lift tech BCD's, and 19 cu. ft. pony bottles. If there is a possibility of being dragged down below 130', you want to have (at least one) extra high performance regulator. We also had 75 lbs. lift bags, and safety sausages.
As it happens, the dive went just like we expected. We hopped into the water, went down past the shark cave down to 140' to see the soft corals, and then we got to the 'fish bowl' , a small crater like place in the bottom (the trevallis, tuna etc. are really worth this dive) for about 8 minutes. The current above you is strong, no question about it, but that's where the big fish hang about.
Upon leaving the fish bowl, the current picks you up immediately and there is ALWAYS a downwelling (you should always find out about a dive site from local, knowledgeble divers). We inflated our BCD's to about the right buyoancy, but this is sometimes very hard to estimate as the current tosses you around pretty good, and you must keep an eye on your computer, but above all you must remain calm and composed. The bottom drops off rapidly, and the downwelling stops once you get to 100' or so (it follows the bottom). We then deployed our lift bags and did staged deco stops, first hanging around at 70' for 2 minutes (new recommeded deep stops are at least 1 minute at half of your maximum depth), then did another stop at 35' for a minute, and then 12 minutes at 15'. I had atually had to switch to my pony (nobody's perfect!) to finish my required deco as I "ran out of air" at 15' with only 200 psi remaining, so doing this dive with a small BCD and a single 80 cu. ft. cylinder is really ill conceived, and any competent dive master or operation should not have taken you for this dive.....
As for dumping weights, this is always a bad idea on a dive such as this one because you can also get a huge uplift by the current and without weights you'd op to the surface real fast from great depths, a dire consequence likely resulting from this. (this is hard to answer, because if you are still getting pulled down with a fully inflated small BCD you might not have an alternative, hence the lift bag...properly equipped with a dump valve and a proper quick disconnect clip).
Hope this help a little. All of this equipment is easy to carry and is esy to use, (try it first a few times at 40', so you get a feel for the reel).
I guess what I am trying to get across, is no matter how good you are and how experienced, it is always very wise to seek local knowledge anywhere in the world of any particular dive site (internet is great as well!), so that you can decide in advance if you are up to such a dive, and if you are, are you equipped properly for such a dive. Ultimately you alone are responsible for your safety. And let me tell you, Rico went with us, plus other divers as I mentioned, and in the current we got so badly separated that I was hanging on my lift bag for over 1/2 hr. while seeing no one. Nobody could really help me if I was in trouble. It is definitely an advanced dive. We all surfaced more or less together and deployed out lift bags and sausages on the surface, and the boat which was following our bubbles picked us all up one by one. Your buddy locking with you arm in arm did just the right thing since you were able to do it, and thanks to his calmness and experince things worked out very well. This is sometimes difficult, because if you have a panicking diver hanging onto you in current, and the panicked diver wants to get to the surface, you have to dump air (thank God you still have your weights) to counter his buyancy while trying to calm him down and trying to regain control of the dive.
But that would be another story...
Regards, Mike
I am wondering if you were using local divemasters to start off with, I mean people who actually KNOW and dove the sites many times. Our divemaster Rico from Scubaplus has done several hundred dives in the Canyons, and I think that is an absolute must to start off with, to have someone who knows what can happen at any given site. We have dove the Canyons with him on several occassions with NO current at all. There are tide and current charts available for anywhere on the planet...
But we also dove the Canyons in strong current. The thing is that we knew ahead of time that there will be a current, and a downwelling and PREPARED for it. Although we had single cylinders with air (120's/NO nitrox due to the possibility of being temporarilly being dragged down), we also all had 75lbs. lift tech BCD's, and 19 cu. ft. pony bottles. If there is a possibility of being dragged down below 130', you want to have (at least one) extra high performance regulator. We also had 75 lbs. lift bags, and safety sausages.
As it happens, the dive went just like we expected. We hopped into the water, went down past the shark cave down to 140' to see the soft corals, and then we got to the 'fish bowl' , a small crater like place in the bottom (the trevallis, tuna etc. are really worth this dive) for about 8 minutes. The current above you is strong, no question about it, but that's where the big fish hang about.
