Negative entry vs Using a downline

[danvolker]

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A ScubaBoard Staff Message...

off topic posts split by bowlofpetunias from http://www.scubaboard.com/forums/ac...cued-near-san-clemente-island-california.html

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I think we;re supposed to have SOME air in the BC but not full when jumping in, right? (Due to the need to keep sudden pressure in the BC under control to avoid a BC or valve failure?)

Jeezzz....GREAT job on the rescue, Bill (and others)! You sure seem to have had your wits about you in a stressful circumstance.

- Bill

An advanced diver should not be forced to jump in with a bouyant BC..the idea is to go right down, not to float on the surface like a duck, and allow whatever current there is to blow you off the desired drop site.
All divers DO need to jump in with reg in mouth though.

If this was a novice diver, then yes, maybe she would have been better off fully inflated prior to jumping in....Though at this juncture...do we even know for sure that she went in on purpose, or fell in and was unprepared and negative without reg...and panicked.....or , was she even conscious when she hit the water ? Maybe she had had some sort of medical event and this caused a black out and fall....We need to know a lot more or it would be hard to even call it speculating

 

[Hatul]

An advanced diver should not be forced to jump in with a bouyant BC..the idea is to go right down, not to float on the surface like a duck, and allow whatever current there is to blow you off the desired drop site.
All divers DO need to jump in with reg in mouth though.

If this was a novice diver, then yes, maybe she would have been better off fully inflated prior to jumping in....Though at this juncture...do we even know for sure that she went in on purpose, or fell in and was unprepared and negative without reg...and panicked.....or , was she even conscious when she hit the water ? Maybe she had had some sort of medical event and this caused a black out and fall....We need to know a lot more or it would be hard to even call it speculating

If there is a current, the prudent thing is descend holding onto a line rather than jumping in to make blue water descent. Personally I'd be very reluctant to follow your method. Besides finding an equipment issue at depth, you run the risk of buddy separation.

 

[danvolker]

If there is a current, the prudent thing is descend holding onto a line rather than jumping in to make blue water descent. Personally I'd be very reluctant to follow your method. Besides finding an equipment issue at depth, you run the risk of buddy separation.

It's all in the training.....I dive an area where 2 to 4 mph currents are common, and we do negative entries. This is drift diving, and the cool thing about this, is that you actually do much less work with this.....For a 2 mph current, go down hand over hand on a line, and you blow lots of air fighting the current on the descent.
With the negative drift drop, the boat drops you 100 feet up current of where we want to end up, and you jump in, and do a leisurely swim down....i Might not need more than 3 breaths to reach 70 feet....whereas a guy hand over hand on a line might burn 500 psi to reach 70 feet.

The whole line descent and ascent thing is really a defective way to dive--once you have experienced how much easier Palm Beach style drift diving is....And I do mean EASIER.

Buddies go down with eye contact beginning the moment the bubbles clear from jumping in....you get side by side as you swim down, and the buddy team descends at the pace comfortable for the team. Gear---it is checked at the surface, before you jump in.....Each buddy is watching the other on descent...at the bottom, if you want to do more checks you can do it there, out of the current ( skin friction drag on the bottom, horizontal and belly to the bottom--5 inches off the bottom

 

[DandyDon]

An advanced diver should not be forced to jump in with a bouyant BC..the idea is to go right down, not to float on the surface like a duck, and allow whatever current there is to blow you off the desired drop site.
All divers DO need to jump in with reg in mouth though.

If this was a novice diver, then yes, maybe she would have been better off fully inflated prior to jumping in....Though at this juncture...do we even know for sure that she went in on purpose, or fell in and was unprepared and negative without reg...and panicked.....or , was she even conscious when she hit the water ? Maybe she had had some sort of medical event and this caused a black out and fall....We need to know a lot more or it would be hard to even call it speculating

Yep, like on many Cozumel dives, we go in with empty BCs so we can get down as fast as possible in the usual current, except my bud has to stop around 15 ft down to work his ears which can be a challenge as the 15 ft current might be blowing us off the site - but we do what we have to do. I always stay with him while he works thru equalizing, committed to our enter, descend, stay, ascend, exit together agreement. We just don't know if she went in without her bud on purpose or fell in for some reason, and I doubt she remembers. Some divers who have difficulties descending also have buddies who say "meet you on the bottom," which is dangerous.

