Neutral at surface or 10 feet?

[headhunter]

I'm waiting for the DIR Fundamentals book to arrive in the mail and the answer may be in there, but I thought I'd ask. I tried to search the board for specific answers with reasons to my questions and couldn't find them.

I've done searches on bouyancy and seem to come up with 2 schools of thought on how to adjust one's weighting.

I was taught to adjust my weight so that motionless with no air in my BC I should float eye level at surface. I've seen advice to that end on the board.

There seems to be another school of thought that your weight should be adjusted so that motionless with no air in your BC you should be neutral at 10 ft. (your final deco/safety stop). It seems that in a wetsuit this would make it increasingly difficult to hold your 10 ft. stop if you were to drift up a couple of feet (because of a more bouyant suit). It also seems that at surface you would have to swim your suit down for the first 10 ft. because you are too positive.

Are these two different schools of thought or did I miss something in my thought process?

What is the DIR perspective and why?

Does the answer change if you are diving wet or dry?

Thanks.

Christian

 

[bcsean]

Well in my DIR-F course this past weekend we did weight checks. at the end of a dive, we bled our tanks down to 500psi, laid on the bottom, roughly 20', dumped all air out of drysuit and wing, and laid flat. when you exhale, if you still drop, you're fine, if you start to go to the surface, you're underweighted.

Essentially you need to be able to hit your stops and maintain a controlled ascent. These drills are just designed to get your close. It's up to you to fine tune from there.

 

[MHK]

I'm waiting for the DIR Fundamentals book to arrive in the mail and the answer may be in there, but I thought I'd ask. I tried to search the board for specific answers with reasons to my questions and couldn't find them.

I've done searches on bouyancy and seem to come up with 2 schools of thought on how to adjust one's weighting.

I was taught to adjust my weight so that motionless with no air in my BC I should float eye level at surface. I've seen advice to that end on the board.

There seems to be another school of thought that your weight should be adjusted so that motionless with no air in your BC you should be neutral at 10 ft. (your final deco/safety stop). It seems that in a wetsuit this would make it increasingly difficult to hold your 10 ft. stop if you were to drift up a couple of feet (because of a more bouyant suit). It also seems that at surface you would have to swim your suit down for the first 10 ft. because you are too positive.

Are these two different schools of thought or did I miss something in my thought process?

What is the DIR perspective and why?

Does the answer change if you are diving wet or dry?

Thanks.

Christian

Christian,

The answer(s) that you cite are essentially the same. Meaning that using the floating at eye level at the surface is a way to "guesstimate" what your weighting should be.

The more complete answer is you want to weight yourself so that when you have approximately 500 psi in your tank, you can hold your stop at 10'. There are several ways to test how much weight is needed. One is the best way, in my view, which is to actually be at 10' with 500 psi in your tank. You let all the air out of your wings, drysuit and hold as little air in your lungs as possible and then test how much.

The other way to :guess" is to use the eye floating test that you describe above. Again the idea is that such a method is just a different manner to test what the weight you want is..

Hope that helps..

Michael Kane

 

[Mo2vation]

Christian,

The answer(s) that you cite are essentially the same. Meaning that using the floating at eye level at the surface is a way to "guesstimate" what your weighting should be.

The more complete answer is you want to weight yourself so that when you have approximately 500 psi in your tank, you can hold your stop at 10'. There are several ways to test how much weight is needed. One is the best way, in my view, which is to actually be at 10' with 500 psi in your tank. You let all the air out of your wings, drysuit and hold as little air in your lungs as possible and then test how much.

The other way to :guess" is to use the eye floating test that you describe above. Again the idea is that such a method is just a different manner to test what the weight you want is..

Hope that helps..

Michael Kane

I went into DIR/F with my BP/W and 16 on the belt. The eyeball test put me at about 16.

By the end of the weekend, I was at 10 on the belt - and able to hold at 10'. Flailing at the stop, at the end of a dive when your tired is not fun. You gotta be able to hold at 10' while on empty. Its not smart to over weight yourself into a 10' hold and compensate with gas in the wing, etc. Its better to simply get the weighting dialed in.