Upon leaving the fish bowl, the current picks you up immediately and there is ALWAYS a downwelling (you should always find out about a dive site from local, knowledgeble divers). We inflated our BCD's to about the right buyoancy, but this is sometimes very hard to estimate as the current tosses you around pretty good, and you must keep an eye on your computer, but above all you must remain calm and composed. The bottom drops off rapidly, and the downwelling stops once you get to 100' or so (it follows the bottom). We then deployed our lift bags and did staged deco stops, first hanging around at 70' for 2 minutes (new recommeded deep stops are at least 1 minute at half of your maximum depth), then did another stop at 35' for a minute, and then 12 minutes at 15'. I had atually had to switch to my pony (nobody's perfect!) to finish my required deco as I "ran out of air" at 15' with only 200 psi remaining, so doing this dive with a small BCD and a single 80 cu. ft. cylinder is really ill conceived, and any competent dive master or operation should not have taken you for this dive.....
As for dumping weights, this is always a bad idea on a dive such as this one because you can also get a huge uplift by the current and without weights you'd op to the surface real fast from great depths, a dire consequence likely resulting from this. (this is hard to answer, because if you are still getting pulled down with a fully inflated small BCD you might not have an alternative, hence the lift bag...properly equipped with a dump valve and a proper quick disconnect clip).
Hope this help a little. All of this equipment is easy to carry and is esy to use, (try it first a few times at 40', so you get a feel for the reel).
I guess what I am trying to get across, is no matter how good you are and how experienced, it is always very wise to seek local knowledge anywhere in the world of any particular dive site (internet is great as well!), so that you can decide in advance if you are up to such a dive, and if you are, are you equipped properly for such a dive. Ultimately you alone are responsible for your safety. And let me tell you, Rico went with us, plus other divers as I mentioned, and in the current we got so badly separated that I was hanging on my lift bag for over 1/2 hr. while seeing no one. Nobody could really help me if I was in trouble. It is definitely an advanced dive. We all surfaced more or less together and deployed out lift bags and sausages on the surface, and the boat which was following our bubbles picked us all up one by one. Your buddy locking with you arm in arm did just the right thing since you were able to do it, and thanks to his calmness and experince things worked out very well. This is sometimes difficult, because if you have a panicking diver hanging onto you in current, and the panicked diver wants to get to the surface, you have to dump air (thank God you still have your weights) to counter his buyancy while trying to calm him down and trying to regain control of the dive.
But that would be another story...
Regards, Mike
Note that swimming against a current is harder than floating up against a downwelling. So not being able to swim against a river doesnt mean the same river could suck you down against the force of the BC, or that anything could hold you down.
I'm not saying this to start a fight, but if you had to switch to your pony bottle to finish your deco, then your dive was very ill-conceived as well. I would personally not do the type of dive you mentioned. Period.
140' is deep without current, deco, or upwellings, and putting all four together - in a single tank no less - is asking for disaster. I regularly dive with a slung 19cf pony, and I would not consider relying on it to get me to the surface below 100' in calm conditions without mandatory deco. The dive you are describing is most definitely requires doubles, and instruction in technical decompression diving. At the very least, read some of the posts on this board about Rock Bottom.
Tom
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Hey! Caca happens. It happens to some of us more than others, some of us make ourselves more vulnerable, but dives come with surprises, ok?
Hey! Caca happens. It happens to some of us more than others, some of us make ourselves more vulnerable, but dives come with surprises, ok?
I agree. Bad things do happen, and we need to allow for that by planning for it. I have absolutely no problem if someone sucks the last breath from their tanks dealing with an emergency and still makes it onto the boat. The problem is if that same person sucks their last breath while in the course of a problem-free dive, then they have absolutely no margin for error if something HAD happened on the dive. Do the math...at 140', you are at greater than 5ATA. If you're exerting yourself, you could easily pull 5cf/min from that 19cf pony at that depth. If your math comes out like mine that's not a whole lot of lee-way.
One of the smarter things I've heard from a boat captain is "use as much gas as you need to, but if you get back with less than 700psi, there should be a good reason." Its still not perfect, but its better than most rules of thumb.
Tom
Re 700psi - does he mean you should burn the extra gas doing as long a stop as you can?
Or does he mean dont thumb the dive unless you burn your air or have a huge problem because people pay money for this?
Because I consider "I dont want to dive anymore" a good enough reason.
Or does he mean dont thumb the dive unless you burn your air or have a huge problem because people pay money for this?
Because I consider "I dont want to dive anymore" a good enough reason.
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