Rear trim weights, what do they do?

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1011ster

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Location
Athens,Greece
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50 - 99
Dear friends,
even though this is not necessarily a Mares only question,I like posting here, so your thoughts are needed. Did my first dive with my new Dragon AT the other day, and it did feel a bit akward. I have been diving el cheapo rentals with no integrated weights, and normally 8 kilos on my belt was just right for my summer attire. Dove the other day with my new toy, as well as wearing for the first time my new isotherm. Fist thing I noticed is that I couldn't go down with the added 2 kilos I thought I needed extra, so 2 more kilos were added for a total of 14. They were distributed 5 in each pocket and 4 on the belt. That kept me down, but I felt I had a very "torso heavy" position, like my legs were always higher than my body. Take into account my limited underwater experience, barely over 25 dives. Maybe it's all in my head, but I have heard about the rear trim weights , I just can't figure out whether I need them or for that matter how they work. Can one of you gurus out there help me out? Do you spread your weights between BC and belt? They told me to do so for safety reasons, in case I lose a pocket underwater, which makes sense to me.
Waiting for your input
Best regards
1011ster
 
Rather that "rear pockets", consider them to be "up high on the torso" pockets.

When you are horizontal, those trim pockets are closer to your head than are either a weightbelt or the main integrated pockets. When you look at it in that light, it is obvious that shifting more weight to the trim pockets will tend to make you go head down (or to eliminate the problem of going foot down).

Although you may have felt that your legs were always higher than your body, at least initially most people feel that way when they are truly horizontal. Get your buddy to take a look at how you are oriented in the water. Particularly important is what happens to your positioning or trim when you stop all movement -- no finning, no hand movement.
 
Trim weights let you move some weight up higher on your body. If you find that you have heavy legs then moving some weight from your belt up to rear trim pockets will tip your virtual see saw.

The pockets are in back just because that's where you can put them on the BC. A guy may get away with front trim pockets (nonexistent )but strapping lead to the chest of woman just isn't going to happen. It does raise your center of gravity a tad but not enough to matter. For cold water diving moving 6 pounds from my belt to trim pockets makes a huge difference.

Other tricks are clip-on weights on shoulder D rings, strapping weight to your tank with an extra cam band and throwing and ankle weight or 2 around the neck of your tank. I even dove with one guy that had 2 ankle weights strung together and worn as a necklace. Don't forget that how high you mount the cylinder will also mess with your balance, be sure to keep track of that.

You are taking the first important steps of analyzing how things are working. It may take a while to tweak it in but you will get there. When you do you will know it. :)

I generally do not use the ditchable pockets on my BC since I prefer to stay as close as possible to neutral when out of my BC.

Pete
 
I use the rear weight pockets in my Ranger to help me trim our horizontaly in the water.

They seem to help when I'm on the surface as well. I tend to want to go face down when floating on the surface with the BC inflated and no trim weight in the rear pockets.

Have not had many dives to perfect my weight and trim so I'm still working on it.
 
Thanks everyone for your info. I'll give those rear weight pockets a shot, see how that goes! Long way to go to get that damn buoyancy straight!
Thanks again!
1011ster
 
101, you got some great advice here! I would also like to add to what jethead said in that the trim pockets also help when at the surface! It balances the weight around your torso instead of having it all at the front helping stay vertical!

Here is my personal setup, hoping it will help, since I also dive in very cold water. I have a Morphos pro (2 MRS pockets in front, 2 trim pockets in rear), with a Bare artctic 7mm wetsuit and 7mm vest (that makes 14mm of neoprene:shakehead::shakehead:).

I use a total of 28 lbs when diving freshwater and using an AL80 tank. I usually distribute it 1/3 in the trim pockets, and 2/3 in the mrs pockets (evenly distributed of course). SO far, it has worked great for me and it might be a starting point for you to try!

Personally, I don't use a weight belt, although I do see why some might suggest you do. But I do check my weight pockets religiously before every single dive to make sure the locking mechanisms are well closed and holding the pockets in place.

Trial and error will eventually get you tuned in. May I suggest a pool session of intensive weight testing? This is what I did. I know that 1 hour in a pool with your complete setup, testing different weight setups, isn't the greatest of fun. But even if it's hot, I'm sure you will be able to get close to the right setup within that time and your next real dive will be so much more enjoyable. And you'll be able to fine tune the little differences afterwards as you do your regular dives (no more pool sessions).

Just my 0.02$
 
https://www.shearwater.com/products/perdix-ai/

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