Negative Entries - A Bad Idea???

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During the same week of diving in S. Florida when we did the negative entry drift onto a few wrecks, we also tied in to others. Pulling ourselves down the line in a current on one wreck was a heck of an effort. And after deco on the line on the way up (using jon-lines), we noticed the current was strong enough to pull the ball under the surface. I was impressed.
 
Several thoughts come to mind after reading the very informative posts in this thread:

1. A negative entry is just that – the diver is negatively buoyant at the time they enter the eater. That doesn’t mean the diver is overweighted; rather they are properly weighted, which means they will (quite likely) be negatively buoyant at the start of the dive, with a full cylinder, and an empty BCD. BUT, if a diver is going to use a negative entry (I personally prefer them), that diver must have a very disciplined ‘checklist’ approach to gearing up and entering the water. There is no excuse for entering the water with the cylinder valve(s) turned off, or with the LPI hose not properly attached, etc., etc. Negative entries are not inherently dangerous; sloppy dive technique IS dangerous, even deadly at times.

2. Many NC coastal charter operators use what has come to be known as a Carolina Rig. But, other operators in other areas may use a similar configuration and call it something else. As enthusiastic as I am about our NC coastal diving, we don’t have a monopoly on good ideas. Under the right conditions, the rig is very functional. Nonetheless, whether the configuration is a ‘Carolina Rig’, or simply a wreck tie-in from a bow line, trying to descend to the bottom in a strong current, by pulling yourself down a line, or kicking down the line, can be exhausting (and drain a lot of air that could have been used to enjoy the wreck). In those situations, a using a ‘hot drop’, or ‘dive bombing’ the wreck, may have advantages – if the Captain knows his/her ‘stuff’; I would much prefer to let the current, and my negative buoyancy, do the work. I have dive bombed some deeper wrecks (150 – 200 ft) and completely missed them; I have dive bombed those deeper wrecks and descended smack dab onto them (or, ran into them in a couple of cases). But, when I missed them, it was usually a matter of the captain positioning me properly on the surface, but me altering my negative decent momentarily – for one reason or another - and thereby changing my glide slope.

3. Anytime there is substantial current, there is at least some risk of a group of divers becoming separated on the descent if they are not all 'connected' in some manner to a fixed down line. Those very same NC operators who regularly use a Carolina Rig also actively instruct divers to remain ‘on the line’ until they reach the wreck, when there is even a small amount of current. Frankly, they neither want nor need some divers getting pulled away and missing the wreck, by letting go of the line early, while other divers (who actually follow the instructions given in the dive briefing) end up on the wreck. If 12 divers make it to the wreck, while 4 disregard instructions, let go of the line early, and fail to descend onto it and get drawn away by the current, the crew may be faced with a situation where the four divers (having decided they missed the wreck) surface 100 yards off the wreck, and continue drifting away (of course, while waving to the boat, and wondering why the boat doesn’t come get them right then), while the 12 who followed instructions are still in the middle of their comfortable dive, swimming around the wreck, to which the boat is tied in.

One technique I have used in the case of current is to take a float ball line down with the lead (dive bomb) diver, and have all the other divers essentially dive bomb but keep in sight of the down line (the same current that affected the lead diver is affecting them, so it isn't all that hard to do). That way, all of the divers end up in the same area (even if they are all off the wreck). The boat remains unattached, and simply keeps the float ball in sight throughout the dive, AND the ascent (which is a drifting ascent). That has worked for me. But, other divers may have found better techniques.
 
One technique I have used in the case of current is to take a float ball line down with the lead (dive bomb) diver, and have all the other divers essentially dive bomb but keep in sight of the down line (the same current that affected the lead diver is affecting them, so it isn't all that hard to do). That way, all of the divers end up in the same area (even if they are all off the wreck). The boat remains unattached, and simply keeps the float ball in sight throughout the dive, AND the ascent (which is a drifting ascent). That has worked for me. But, other divers may have found better techniques.

I really like that idea - hadn't thought of something like that. May have to 'borrow in a permanent manner' (steal) and have a play with that idea. Off the face of it I can see some minor risk of self-entanglement, but practice should clear most of it. Thanks Colliam!!
 
