SDI DMs and up must demonstrate skills while neutrally buoyant

[boulderjohn]

My understanding of the relation between proper weighting, buoyancy, and trim came a bit many years ago following this sequence.

1. I was first quite fanatical about getting my weighting about as perfect as I could get it. I was then diving a traditional setup in the ocean, and I learned that 8 pounds was perfect for me with a 3mm suit and an AL 80. My BCD did not have trim pockets, and I had never heard of the idea anyway.
2. I switched to a ScubaPro Nighthawk BCD, which had well-placed trim pockets near the shoulder. Dividing my 8 pounds into 4 groups of two was a revelation. I loved it.
3. I started technical dive training, using a backplate and wing and steel double tanks. I had no choice but to be significantly overweighted in that early training. I was also required to be in good trim and neutrally buoyant.
4. I still used the Nighthawk for recreational dives, and on a dive trip I discovered on the way to the dive site that the boat only had 4 pound weights. If I wanted to be perfectly weighted with 8 pounds, I could only carry the weights in 2 of the 4 pockets. After deliberating and considering my recent experience of being overweighted with steel doubles, I opted to take 16 pounds (double my correct weighting), but distributed properly for trim. I had a marvelous dive--perfectly in trim and nicely buoyant. After the first dive, people openly complimented me on the boat and asked for tips.

A few weeks ago I began two weeks of recreational diving in Roatan. Some of you may have seen my thread on my packing disaster--I left my Single Tank Adapter home, I could not use the BP/W I had brought, and I could not find a suitable replacement. I had to rent jacket BCDs for those two weeks of diving. Because of the enormous volume of the two different BCDs I rented (ScubaPro and Aqualung), I had to use much more weight than I normally would. Both BCDs had trim pockets. After experimentation, I found that distributing the weight evenly among the pockets gave me nice trim--even though I was a few pounds overweighted.

The moral of the story:

• It is easier to achieve neutral buoyancy during a dive if you are ideally weighted, but you can achieve neutral buoyancy even if reasonably overweighted.
• You can be properly weighted and be totally out of trim because of weight distribution. If achieving proper trim through weight distribution requires that you be a few pounds overweighted, go with the proper trim.

 

[boulderjohn]

I wanted to add this part separately from my post above.

Many of you will know that I was an early and public advocate of neutrally buoyant OW instruction. I experimented with it a little at a time on my own, then convened a group of like-minded instructors to discuss how to do it. We published an article on neutrally buoyant OW instruction the PADI Undersea Journal a decade ago. Soon after that, PADI began to promote NB instruction, although not nearly to the degree I wanted. They published new standards that included teaching trim in the OW classes--they included a video showing an instructor adjusting a student's weight distribution to achieve horizontal trim, and the video showed the student hovering in trim.

I was then teaching for a shop that required us to use jacket BCDs, and those BCDs did not have trim pockets. We added pockets to the cam bands. That created a problem. Teaching students neutrally buoyant is best if they are properly weighted and in trim. Teaching students that way in 3mm wetsuits in a freshwater pool often requires them to have less weight than you can properly distribute for trim. Once again, what became evident was that getting the trim distribution as optimal as possible, even if it made them a little overweighted, was the best choice.

 

[wetb4igetinthewater]

No, I don't generally read the SDI blog at all.

Well you'd have saved us all a lot of trouble if you had.

I'm not trying to be pedantic. I genuinely believe that telling students that weight, buoyancy, and trim are not separate is doing them a disservice. As I have already explained.

Who said they were separate? And please, my question earlier is no indicatation

Divers should be able to maintain their buoyancy even if they do happen to be over weighted. That skill will serve them well should they ever be fortunate enough to dive with a steel 100 or 120, instead of an AL80. I have dived with more than one person who was taught that weight, buoyancy, and trim are not separate - divers who dived with a steel 100 for the first time and found their buoyancy was totally screwed. And in their minds, they felt heavy so they concluded that their problem was too much lead. Even though they had actually adjusted and were correctly weighted for the new tank.

Had they been taught correctly, they would understand that they were correctly weighted and the problem with their buoyancy was not that they were over weighted - rather that their buoyancy control was not as good as they thought. That they are carrying more gas, so they are more negative at the start, which makes buoyancy harder. So, they need to focus on improving their buoyancy control, not start removing lead (which would leave them too light at the end if they happened to breathe their tank all the way down).

Divers should understand that trim is "whatever orientation your body is, in the water". Trim is not "being horizontal in the water". And "good trim" is whatever orientation makes your current task the easiest and most efficient. Good trim is NOT always being horizontal. And, as someone else already pointed out, you can demonstrate perfect buoyancy while hovering in the Buddha position. Your buoyancy is unrelated to your trim. They ARE separate.