I've since moved to 8, except when shooting, then I put on 10 (its easier to shoot a little heavier.)

The only way to really "know" is to get to 10', jacuzzi out all your gas from the can, empty your suit and wing and see what's doing.

K

 

[headhunter]

Christian,

The answer(s) that you cite are essentially the same. Meaning that using the floating at eye level at the surface is a way to "guesstimate" what your weighting should be.

The more complete answer is you want to weight yourself so that when you have approximately 500 psi in your tank, you can hold your stop at 10'. There are several ways to test how much weight is needed. One is the best way, in my view, which is to actually be at 10' with 500 psi in your tank. You let all the air out of your wings, drysuit and hold as little air in your lungs as possible and then test how much.

The other way to :guess" is to use the eye floating test that you describe above. Again the idea is that such a method is just a different manner to test what the weight you want is..

Hope that helps..

Michael Kane

Thanks Michael,

That is helpful. I think I understand now that the "eye level" method is intended to get you into the ballpark and that then you must "refine" your amount of weight for the 10' stop.

The only thing that I seem to be missing is this. If I'm wearing a wetsuit, neutral at 10' with only 500 psi in my tank and easily holding my stop there with simple breath control, wouldn't that make me too bouyant at anything above 10'?

I may be mistaken, but I am under the impression that most of the compression of my wetsuit is taking place somewhere in the first 10' or 15'. This makes me think that at 5' I'd be fighting to get down to 10'. Am I making a mistake here? Am I not thinking this all the way through?

By the way, I'm not questioning your methods here. I'm confident that if I do exactly what you're saying that I will achieve optimal results. In fact, that is what I'm going to do. Now that I've got the correct DIR answer about "how", I'm simply trying to understand "why" from an academic standpoint.

Thank you for your help.

Christian

 

[MHK]

Thanks Michael,

The only thing that I seem to be missing is this. If I'm wearing a wetsuit, neutral at 10' with only 500 psi in my tank and easily holding my stop there with simple breath control, wouldn't that make me too bouyant at anything above 10'?

I may be mistaken, but I am under the impression that most of the compression of my wetsuit is taking place somewhere in the first 10' or 15'. This makes me think that at 5' I'd be fighting to get down to 10'. Am I making a mistake here? Am I not thinking this all the way through?

By the way, I'm not questioning your methods here. I'm confident that if I do exactly what you're saying that I will achieve optimal results. In fact, that is what I'm going to do. Now that I've got the correct DIR answer about "how", I'm simply trying to understand "why" from an academic standpoint.

Thank you for your help.

Christian

You are doing the correct thing in terms of asking "WHY". I tell my students all the time the "why's" are much more important then the "how's"..

You correctly note that a wetsuit has buoynacy charahcteritics associated with it, especially in the 5' - 10' range. That is why we recommend shell drysuits to eliminate the guessing.

But that being said, when you start you're dive, ie; when "you are fighting to get down" you are also at the heaviest point in your dive. Your tanks are full so that will easily make up for the fact that after your dive is done, ie; your tanks are depleted and you are at your lightest point, that you'll have adequate weight to hold your 10' stop. Also, by descending in proper horizontal position you can easily kick down against any potential bouyancy issues associated with a w wetsuit.

Let me know if that helps or I'll be happy to follow up.

Michael Kane

 

[RIDIVER501]

Proper weighting.
Remember that if you are diving an aluminum 80 an empty tank is 6lbs positive. So if you are properly weighted when your tanks is full your are going to be slightly positive by the end of the dive becuase of the air you burned during the dive.

When I teach Peak Performance Bouyancy class I have weighted student one of two ways with success.
1 is to get into that empty bcd on the surface at eye level with a full tank holding a normal breath then add 6lbs of lead to be neutral at the end of the dive.

2 is to use a tank with 500psi and follow the same guidelines except you don;t have to add the 6 extra lbs....
both ways work equally as well in my experience.

technique varies for steel tanks...