With regard to "sudden pressure in the BC under control to avoid a BC or valve failure," we try to keep our gear in good shape and test our BCs against over filling everyday before dives. When I jumped into The Pit at Dos Ojos, it was a hell of a drop to the surface - not sure how far, but I had my tested BC pretty full and tightly secured. It may well have burped as I still sunk a bit on impact.

 

[scubafanatic]

Yep, like on many Cozumel dives, we go in with empty BCs so we can get down as fast as possible in the usual current, except my bud has to stop around 15 ft down to work his ears which can be a challenge as the 15 ft current might be blowing us off the site - but we do what we have to do. I always stay with him while he works thru equalizing, committed to our enter, descend, stay, ascend, exit together agreement. We just don't know if she went in without her bud on purpose or fell in for some reason, and I doubt she remembers. Some divers who have difficulties descending also have buddies who say "meet you on the bottom," which is dangerous.

With regard to "sudden pressure in the BC under control to avoid a BC or valve failure," we try to keep our gear in good shape and test our BCs against over filling everyday before dives. When I jumped into The Pit at Dos Ojos, it was a hell of a drop to the surface - not sure how far, but I had my tested BC pretty full and tightly secured. It may well have burped as I still sunk a bit on impact.

I'm not a fan of the negative-entry 'crash dive', unlike a U-boat, humans HAVE eardrums, and jacking up ones eardrums is an excellent way to trash an anxiously-awaited (and potentially spendy) dive vacation! No need to crash-dives with an intelligent dive plan, it's easy to adjust the glide path to intercept the UW 'target' without doing a vertical drop !

 

[DandyDon]

I'm not a fan of the negative-entry 'crash dive', unlike a U-boat, humans HAVE eardrums, and jacking up ones eardrums is an excellent way to trash an anxiously-awaited (and potentially spendy) dive vacation! No need to crash-dives with an intelligent dive plan, it's easy to adjust the glide path to intercept the UW 'target' without doing a vertical drop !

Oh, I forgot to mention proper weighting. Be sure to be properly weighted so you can get down at a comfortable rate, but avoid overweighted, negative-entry sinking. Ear clearing early & often is always a good idea. My bud & I practice before we get on the boat, on the way out, and certainly right before entering water. Actually he has to do exercises for days in advance, but we always take it slow with the 10-15 ft stop to avoid injury. He finds all this easier after a few days of diving. I have to blow my nose frequently in life so maybe I get constant practice?

 

[danvolker]

Don's point is well made...A good diver does not carry much weight beyond what is required to become neutral---which means that will all of the air out of the BC, you are maybe 2-5 pounds heavy--certainly NOT enough to "pile-drive" you to the bottom. And you descend at a pace comfortable for BOTH buddies--that both easily equalize at.

My buddies and I have been doing this a very long time....and each of us clears fast enough for any descent speed.

Here is a site that did require a fast descent..
[video=youtube_share;qeQp5aqy2_s]http://youtu.be/qeQp5aqy2_s?t=7m36s[/video]

If this does not cue up like it is supposed to, please pull the cursor under the video to ___ 7 minutes and 36 seconds____ "in" to the video

...the beginning of the morning dive AFTER the Goliath Spawn in Jupiter.


