Tropical diving: correct amount of weight versus trim (correct weight distribution)

[lexvil]

If ya'll wanna believe it's the bad gear and a pound in the wrong place that's causing you trim or whatever else issues, so be it. I tried.

Do you dive your own gear?

 

[scubadada]

Long thread in Basic Scuba. The easiest thing to do would be to get divers to simply do a weight check at the end of the dive at their safety stop and use that to adjust their weighting. Near proper weighting would go a long way to eliminating many problems discussed in this thread and would make it easier to adjust residual trim problems. Many traditional BCs have "trim" pockets that would be a logical next step. This simple advice applies to rental gear as well as to one's own gear.

If "vacation" and other divers who do not dive frequently would just do this, it would go a long way toward improving their buoyancy and trim.

More advanced and experienced divers can do all sorts of things to fine tune their trim

 

[berndo]

Do you dive your own gear?

I've used rental gear from the shops I worked at plenty of times. Doesn't matter. It's not that anyone dives custom fitted fins or custom fitted BCs.

 

[lexvil]

I've used rental gear from the shops I worked at plenty of times. Doesn't matter. It's not that anyone dives custom fitted fins or custom fitted BCs.

So you do dive you own gear and infrequently use “other gear” but can’t tell the difference? Why own your gear?

I actually custom fit my gear to me as I’m not an “average” size

 

[-JD-]

When I'm driftng along a reef for an hour without moving or hardly moving. I also have my head up and feet low because it's more comfortable. People just repeating 'it's physics' over and over again is really saying nothing.
The OPs point about not being able to dive properly and in trim because of bad gear is just objectively not true. That's not semantics. We even had someone post video of someone explaining it and doing a demo.

If ya'll wanna believe it's the bad gear and a pound in the wrong place that's causing you trim or whatever else issues, so be it. I tried.

@berndo not just at you, but your posts are convenient ...

There certainly is a valid point that an unbalanced/imperfect physical (total-kit & body morphology) configuration can be compensated for by technique - to a point. Those techniques are important skills to build as perfect force balance is fleeting at best.

However, as the force balance moves further from perfect, the amount of compensation increases the cost of attention and discomfort, degrading performance and the experience (enjoyment).

Optimizing the base physical system configuration costs in advance, but reduces in-dive effort.

Much the same arguments apply to weighting. You CAN dive grossly overweighted -the uber-diver should be able to dive with a ships anchor hooked to them, it is all just a skills issue, right? But the more overweighted you are, the bigger the PITA it is.

Somewhere there is a balance between the SKILLs of putting your kit together "right" and compensating for the suboptimal reality by Technique.

The engineering mind tends toward the former ...

 

[FishWatcher747]

More advanced and experienced divers can do all sorts of things to fine tune their trim

Very good point that being overweighted is a big problem for overall trim. Less experienced divers should work on reducing weight as they progress and become less anxious about diving.

But why can't we at least mention proper weight distribution in OW courses? At least for PADI I don't recall any teaching on this topic.

I think the obvious answer is they would have to admit the rental gear we are providing you for the OW or AOW course does not allow the center of mass and the center of buoyancy to match up.

Sorry, we have provided you with gear that you will be foot heavy in, and we are not going to do a thing about it.

 

[berndo]

So you do dive you own gear and infrequently use “other gear” but can’t tell the difference? Why own your gear?

I don't know what you're trying to get at. I have an SP jacket from the 90s. I also have and used different wings and newer rental jackets. I don't see what the issue is.

I just tried to explain why I disagree with the OP. I think I speak from experience and gave examples. I get that ya'll don't care to hear it and I don't know what else to say.

 

[wetb4igetinthewater]

I’m a novice recreational diver trying to learn all I can. Can someone explain trim and it’s importance in diving, beside the air consumption? I tend to remain relatively prone in motion and just a hair bottom heavy when not. Feet dip somewhat when stationary. Is this an issue to be concerned about? Only weights I’ve used thus far have been a basic weight belt.

You might be interested in the 3-part blog series I wrote for SDI on how I teach neutral buoyancy and trim. Those can be found here:
Teaching Neutrally Buoyant and Trimmed - International Training - SDI | TDI | ERDI | PFI
Teaching Neutrally Buoyant and Trimmed: Pt2 - Mask, Snorkel & Fin Skills - International Training - SDI | TDI | ERDI | PFI
Teaching Neutrally Buoyant and Trimmed: How to weight properly, Part 3 - International Training - SDI | TDI | ERDI | PFI

So why is trim important? Well, if you are neutrally buoyant, any finning you do will send you in the direction your body is pointing. So if you are not trim and your head is higher than your feet, you'll slowly head to the surface which is probably not what you want. If you are horizontal, assuming a flat bottom, you are maintaining your distance from the bottom, which is of course probably what you want.

Very often people dive slightly negatively buoyant. They are easy to spot as they never stop finning or they sink. But they maintain their depth as the downward force of their finning offsets how negative they are. They move around finning more than what they should, expending energy and burning through their gas. Your finning should be smooth and only done when you want to move in some direction. Often you want to pause to look at something, possibly take a picture or video of say two octopuses battling it out over a coconut shell.

I remember when I first started diving I was doing a night dive off Isla Mujeres. There was this diver from Vancouver Island with over 1000 dives. He was perfectly flat, barely moving, occasional modified frog kicks where he'd glide through the water with hardly any effort. And he came back up with over half a tank while the rest of us, including myself, had burned through almost all of our gas.

I started this thread as this is how I normally dive. I was in a configuration where I was not able to do that. Some of my finning energy was wasted to get myself horizontal again and then propel myself forward. Maybe I'm a little overly obsessed with trim, but let me be me.

Please let me know if this doesn't answer your question or if you have more questions.

 

[divingdayz]

Simply the amount of poor buoyancy control and situational awareness I saw so much coral being broken. The worst diver was a photographer who had been diving since the 90s. He was crawling over the reef to take pics.

Unfortunatly, this is a common sight. Big camera, no buoyancy......................

 

[Bob DBF]

You CAN dive grossly overweighted -the uber-diver should be able to dive with a ships anchor hooked to them, it is all just a skills issue, right?

Which is why I usually have a pile of boat anchors in the shed. If held properly, one can maintain their trim, as well. I do not advise anyone to try this trick, as it is quite dangerous.