Stages and Trim Issue Question

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Rick Inman

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I've been diving with one or two 40cf's with no problem. But yesterday I dived a 40cf and an 80cf (O2 & 50%) for the first time, and started doing a major face plant. It really sucked (reminded me of my first dive in doubles). I couldn't figure out why switching one of the 40s to an 80 would make such a drastic difference. I ended up clipping the nose bolt-snap of the 40 to my hip D ring and that solved the problem for that dive.

So my question is, why such a difference switching to the 80? Is there something I should do/adjust, or will this trim issue work itself out with more dives (like so many other things have)?
 
Wow, funny that you should mention this, since I was just wondering the same thing. I notice my trim moves forward when I start adding bottles. My theory is that the bottles are nose heavy and move weight to the shoulder d-ring, which drags the head down and raises the feet. If you try to back kick like this, you'll move up and backwards in a very uncomfortable way.

I was considering moving the d-dring lower to see if that would shift enough weight backwards, but I hope someone might have some insight.
 
I know what you mean...

If I'm diving with 50% and 100%. I had been taught to have the 100% just clipped on my waist D ring by the top stage clip only. The 50% is clipped to left chest and waist D rings. 100% hangs on my waist D ring by one clip only. I find this unclutters things and its not that bad switching them around when it's time to go from 50% to 100%. Also, it ensures that I don't go for the 100% at the 50% switch point even though we've been taught to look at the label and confirm with that with your buddy...
 
Luxfer
GDI:
Rick,Where are your 80's clips located?
Clips located as per instructions HERE.
 
It is like the first time with doubles, and will be again once you start adding more. you'll get used to it, use legs to counter balance (but you know that).

All my stages/deco bottles are clipped of on chest AND hip if on the side. If more, then leash it behind you.
 
I think it also depends on the wing you use. Adding another AL80 adds another 6# of negative buoyancy to deal with (assuming no helium) so you'll be carrying that much more gas in your wing when the bottle is full, concentrated mostly on the left side if that's where you carry the tank. If your wing is the type with a wide rear, then that's where the gas will go adding more lift towards your butt and causing potential trim issues. Of course, if the top of the bottle is clipped to the hip d-ring, then it should more or less offset the extra gas at the rear of the wing.
 
Rick Inman:
So my question is, why such a difference switching to the 80? Is there something I should do/adjust, or will this trim issue work itself out with more dives (like so many other things have)?
Yo Yo Yo,

Everyone who moves to this configuration initially goes through the same thing. Not to worry.

Remember in your Fundies course how you went over the body position thing with the feet, etc? (Per Meng Tze's post above...) It works.

Just give it some time. I was initially doing face plants too. Discouraging.

It's just a matter of getting used to the extra weight.

On the wing thing, I don't know about how much difference other wings might make. My buddies and myself all use Halcyon - but it's irrelevant. You can get used to it in any wing you may be diving. There are a couple tricks that make it easier. Spend some time at a platform in a training environment. If you roll right laterally a bit while holding onto something you can displace more air into the left side of your wing. Give it a try. (The 'holding on to something' bit allows you to precisely get a feel for how much gas is moving. You will hear the gas moving from the right to the left. Figure out how much you need. The platform is just a tool to check your trim before and after.) Work with it a bit and you'll feel the difference. Makes it easier to get used to the 80 clipped to your left shoulder D. (Don't clip it to your waist...) Another is if you're using an extra reel, don't hang it on your left waist D. Move it to your butt D. If you need it, it'll be available, and until then it will hang down and annoy you properly while you're frog kicking! (This is incentive to get a scooter, so you can forget about it! :wink: )

Eventually, like anything else, you dive it enough and you will roll, shrug, hump around, and stretch your legs out enough that things will fall into place and you'll be comfortable with it. It just takes some getting used to.

One thing, though, for me at least, is that this combo is about the max I can swim around with. And in current it's a PITA...not to mention potential CO2 build-up. Therefore if it's a dive requiring a 40/80, as far as I'm concerned it's a dive for a scooter as well, but that's just me.

Another thing is that I began using this in caves. Practicing taking the bottles off and laying them gently on the bottom, then swimming back to them and re-attaching them without raising any silt, was challenging for me to learn. (Not to mention this is where (not wearing gloves) the brass gates began to give me tiny cuts in my fingers....so I switched to SS.) It took quite awhile getting used to dropping the weight (exhaling to counteract sudden positive bouyancy) and then adding the weight (inhaling to counteract sudden negative bouyancy) to keep the trim dead on.

So don't sweat it. Like most other skills it's definitely disconcerting at first but you will get dialed in with the 40/80 combo after numerous dives. You just need to put the time in practicing to work out the issues.

(Then you get to work with lines and reels while wearing them, and then perform all your skills without a mask while wearing them! What a bonus! :D )

Doc
 
Doc Intrepid:
..
One thing, though, for me at least, is that this combo is about the max I can swim around with....

Whimp......:wink: But yes it does get heavy hauling 2 80's and a 40 plus backgas around against flow...
 
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