When you tell new divers that weight, buoyancy and trim are not separate, you make it REALLY hard for them to diagnose and fix issues. "I keep tilting forward. Does that mean I need to change how much lead I'm carrying, or breathe differently, or what?" How do you expect them to diagnose and fix issues if you teach them that all those things are not separate? You're telling them that they might need to change any or all 3 of those things.

No one is saying this. AT ALL. We are saying how all of these things are related.

First step is determining correct amount of weight. Second step is determining weight distribution. I actually teach finning at the surface on the back (as I have written in my blog series). But third is finning through the water horizontally and hovering to check that there is no tilt.

I'm dissappointed we are having to correct your misunderstanding.

 

[NorCalDM]

No. Over weighted does NOT equal negatively buoyant. You can be 10# over weighted and still be positively buoyant. Period.

Ya you can be over weighted and positively buoyant and I said that in my next statement. You stated if you were over weighted it implied to you they didn't have enough lift in their BCD so which is it.

If you are correctly weighted, you will STILL be negative unless you use your BCD to compensate - unless your tank is also empty or nearly so.

My statement said nothing about being correctly weighted it was about over weighting and negatively buoyant. I was replying to finning to compensate for over weighted and or negatively buoyant and again I see it all time.

 

[wetb4igetinthewater]

And as we learned from Linnea Mills, you can be so overweighted that no amount of air in your BCD will make you positive. Or even neutral.

 

[tursiops]

My statement said nothing about being correctly weighted it was about over weighting and negatively buoyant. I was replying to finning to compensate for over weighted and or negatively buoyant and again I see it all time.

Yes, one needs to fin to compensate for negative buoyancy....or add gas to their BCD.
One does not need to fin to compensate for overweighting, unless negative buoyancy is the result of the over weighting.

This whole thread may indicate why students don't get the info and help they need; instructors and mentors may be using words and concepts imprecisely or even incorrectly.

 

[inquis]

If I wanted to be perfectly weighted with 8 pounds, I could only carry the weights in 2 of the 4 pockets

I don't wish to detract from your main point of prioritizing trim at the expense of being overweight. I did want to point out the distribution is fairly "separable" in the two axes of rotation, which would have allowed you to carry 4 lb in the left trim pocket and 4 lb on the right waist pocket.

In my case, I prefer 7 lb up top (upper cam band) and 5 on the waist to optimize trim. Of course, no one has 3.5 lb and 2.5 lb bricks. I often get funny looks when asking for 4, 3, 3, and 2 lbs bricks, but that set allows putting a total of 6 lb on both left and right as well as the 7/5 split top-to-bottom.

Back to your point, though, 2 lb bricks are less common when traveling, in which case I normally use 3 lb bricks all around and compensate with arm/leg positioning. Based on your post, I plan to use 4&4 up top and 3&3 on the waist next time the brick selection is limited. Slightly overweight but achieving the desired distribution top-to-bottom.

 

[Jim Lapenta]

I'm not having a go at you personally. I would love for all of us (instructors) to get on the same page with what and how we're teaching. But, that requires saying correct things to the students. I've been having issues here with the things you are saying that you say to students.



No. Over weighted does NOT equal negatively buoyant. You can be 10# over weighted and still be positively buoyant. Period.



If you are correctly weighted, you will STILL be negative unless you use your BCD to compensate - unless your tank is also empty or nearly so.



We get to the pool around 8am. Usually leave by about noon. Students are generally in the water for about 2 hours during that. They do 5 builds of their scuba unit at the shop, in the classroom, the afternoon before, so no pool time wasted for that. They do the swim test at the very beginning, before donning wetsuits.

Regardless, I don't find any of these "requirements" that you are asserting in the Standards. Am I missing something? Are they in another area of the SDI Instructor documentation?

https://www.tdisdi.com/wp-content/uploads/files/sandp/currentYear/SDI/part%202/pdf/individual/SDI%20Diver%20Standards_07_Open_Water_Scuba_Diver.pdf

I didn't believe it could be done, either, when I moved here and joined this shop. My prior experience was always 2 days (full mornings) of pool sessions. But, I showed up to help with my first pool session with an open mind. Seeing is believing.

