tombiowami
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How do they go about getting your correct weighting in a DIR F class?
Tommy
Tommy
DIRF, A Sobering Experience
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detroit diver
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Tommy,
Not too much different than in the classes you've already taken, but with some critical changes.
500 psi in the tank. Bleed your wings (BC). Keep removing weight to the point of just sinking. For every pound you take off, that's the less bouyancy in your wings you need to counteract it. It makes a HUGE difference when holding a position or doing skills in the 20 ft and above level. It made all the difference for me. I took off at least 9 lbs of weight.
But the balance issue is just as important. Center of gravity. Without it, the weighting is irrelevent.
I was in the class with Mike and Bill this past weekend. I've been lurking at the posts because they explained the class more eloquently than I could have. It made me realize how absurd the c-card agencies are and the type of diver that they are producing. As Mike said, it's all for the money. This class cost me $275.00 + lodging for the weekend. It was the best cash I ever spent on diving. (actually, I took half of the class in March when I got sick, so it cost me $550!!).
Let me throw out a question for the audience:
Why, during a charter, are we told to get back into the boat with 500 psi in our tanks?
Not too much different than in the classes you've already taken, but with some critical changes.
500 psi in the tank. Bleed your wings (BC). Keep removing weight to the point of just sinking. For every pound you take off, that's the less bouyancy in your wings you need to counteract it. It makes a HUGE difference when holding a position or doing skills in the 20 ft and above level. It made all the difference for me. I took off at least 9 lbs of weight.
But the balance issue is just as important. Center of gravity. Without it, the weighting is irrelevent.
I was in the class with Mike and Bill this past weekend. I've been lurking at the posts because they explained the class more eloquently than I could have. It made me realize how absurd the c-card agencies are and the type of diver that they are producing. As Mike said, it's all for the money. This class cost me $275.00 + lodging for the weekend. It was the best cash I ever spent on diving. (actually, I took half of the class in March when I got sick, so it cost me $550!!).
Let me throw out a question for the audience:
Why, during a charter, are we told to get back into the boat with 500 psi in our tanks?
detroit diver
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One more thing. Although I understand Mike reasoning behind it. this issue really doesn't belong in the Tek section. This class should be the standard for ALL divers.
Excellent post Roak. Thanks, that's one of the best things about this board, getting helpful info. You're description exactly describes a problem I've had when diving. When I stop finning my legs sink and you are correct...it really is wasted energy. I'm going to mess with my tank positioning on my next dive to try and fix this.Originally posted by roakey
OK, this is right off the top of my head but Ill throw it out for discussion anyway. Us DIR zealotstalk about gliding with the rig. We usually point to the hydrodynamics of the rig as to the reason we can glide like we do. Not to downplay the rig, but I think a lot of it has to do with trim too. Having correct static trim allows you all the time in the world between kicks, unlike correct dynamic trim. I can kick, glide forward, look around, check on my buddy, come to a complete stop, check my gas, futz about and then simply kick again and Im off.
If you only have correct dynamic trim, when you slow down and stop your legs sink. Your next kick has to accomplish two things, its got to get your legs up again AND propel you forward. So a good portion of your kick and therefore your energy is wasted in just maintaining correct trim. Your only other option is to not stop kicking in order to keep your trim flat. Then you end up looking like my puppy out for a walk, zipping back and forth and expending huge amounts of energy and, as a side effect, consuming huge amounts of gas.
Thoughts?
Roak
large_diver
Contributor
Kind of curious about a couple of points....
I just bought my BP 2 months ago (FredT) and set the harness up myself.
Curious about what guidance they gave regarding the following:
- Harness tightness
- Chest D ring positioning
- Backplate positioning (high high/low on your body)
- Tank positioning
- Other general comments about gear config. that may have surprised you or that seemed to be an issue with lots of folks
Thanks!
-Chris
I just bought my BP 2 months ago (FredT) and set the harness up myself.
Curious about what guidance they gave regarding the following:
- Harness tightness
- Chest D ring positioning
- Backplate positioning (high high/low on your body)
- Tank positioning
- Other general comments about gear config. that may have surprised you or that seemed to be an issue with lots of folks
Thanks!