What you will see is an advanced dive site, with about 60 massive Goliath Groupers around, and some amazing sights.....This is a wreck dive, and the current was running around 4mph or FASTER....Which you can see from the way the jewfish are swimming sideways along the current--they get blown around too ..., and you can see my wife /dive buddy Sandra with her big camera, getting low and "out of the current" by getting close to the bottom and behind a structure, so that she could compose shots.....If she did not know about currents--was just a still water photographer, she would have been hanging about 10 feet off the bottom on this 100 foot deep dive, and this would have then been a video of her being blown away like a leaf in a wind storm.
Equally key, is that our descents with a current like this, were strategically planned by the boat captain ( the individual with the REAL SKILLS that are most key to this drift diving--the Captain is the key) -- the Captain dropped us the distance UPCURRENT of the wreck, that he thought it would take Sandra, Jim Abernethy, Bill Mee, and myself, to reach the bottom at 100 feet.....In our case, Sandra needs the first 15 feet a little slower, but by 15 feet her ears are well opened, and she can then descend at any speed like the rest of us...so the captain estimated we needed about 100 to 150 feet of up current distance ( Bill, Jimmy and I can drop at 300 or 400 per minute if we want---I shoot with a Gavin Scooter and Canon 5D mounted to it....If I run straight down with scooter at full speed, and I am kicking, I can get to the bottom at ridiculous speeds--when I do this, I am pretty much squeezing and blowing into my nose the whole way down...)

The captain drops groups or 4 , and does multiple drops....and has fast droppers, medium drop speed divers, and slow droppers....The slower ones get dropped maybe 400 feet or further up current of the drop site, and they just take their tme in reaching the bottom, and then when they reach it, all of a sudden the ship suddenly appears and "comes to them".... The advantage of our faster drop, is that we can specify that we want to intersect the shipwreck at one end or the other, or right by a specific structure maybe only 15 feet in size--on a wreck around 300 or so feet long.....we can get pin-pointed, the slow descenders just take what they can get
Also, we don't waste ANY gas in travel in areas we don't want to shoot photos in---no wasted time on a long drift in to the wreck....

All this gets exaggerated more on our deeper and more challenging deep reefs or wrecks.....This is a place to go when you want to see the ocean eco-system the way it used to be in many other places 1000 years ago before chronic overfishing.

 

[T.C.]

An advanced diver should not be forced to jump in with a bouyant BC..the idea is to go right down, not to float on the surface like a duck, and allow whatever current there is to blow you off the desired drop site.

That's great for Florida. Ever consider that not everyone dives there?

Didn't think so.

In most cases, partially inflated BCDs are safer. And if there is a descent line, it is FAR safer and easier to drop down that line.

The only thing "defective" is your advising that it is better. It is not. It is less safe and presents far more problems, ranging from equipment issues (easily resolved by simply going up the line, or holding in place), buddy separation (you're both on the line, seperation risk is low), or medical problems (you can halt to clear your ears on a line and still not miss the site).

It may work where you're from, but it often isn't the case.

And thinking you'll burn more air on a line is silly. You'll burn the same amount as any other diver descending at the same rate.

 

[danvolker]

That's great for Florida. Ever consider that not everyone dives there?

Didn't think so.

In most cases, partially inflated BCDs are safer. And if there is a descent line, it is FAR safer and easier to drop down that line.

The only thing "defective" is your advising that it is better. It is not. It is less safe and presents far more problems, ranging from equipment issues (easily resolved by simply going up the line, or holding in place), buddy separation (you're both on the line, seperation risk is low), or medical problems (you can halt to clear your ears on a line and still not miss the site).

It may work where you're from, but it often isn't the case.

And thinking you'll burn more air on a line is silly. You'll burn the same amount as any other diver descending at the same rate.

I have dived all over the Caribean, I have dived Fiji, and cold water sites like the Great Lakes, Catalina and Farnsworth Banks.....
There is not one single place I could imagine wanting to dive at, where the use of a line for ascents and descents is not defective ( I am excluding all under Ice dives .....I see descent/ascent lines as the domain of lazy captains that don't want to learn drift proceedures. **** We have plenty of days with zero current--and when this happens, the dives are still far superior without the nonsense of the lines.... If you had to do a wreck in 10 foot vis or less... I suppose that is an argument FOR the lines....but not a good one....

The only diver I see benefiting from the lines method, is the diver with poor equalization abilities.....for them this really may be their only way of not missing the target.

