I agree with gedunk. Trim and buoyancy are related but still mutually exclusive. You can have one without the other.
Phil
accident rate without supervisors
- Thread starter MikeFerrara
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I agree with gedunk. Trim and buoyancy are related but still mutually exclusive. You can have one without the other.
Phil
They are probably OK while with the DM. The biggest problem is when they get back to a quarry or lake and say to themselves that they have been that deep before and if it was dangerous the DM wouldn't have taken them there so it must be no big deal.
As has been pointed out many times before 100 ft in the clear warm water is different than 100 ft in a cold quarry.
Chad
OP
Questions...
If trimmed head up what state of buoyancy is required to move foreward? Ill answer...one must be negative or they go up.
What happens when this diver stops moving foreward?
They sink or they keep kicking or they pump air into the bc.
Good buoyancy control doesn't require the use of fins to maintain position. When a head up diver kicks they go up unless they are negative. I have never seen good control without good trim.
Prove it to yourself. Run a line course that has plenty of ups and downs and sharp turns. Divers who can follow and stay WITH the line including pivoting around the sharp turns are in control. Divers with poor trim won't get it done. Having the line there will make it obviouse. These divers if they are lucky or practiced at diving like this may stair step up or down the slope of the line but will not be able to follow the slope with the line. They also won't make the turns without changing depth because when they stop they will sink or rise.
The only way to swim foreward and be neutral is to be horizantal. If this can work another way I am willing to drive a long way to see it.
How good is the Dm? And how comfortable is the diver at 40 or 50 feet? If the DM is good and the diver is comfortable at shallower depths is see no problem with one on one guided tours to 80 or 90 feet. A good DM will recognize increased anxiety and stress and take the dive shallower if needed. One DM trying to do this with two or more divers can be a accident waiting to happen IMO.
With that said, IME, i would trust less than 50% of the DM's i've seen in the carribean with people i care about. Many seem to be less than attentive IMO.
OP
And with the addition of a thick suit and a bunch of poorly placed weight and maybe a free flowing reg they are nothing but meat.
That depends on what your definition of "is" is.
Seriously Mike, i think we a talking two different extremes here. You stance, perfect weighting, perfect trim, therefore very little depth change in movement or hover positions. My stance, not so perfect weighting, therefore not so perfect trim, slightly more depth changes in movement or hover positions with breathing control taking a larger part in controlling your buoyancy.
I'm not trying to say perfect trim or weighting aren't better. They are, no question. However i don't believe it's realistic or absolutely necessary to good buoyancy control. I'm living proof Mike. Before this board, i've had little exposure to the more technical trim techniques that were born out of the cave community. Better trim is great quest for all of us to be on and i am on that quest but almost 25 years of successful diving without it leads me to believe it isn't absolutely necessary to safe diving.
I would hate to see new divers never leave pool like environments because their trim isn't perfect and they believe diving isn't safe without perfect trim. IMO you do not have to be trimmed out perfectly to dive safe. You must however have good control of you buoyancy regardless of your trim. The tidal volume of your lungs plays a large part in that control.
OP
gedunk,
You have a valid point. Trim is not an ON or OFF thing. there is perfect on one end, lousy on the other and some stuff inbetween. As we move toward the lousy end we see more problems and even more injuries (reference the DAN report). Some where inbetween hopefully closer to perfect than lousy may be a point that we should call minimum proficience.
As far as trim goes the point I am always trying to push is that puting the weight in the right place gets you 80% or more of the way there. Put the weight in the wrong place and nobody can do it. Many instructors (especially in cold water) put their students in a position where they can do nothing but fail. To improve this all that is required is to move weight up off the waist. It is that simple.
In the tropics it's easy because you don't need a suit or much weight. Put these same divers in cold water and they fight the entire time. No wonder there are so many who only dive on vacation. I think it's more than the cold it's the equipment and resultant discomfort.
You have a valid point. Trim is not an ON or OFF thing. there is perfect on one end, lousy on the other and some stuff inbetween. As we move toward the lousy end we see more problems and even more injuries (reference the DAN report). Some where inbetween hopefully closer to perfect than lousy may be a point that we should call minimum proficience.
As far as trim goes the point I am always trying to push is that puting the weight in the right place gets you 80% or more of the way there. Put the weight in the wrong place and nobody can do it. Many instructors (especially in cold water) put their students in a position where they can do nothing but fail. To improve this all that is required is to move weight up off the waist. It is that simple.
In the tropics it's easy because you don't need a suit or much weight. Put these same divers in cold water and they fight the entire time. No wonder there are so many who only dive on vacation. I think it's more than the cold it's the equipment and resultant discomfort.
OP
My first rescue was a diver who was head up and negative. She stopped kicking to look for her gauges and dropped like a rock. I almost lost my ears going after her and by the time I cought her she was in all out panic mode. I had to drag her up 70 ft being clawed the whole way. She spit out her reg. She knocked my reg out. The instructor who had just certified her had ear trouble herself and was unable to descent to help.
Poor trim contributes to divers not being neutral. That leads to trouble because if they stop swimming to perform a task their depth changes. If their attention is diverted say because of a minor problem they have to deal with this also. This alone is more task load than many divers can handle. Combine it with the resultant siltout or buddy seperation and you have a formula for disaster. Two divers stop to initiate air sharing and one goes up while the other goe down. The one who goes down causes a silt out and...
Aside from the bc and trim issue the thing I notice when I watch rec divers is I rarely see a functioning buddy team. when there is a problem the usual answer is to bolt for the surface.
Poor trim contributes to divers not being neutral. That leads to trouble because if they stop swimming to perform a task their depth changes. If their attention is diverted say because of a minor problem they have to deal with this also. This alone is more task load than many divers can handle. Combine it with the resultant siltout or buddy seperation and you have a formula for disaster. Two divers stop to initiate air sharing and one goes up while the other goe down. The one who goes down causes a silt out and...
Aside from the bc and trim issue the thing I notice when I watch rec divers is I rarely see a functioning buddy team. when there is a problem the usual answer is to bolt for the surface.
Ari
Moderator
Is that a good DM is priceless.
He will take you to the best sites, at the right time to watch the sharks swiming by, he will know the currents and tides at each site, at the specific time of day, etc.
Other than being worth it for the better diving, the safety implications are great as well.
Ari
He will take you to the best sites, at the right time to watch the sharks swiming by, he will know the currents and tides at each site, at the specific time of day, etc.
Other than being worth it for the better diving, the safety implications are great as well.
Ari
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