-Chris
Roakey,
Your explanation of the mechanics of buoyancy control is absolutely correct. Speaking for myself, I teach the PADI OW course and I lecture all of what you said and in more detail complete with diagrams and cave diving video. I'm not trying to promote cave diving but to see an example of good trim this is where you usually must look. I don't teach students to depend on what you call dynamic trim (I describe it to students sa flying in the water because you use the flow of water over control surfaces). BTW the NACD cave diving manual "The Art of Safe Cave Diving" has an excelent chapter on this. But then again I sell bp/wing almost exclusively. I also have training and experience way beyond recreational diving. Training standards are not perfect but they are not what prevents divers from learning this stuff. One big problem is the fact that many instructors can't dive therefore can't teach. I have no defense for this. PADI understands the mechanics of trim and buoyancy control (it's not complicated). It is equipment manufacturers who are running the show. A shop must sell alot of junk to keep the dealership that allows them to sell you an Apeks reg. Its all tied together. Combine that with the reason most learn to dive. Underwater tourism is not the same as diving. Underwater sight seeing is what most are interested in. Even after my detailed trim/finning technique/buoyancy control lecture and seeing it demonstrated in the water of the few who will consider purchasing equipment some will still complain about the lack of color selection in a wing. I'm telling you, you can lead a horse to water but you can't suck it up through his ...Oh well you get the idea. To put in perspective, what some of us see as a problem, the rest of the diving world does not.
Your explanation of the mechanics of buoyancy control is absolutely correct. Speaking for myself, I teach the PADI OW course and I lecture all of what you said and in more detail complete with diagrams and cave diving video. I'm not trying to promote cave diving but to see an example of good trim this is where you usually must look. I don't teach students to depend on what you call dynamic trim (I describe it to students sa flying in the water because you use the flow of water over control surfaces). BTW the NACD cave diving manual "The Art of Safe Cave Diving" has an excelent chapter on this. But then again I sell bp/wing almost exclusively. I also have training and experience way beyond recreational diving. Training standards are not perfect but they are not what prevents divers from learning this stuff. One big problem is the fact that many instructors can't dive therefore can't teach. I have no defense for this. PADI understands the mechanics of trim and buoyancy control (it's not complicated). It is equipment manufacturers who are running the show. A shop must sell alot of junk to keep the dealership that allows them to sell you an Apeks reg. Its all tied together. Combine that with the reason most learn to dive. Underwater tourism is not the same as diving. Underwater sight seeing is what most are interested in. Even after my detailed trim/finning technique/buoyancy control lecture and seeing it demonstrated in the water of the few who will consider purchasing equipment some will still complain about the lack of color selection in a wing. I'm telling you, you can lead a horse to water but you can't suck it up through his ...Oh well you get the idea. To put in perspective, what some of us see as a problem, the rest of the diving world does not.
detroit diver
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Hi Chris,
Well, the harness will be tighter than you think! Actually, the top of the backplate should be at about the 2nd vertebrae. By cinching up the harness, you can achieve this height.
D-rings- Take each arm and extend it outright horizontal to the ground. Then move it across your body until you touch your other arm. The D ring should be placed just about there.
Tank positioning depends on your balance in the water. For my doubles, I try to get the bands as high as high as I can.
If you've got boots on your SPG, take 'em off. They cut mine off!! Funny thing is, I didn't know the boot could be taken off....
The other stuff you'll learn in class. All important, but not as visible as the above.
Well, the harness will be tighter than you think! Actually, the top of the backplate should be at about the 2nd vertebrae. By cinching up the harness, you can achieve this height.
D-rings- Take each arm and extend it outright horizontal to the ground. Then move it across your body until you touch your other arm. The D ring should be placed just about there.
Tank positioning depends on your balance in the water. For my doubles, I try to get the bands as high as high as I can.
If you've got boots on your SPG, take 'em off. They cut mine off!! Funny thing is, I didn't know the boot could be taken off....
The other stuff you'll learn in class. All important, but not as visible as the above.
If you have an AL80 cylinder positioning it won't help very much, you need some significant amount of weight up near your shoulder blades to flatten you out. Steel cylinders help, SS backplates help, but in lieu of either, throw some weight in the form of a HEAVY ankle weight around your valve or grab another cam band and put a weight up near the shoulder of the cylinder.Originally posted by GP
I'm going to mess with my tank positioning on my next dive to try and fix this.
Dont be bashful, lets say you dive with 20 lbs, try putting 10-15 lbs up near the cylinder's shoulder and see how it works out. In a pool, by the way.
Try the penny exercise in the post I pointed folks to a couple notes back.Note that even with 15 lbs of unditchable weight and an AL80, if youre properly weighted and you need to drop your weight belt youll be a couple pounds negative worst case, something you can swim up. Most importantly your ascent will be controlled, not a missle.
Roak
detroit diver,
Why would you let some jamoke on a charter boat dictate your gas management. But the answer is that they are prabably trying to force you into some kind of a gas management plan with a reserve.
Why would you let some jamoke on a charter boat dictate your gas management. But the answer is that they are prabably trying to force you into some kind of a gas management plan with a reserve.
From your posts not only do I think you're one of the few OW instructors that "get it" but you also teach it.
Tell me, is it that difficult to turn out exceptional (compared to the existing average) students when you put them in the right gear?
[ok, it's a leading question
]Roak
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