Negative Entries - A Bad Idea???

[scubadada]

Not sure I like all this negative talk.

I agree, a negative entry, an immediate descent, is often the best thing to do on a hot drop in current or an up current drop on a wreck., both common in SE FL

 

[KDAD]

When doing a drift dive to a wreck in a strong current your decent will be at angle. The boat captain will drop you up curent from the wreck so that as you decended you will drift with the current into the wreck. If you don't get down you may very well miss the wreck and float off in the current. At that point you will have to shoot your bouy, get picked up, and hope the captain gives you a second chance.

If you don't do a negative entry and instead linger at the surface the current will take you off of the wreck.

If you can't do a negative entry don't do the dive.

 

[Centrals]

There is absolutely no need to carry extra weight for an -ve descent. Empty bc, full tank, force of the "drop" and gravity is more than enough for me.

Is it an bad idea?
I don't do it on most of the sites but sometimes it is the only way. And if you don't like it then don't do it.

 

[REVAN]

I think the OP demonstrated a lack of knowledge and understanding of what a negitive entry is and why it's used. A demonstration of the difference between internet diving and real world experience.

There are many skills and techniques that may appear dangerous or risky, if you don't fully understand the process and reason. Often, techniques are developed to minimise risk and danger in particular environments or to solve particular problems.

Gareth

There may be a confusion of terminology here. I've gotten in the water and immediately headed for the bottom with a duck dive. I didn't consider that a negative entry. With a wet suit, I'm actually a little positive at the surface (shooting for neutral at 10 to 15 ft with an empty tank). If I drop in the water with full lungs and do nothing further, I'll stay at the surface. In my form, it takes an exhale and a duck dive to get the dive started. In that way, I'm in control of whether or not the descent commences. This is as it should be, as being out of control is something I'd consider undesirable.

My assumption was that a "negative entry" will require the diver to carry enough weight (in one form or another) to be negative upon hitting the water. It sounds like that is not necessarily the intent, but probably true in many cases as quite a few divers tend to dive over-weighted to begin with.

 

[scubadada]

You're always going to be negative at entry if you're going to be neutral at your SS

 

[Bob DBF]

My assumption was that a "negative entry" will require the diver to carry enough weight (in one form or another) to be negative upon hitting the water

If you have a full tank and empty BC you are negative when you hit the water by the weight of gas in your tank (- weight of final 500#). If I did not add air to my BC before doing a stride off a dive boat I would do a negative entry whether I wanted to or not. This would be about 5 to 8 pounds negative, depending on the tank and how full.


Bob

 

[dumpsterDiver]

The reality of the situation is that when you wear a wetsuit and you splash in, it is going to hold some air bubbles, similarly, the BC probably has some residual air as well... so I just flip over and swim down hard and not inhale completely for a while. If you were patient and waited for all the air bubbles to work out of the suit etc. then you would slowly begin too sink, but the whole idea is to hit the water and get down as quickly as is comfortable. I will expend some energy for the first 25 feet or so.

 

[REVAN]

I think, if it were called a "neutral entry", I would not have had any question on the subject. That appears to be the goal anyway (hit the water ready to dive, not ready to sink without command).

Calling it a neutral entry would reinforce that the goal is not to be too heavy at splash-in. A diver with big tanks, who sucks all the air out of the BC prior to entry, could easily get too negative to arrest the descent in an emergency. For example, twin 120s would be holding over 15 pounds of air. Add to that the loss of buoyancy from the suit that will happen by the time a diver realizes there is an issue, and it could be too late to recover without dropping lead (which seems to not happen in some cases and for mysterious reasons). So, there are circumstances where a diver would do better to not remove all the air from the BC, but to aim for being close to neutral. Neutral may require having a measured amount of lift in the BC at the start of the dive.

It's too bad that the term "neutral entry" has little chance of catching on, but it would be good if it did.

 

[Steelyeyes]

When doing a drift dive to a wreck in a strong current your decent will be at angle. The boat captain will drop you up curent from the wreck so that as you decended you will drift with the current into the wreck. If you don't get down you may very well miss the wreck and float off in the current. At that point you will have to shoot your bouy, get picked up, and hope the captain gives you a second chance.

If you don't do a negative entry and instead linger at the surface the current will take you off of the wreck.

If you can't do a negative entry don't do the dive.

That's pretty much the process we followed when we dove the Bianca C in Grenada. We fully checked out our gear (as usual) to make sure tanks were fully on, all air sources worked and BCs inflated properly. Then we emptied our BCs and when the boat captain signaled we rolled off of the boat, checked each other OK at 20 feet or so and descended about as fast as we could swim vertically downward to the stern of the wreck. It was a pretty interesting process.

 

[stuartv]

I think, if it were called a "neutral entry", I would not have had any question on the subject. That appears to be the goal anyway (hit the water ready to dive, not ready to sink without command).

Calling it a neutral entry would reinforce that the goal is not to be too heavy at splash-in. A diver with big tanks, who sucks all the air out of the BC prior to entry, could easily get too negative to arrest the descent in an emergency. For example, twin 120s would be holding over 15 pounds of air. Add to that the loss of buoyancy from the suit that will happen by the time a diver realizes there is an issue, and it could be too late to recover without dropping lead (which seems to not happen in some cases and for mysterious reasons). So, there are circumstances where a diver would do better to not remove all the air from the BC, but to aim for being close to neutral. Neutral may require having a measured amount of lift in the BC at the start of the dive.

It's too bad that the term "neutral entry" has little chance of catching on, but it would be good if it did.

First, if you get in with an empty BC, making you anywhere from 6 to 20 # or more negative (depending on how much gas you're carrying), then you have entered with negative buoyancy. Thus, negative entry seems like the correct term.

Second, I dive with double steel 120s all the time. I do a negative entry often. An uncontrolled and uncontrollable descent is not a concern - unless my BC inflator pulls off my wing or something like that (which concern is why I generally dive dry when using my doubles).