Trim in midwater

[JeffG]

Why is it I get the feeling that this trim issue must be worse than what we would like to believe?

Until we are there ourselves, we will never know.

Honestly Lynn, between you and Peter and all your worri-some questions and threads, I think my best advice would be to chilax a bit and just go diving for the sake of the fun of it, for a change.

paralysis by analysis

 

[JeffG]

There are requirements, standards, expectations etc. One of them is to stay in trim while doing something (drills, deco, whatever). If you comply with it you'll pass. The question was why it's a BIG deal to maintain perfect trim during midwater ascent. I'll throw another:

1. Less drag when moving horizontal and all consequences that come from this (less effort, lower CO2 build-up, lower SAC, etc.)
2. Better situational awarenes - when you're in trim you don't sleep
3. Better control
4. Easier to dump wing
5. Trim becoming second nature to be prepared for silty environment
6. Good trim makes keeping neutral bouyancy easier which is important when switching (identify, deploy, check depth, breath).

To me this reads like cyberdiving at its best.

#2...are you kidding me.

To dump your wing or your drysuit, the diver typically will be "out of trim" for a moment.

 

[Steve R]

paralysis by analysis

lol, yup.

I think this affliction has nailed us all at one time or another.

As with you Jeff, I think there are about a million other things I would worry about before I got down to contemplating the out of trim issue for a second or two during a dive, for what might be good reason.

Don't get me wrong, I hate like hell doing 'commercial work' and looking bad doing moorings and such, but I actually feel it's at times just way easier to get it done while standing on the bottom.....lol....so I get over myself and decide to just look horrible for a few minutes.

Besides, if I hump the pooch for no reason, my buddy will generally tell me afterwards.

Which rule was that again anyway?

 

[RTodd]

No "itch" to get out of trim. I just failed my Rec Triox reeval dive for failure to maintain flat trim during ascents. And although I am not arguing that standard aren't standards or that I should have passed, I'm just frustrated by being unable to explain the utility of perfect trim on ascent. The issue of drag while swimming doesn't come into it, as you are on deco and floating. You may perhaps have slightly better control, but again, I'm not talking about vertical here, just a little out of trim.

Anyway, from information I've gathered, it appears that this is a BIG deal, and I just want to wrap my brain around why. One of the thing I like most about DIR diving is that things have reasons, and I just don't understand this one.

Deco is more effecient when your lungs are horizontal and you can get to your buddy to render assistance more quickly.

 

[rjack321]

Lynne's trim has been fine for the bulk of her dives with me. Not necessarily perfect but 95% of the time <25deg of wheelie.

Get your instructor to justify the criteria and the fail mark, not the internet. That's what video review and critique are designed for.

In T1 AG told me he didn't give a damn about our midwater trim as long as we held our stops under all the duress. I think the heretic has it right.

 

[Peter Guy]

rtodd wrote

Deco is more effecient when your lungs are horizontal

Do you have ANY evidence to back up this statement? Your lungs are what, maybe 14 inches long -- how would offgassing be any different even if you were doing sommersaults as long as the midpoint stayed the same. The gradient differential between being totally vertical and totally horizontal has got to be inconsequential. What is it that you contend makes "deco more efficient?"

rt wrote

you can get to your buddy to render assistance more quickly

Again, what evidence for this statement? Is it really your contention that someone at 0 degrees off the plane has any better response time that someone, say 20 degrees off the plane?

Now granted I'm a "baby DIR" type (and truth to tell, not convinced of all of its holiness and wisdom), but statements like these just seem to be designed as justifications for something else.

 

[boomx5]

In T1 AG told me he didn't give a damn about our midwater trim as long as we held our stops under all the duress. I think the heretic has it right.

I tend to agree! This BS of, "your left knee was .0002 of an inch to low so therefore you need to work on your trim more", does nothing for real world diving. A diver can be held to any standard by an instructor, but that doesn't mean that instructor is right...or being realistic. Lynn, don't be so fixated on the minutia and look to the big picture. I remember seeing a video over at AG's house one time of him and Chris Le Maillot doing some skill work down in Mexico. While doing the skills, Chris's trim was off a bit but I don't think anyone is going to fail that guy or question his skills!

 

[TSandM]

Why is it I get the feeling that this trim issue must be worse than what we would like to believe?

According to my instructor, I was up to 30 degrees off horizontal at times.

Yeah, I know what's wrong, and I have plans in place to fix it.

I just wanted to know why it was so important. I'm glad people are offering thoughts, although I may not find many of them very convincing.

 

[MonkSeal]

To me this reads like cyberdiving at its best.

If somebody else had written this I would've taken it as offence. However, it was you

#2...are you kidding me.

That's my favorite one.

To dump your wing or your drysuit, the diver typically will be "out of trim" for a moment.

Not 30 degrees as Lynn mentioned.

 

[rjack321]

According to my instructor, I was up to 30 degrees off horizontal at times.

Everyone who dives a drysuit is off at least some of the time.

Yeah, I know what's wrong, and I have plans in place to fix it.

Phewww

I just wanted to know why it was so important. I'm glad people are offering thoughts, although I may not find many of them very convincing.

I believe the standards say something like, "overall diver control is an important evaluation parameter." I wouldn't withhold certification from someone at the DIRF/triox level for marginal (midwater at that) trim. Seems senselessly punative to me. Just pointing out its borderline nature and admonishing the student to rectify it before C1/T1 should be adequate.