On a liveaboard in the Carribean, the boat will often anchor and you are free to dive in the no current area as far away as you would like....this means you can ignore the anchor line, and at the end of your dive, if along way away, you can snorkel back...or, you can have navigated back to the liveaboard u/w.....but use of the lines for going up or down is not relevant to diving on a big liveaboard. It is just the way they need to deal with such a large boat, and divers that are doing 6 dives per day..and getting in and out at all times.

As to the burning air issue.....We have a wreck called the Castor that some divers will opt to use a line on, because it is 110 feet deep, and they like the line for keeping their group together on ascent and at stops.... However, there is usually enough current on this wreck that pulling down the line becomes an arm workout.....you are fighting hard enough to hang on, that it is a lot like being on monkey bars.....for 100 feet. And....this hand over hand descent is slow....it will take several minutes for most divers to get down like this--whereas when we dive this wreck, the Captain drops us about 200 feet up current of it, and 30 seconds of easy swim-assisted falling later, we are on exactly the part of the wreck we want to be on...and we would see the line pulling divers a few minutes later..and they will have used up a significant amount of air getting down to the wreck that we did not....

The Castor...
[video=youtube_share;PIaXVw61qJI]http://youtu.be/PIaXVw61qJI[/video]
Whether we have 100 foot vis, or if it was after a storm and the vis was only 10 feet, this is ideally a negative entry, drift drop....whether there is current or not !

And another thing! Why in the world would you WANT to only get half of an exploring dive.....half, because at the half way point, you would have to turn around and go back the way you came--this 2nd half being wasted when you really want to spend every moment seeing more new structures....if you don't have to return the way you came to a line...if you could just go as far as you wanted, then come up where you wanted--wouldn't that be better?


Once you experienced how easy this style of drift dropping is, you would DEMAND this of any boat you chartered.....And when I leave florida on Vacations elsewhere....I bring my inflatable torpedo float, that the boat follows on drift dives.
Visit Palm Beach and I would be happy to convert you to this "dark side"....

 

[T.C.]

I have dived all over the Caribean, I have dived Fiji, and cold water sites like the Great Lakes, Catalina and Farnsworth Banks.....
There is not one single place I could imagine wanting to dive at, where the use of a line for ascents and descents is not defective ( I am excluding all under Ice dives

Wow....egostical much? Your way works good for just one type of dive. A drift dive. Any other type, it's unnecessary. Too bad you can't see this.

The only diver that you see benefits is "poor equalization"? Really? You've never seen a gear problem develop? Never seen a diver make it halfway and not be able to equalize? Never seen a buddy team, even using the best procedures, get separated?

Noooo....this never happens to you, does it? We get it, you think your diving is best, but there's a whole world out there that disagrees with you.

My point is simple. Entering negative may have it's place and time, but we don't know if this was one of them. If it wasn't a designed drift dive, entering postively bouyant is safer and far better.

Visit Palm Beach and I would be happy to convert you to this "dark side"....

I'm going down there Easter weekend. But I deem you reckless and unsafe (as well as annoying) and I wouldn't want to dive with you.

---------- Post added March 30th, 2014 at 04:47 PM ----------

I appreciate everyone's comments regarding this incident.

One point of clarification: Witness statements, though collected afterward, did not accompany the victim onto the chopper. What DID accompany her was the timeline. A rescue-trained passenger saw that many other people were scrambling to attend to the essentials (CPR, assembling O2 kit, getting the AED, etc) and began writing down a timeline of what was done beginning with the victim being brought aboard the boat. This person wrote down what he was observing, important info I passed to him during and after CPR, and as much of the victim's info as we could gather up. This timeline and info sheet(s) was sealed in a freezer bag and passed to the Coast Guard rescuer, along with the victim's dive computer and overnight bag.

Most (if not all) of the witness statements were collected by the boat captain and used in his interview with the Coast Guard some days later.



Bill Powers

Still, the presence of mind to start a timeline, and to realize that this is the best way to help is remarkable. Most divers would want to cluster around, try to help, and get in the way. It speaks volumes of your club.