I have used negative entries many times. In every case, it has been on a drift dive when we are doing an entry from a live boat. We needed to get to the bottom ASAP so that the group is not separated. In every case, the method has been to totally remove all air from the BCD before dropping in, and of course, making sure air is on, all hoses are connected etc. I have never seen any problem occur, but then the divers I dive with probably have an average of over 1,000 dives each. Did three negative entries last week alone when on a club dive trip to the North Solitary Island area of northern New South Wales.
 
Used this type of entry all over the world for various reasons here in California sometimes use it to punch through kelp if the boat is sitting in a patch of it you don't want to be sitting on the surface and get tangled up so you just shoot through it and meet on the bottom. We call it going in deflated just means you have no air in your BC just better have your crap together.
 
I recently came across a thread about diving in a particular location with currents where a poster stated:



Personally, I think negative entries are a bad idea, and especially when currents are involved. Using excessive weight for downward directed propulsion is going to be either ineffective, or unsafe if it's big enough to be effective. A negative entry seems to invoke too much risk when there are better ways to deal with diving in currents.

My impulse is to caution divers to think about the consequences of negative entries vs. other methods of getting down quickly. My personal preference is to dive with the ideal amount of weight (the minimum needed to be neutral at about 10 feet with an empty tank), and then kick down for a rapid descent if that is what's desired for the dive plan.

An extra 10 pounds of lead will take you down, but if you parachute drop, that 10 pounds is working against the maximum drag profile of the diver moving through the water. You won't descend nearly as fast as a diver who swims down by kicking with an average of 10 pounds thrust and is exposing a minimum cross-section and minimum drag to the water. This level of thrust is easy to produce with decent dive fins. Even a draggy diver should be able to swim in excess of 90 ft/min and a typical recreational scuba diver should be able to easily exceed 150 ft/min. That seems like a fast enough descent to me.

Also undesirable is that any extra weight carried by a diver to do a negative entry will then require the diver to inflate their BCD once down to achieve neutral buoyancy. The extra BCD inflation will then increase the diver's drag in the water making it harder for them to deal with the currents for the duration of the dive.

A diver who uses ideal weighting and swims down will have less drag and be more effective at dealing with the currents during the course of the dive. This diver is also not exposed to the risks of hitting the water negatively weighted and then potentially having to deal with another diver related problem (tank valve not open, regulator failure, BC or DS not connected, etc...) while sinking out of control.

I put the negative entry in the same category as hyperventilating when freediving. It's an idea that has the illusion of making the dive easier, but it really just adds unnecessary risks without delivering a true positive benefit.

These are my thoughts on negative entry diving and why I think it is a bad idea. Am I missing certain applications that would make the negative entry a good idea? I'd like to hear what others have to say on the subject.

Why waste all that momentum that you have jumping off a boat to come back to the surface? Why do you need to be overweighted to achieve a negative entry? You just jump or roll off, exhale and kick with your head pointed down. I'm not coming back to the surface to signal a crew member that I'm "OK" - of course I'm OK, I haven't even done anything yet.
 
I always thought "negative entry" was the way dumpsterdiver used it. Usual entry is inflated BC, do whatever you need to do on the surface, then deflate and drop. "Negative entry" is deflated from splash. I did not think "negative entry" referenced adding more weight than normal.

Although I do think operators tend to overweight divers if its a drift dive -- that is if you let them decide your weight. Last drift dive I did I asked for 12 lbs (with a 3 mm shorty), the operator insisted I use 14 lbs because it was a drift dive. As I wasnt completely sure of my weighting (hadnt been in tropical waters in a while), I gave in and accepted the extra weight. In restrospect I was probably overweighted -- hell 12 lbs is probably a bit heavy,

But, I've never heard of someone purposefullly overweighing themselves by 10 lbs!!! That's alot of weight and clearly overkill.

I agree that kicking down is a better option.

No operator is going to tell me how much weight I need. I don't care if its a drift dive or a beach dive with no current to 20fsw. Telling a certified diver how much weight to wear is so far removed from their responsibilities.
 
Why waste all that momentum that you have jumping off a boat to come back to the surface? Why do you need to be overweighted to achieve a negative entry? You just jump or roll off, exhale and kick with your head pointed down. I'm not coming back to the surface to signal a crew member that I'm "OK" - of course I'm OK, I haven't even done anything yet.
I've seen a fair number of injuries with backward rolls. Usually a newer diver bangs their head on a valve or occasionally on the hull depending on sea conditions. There's a reason that a good DM will watch you go in and watch for you to surface unless the situation requires a (briefed) departure from standard.
 

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