Look at the confined water slates. In each session assembly/disassembly are checked off. The confined water sessions are 4 distinct sessions separated by these as well as a debrief at the end of each session and practice time at the end of each. I won't do less than 5 because of the swim tests and free swims/dive skills I teach. That's a 2 hour session there.
I have the slates in front of me and I go through and check off each item as we do them. And I want to see them do it a few times before I check it off in that session. Once is not enough.
Then you have all the skills to get through and I know I'm not satisfied with them doing it one or two times. I prefer they repeat the basics in each session and do weight checks to get into the habit of doing it. They are supposed to do 4 buddy checks. One at the beginning of each session.
Tired diver tow, 5 (minimum) mask clears including a no mask swim ( I expect them to mask clear a dozen times before open water so it's instinctual).
I can't imagine how fast it has to happen to get through what I am seeing as 45 separate items (not including the assembly/disassembly) at least on the slates that should be checked off. Not only can't I do it based on what I see needs to be completed, but I could see my students eyes glazing over trying to get through all that and retain it.
I have had to take an entire pool session with one student who had numerous issues that we needed patience to overcome. I now refuse to take more than 2 people at a time if they live in the same house and otherwise it's one on one only.
And coming up on 62 years old, I'm not rushing anyone through anything. Including myself.

 

[stuartv]

Look at the confined water slates.

The slates are not agency Standards, nor even mentioned in the Standards. I do refer to them to make sure I don't forget to cover any required skills. Using them as an exact template for how the class is supposed to be taught is, well, not what I or anyone at my shop does. That is one of the things I really like about teaching under SDI. SDI instructors have a LOT of flexibility in HOW to teach the class. There is no REQUIREMENT for 4 entry and exits in confined water, for example, even though exactly following the slates would have that as one of the results. When were your slates printed, by the way?

As I have said several times. I came into my current shop assuming that all our OW students would have 2 days of pool time. I was shocked when I learned that's not how they (now we) do it. I was highly skeptical that decent divers could be trained with only one pool session. But, I kept an open mind and watched and learned. Now, after working for the shop since the end of April and participating in classes for, I don't know, 50 OW students(?), I can see that the results speak for themselves. To be clear, I feel like Amanda Baker is the Master of preparing students well for OW checkouts in just one pool session. I am still learning from her every time we teach. John has been out of the water since I've been at the shop, so I have yet to see him in action with OW students. And probably won't any time soon, as he generally teaches tech and Amanda generally handles the OW training (with help from myself and others).

We do not add Rescue skills to the OW class. We do not add freediving skills. So, we would certainly be able to accomplish all the CW stuff in less time than what you need. That said, I personally am skeptical of adding that much to the OW class. Not without also adding a number of dives beyond the required 4 OW dives. They have more than enough to digest without adding all those additional skills. But, that is just my opinion and, like when I came to my current shop, I am open-minded about other ways of doing things - especially if they come with a track record of good results.

 

[stuartv]

Ya you can be over weighted and positively buoyant and I said that in my next statement. You stated if you were over weighted it implied to you they didn't have enough lift in their BCD so which is it.

No, I said:

I have never seen someone finning from being over weighted. That would imply to me that they don't have enough lift available from their BCD. I have definitely never had a student that was so heavily weighted that their BCD did not have enough lift to keep them off the bottom and thus forcing them to fin just to hold their depth.

What I HAVE seen (LOTS) is divers who fin constantly because they are negatively buoyant. But, no matter what their trim or weighting is (unless they are too heavy for the lift of their BCD), they can stop that finning by adding some air to their BCD and getting neutral. Even if they are over weighted.

If they HAVE to fin, that means their BCD doesn't have enough lift. If their BCD does have enough lift, then they don't HAVE to fin. They just need to add more air to their BCD.

My statement said nothing about being correctly weighted it was about over weighting and negatively buoyant. I was replying to finning to compensate for over weighted and or negatively buoyant and again I see it all time.

You said:

Over weighted = negatively buoyant.

In saying that you are negatively buoyant when you are correctly weighted, I demonstrated that your statement is false. Over weighted IS NOT EQUAL TO being negatively buoyant.

You do not see people finning because they are over weighted (unless they are SO over weighted that they exceed their BCD's lift - which was the point I was making that you originally responded to). You see people finning because they are negatively buoyant. And that happens to divers who are over weighted AND to ones that are weighted correctly. (Assuming not over weighted to the point of exceeding their BCD's lift) being over weighted has NOTHING to do with them finning to maintain their depth. Being negatively buoyant does - which can happen no matter what your weighting is. And THAT is my point - to decouple the concepts of weighting and buoyancy control. Saying "you're constantly finning and that's because you're over weight" is just plain WRONG. They're finning because they have not established neutral buoyancy - which they can do whether they are correctly weighted or over weighted.