 

[MXGratefulDiver]

I tell my students all the time the "why's" are much more important then the "how's"..

Agreed ... it's one of the things I appreciated most about the DIR-F class ... the focus on "why".

... Bob (Grateful Diver)

 

[PatH]

Proper weighting.
1 is to get into that empty bcd on the surface at eye level with a full tank holding a normal breath then add 6lbs of lead to be neutral at the end of the dive.

2 is to use a tank with 500psi and follow the same guidelines except you don;t have to add the 6 extra lbs....
both ways work equally as well in my experience.

technique varies for steel tanks...

I would suggest that this is overweighting your divers by about... 6 lbs. You want to be neutral (with empty BC) with 500 psi at the end of your dive at your last stop (10'?). If you are measuring for neutrality at the surface at the end of the dive you are overweighting.

Using the first method you don't need to add the 6 lbs to achieve this goal. With a standard recreational single 80 cf tank you should have to breath out almost completely in order to sink. If you are sinking without breath control you are overweight. Likely the principal reason why divers can strip off weight as they gain experience is because they gain breath control. If all works out properly you should arrive at your final stop neutral with nearly empty tanks and no air in your BC. The latter being the goal, the former the guesstimate.

 

[headhunter]

You are doing the correct thing in terms of asking "WHY". I tell my students all the time the "why's" are much more important then the "how's"..

You correctly note that a wetsuit has buoynacy charahcteritics associated with it, especially in the 5' - 10' range. That is why we recommend shell drysuits to eliminate the guessing.

But that being said, when you start you're dive, ie; when "you are fighting to get down" you are also at the heaviest point in your dive. Your tanks are full so that will easily make up for the fact that after your dive is done, ie; your tanks are depleted and you are at your lightest point, that you'll have adequate weight to hold your 10' stop. Also, by descending in proper horizontal position you can easily kick down against any potential bouyancy issues associated with a w wetsuit.

Let me know if that helps or I'll be happy to follow up.

Michael Kane

Yes that helps. I had a little light bulb go on when I was reading your last post!

So let me see if I understand now. I'm going to think out loud to see if I understand all of the issues involved.

At the beginning of my dive I'm anywhere from 4 - 8 lbs heavier than at the end, depending on the cylinder(s) I'm using. So, that's extra weight to help start the dive. At depth, I'll be heavy throughout the dive anyway and will simply compensate with the wing, so that's not an issue. At the end of the dive, I'll be properly weighted for my deco/safety stop at 10'. Proper horizontal positioning allows a quick kick that will help if I rise a bit. This kicking should only be used if necessary, but if I use proper weighting and bouyancy control technique in the first place, this would be the best way to avoid needing to kick at all. The ascent to the surface after the 10' stop is almost a moot point because even though I may be a bit bouyant as I ascend from the 10' stop, 10' is probably not enough distance to turn me into a Polaris missle. This method of establishing how much weight I need should yield the least amount of weight I can get away with. In addition to that, if I were to have a wing failure at depth while wearing a wetsuit, I would have the easiest time swimming up my rig, since I'm using the least amount of weight possible.

Let me know if it appears that I have a proper understanding of all the issues involved and please correct me if I got any of it wrong.

I've always said if I know "why" I can always figure out "how", since it usually follows naturally. Thanks for the help in understanding the "why"!

I got an email from GUE yesterday letting me know that my Fundamentals book has shipped via USPS. I look forward to reading it.

Michael, I don't want to impose, but I hope you will allow me to ask you one more question. Does the new DIR video series include a more in depth view of the DIR philosophy as an extension of the book or is it intended to accomplish a completely different purpose than the book?

To be clear, I'm not asking the question with it in mind that it would replace any classes. I don't believe that anything can replace physically doing something with guidance from a well trained instructor. What I am hoping to do is get the most thorough understanding of the entire system as possible before taking the class, so that I can devote more time to learning the practical application of the principles in class rather than learning all of the principles for the first time.

Thank you for your help. I really appreciate the time that you've taken to help me understand.

Christian