OP
Yeah I noticed on my first twinset dive, and I tightened it after. What about should straps, do they matter?
Backmount Double Stability Issues
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MichaelMc
Working toward Cenotes
Yeah putting the weight in the plate does not help much, as it is all still behind you. Weight pockets on the side or side front of the harness hip belt. Possibly a little weight on the front shoulder straps, one to two pounds on each goes unnoticed. A light weight belt, with weights on the front not the back.
ETA: The plate is better than the center of the tanks by a few inches, but that might not be enough.
ETA: The plate is better than the center of the tanks by a few inches, but that might not be enough.
OP
Thanks! I'll try this tomorrow. Do you think stages might help a little bit since they are kind of 'hanging below me'?
MichaelMc
Working toward Cenotes
The physics of stages or sidemount tank anchor points still eludes me.
From sidemount, for me, LP50s are more stable that AL40s. I believe as the 40s extra lead just adds to the lead on my back as I've already used up the convenient lead spots on my front. Stages are often AL80. So if you have to add lead that lead just goes on the back, typically I think you have a mostly neutral thing hanging from your chest, and extra lead on your back. So that seems worse. If they are negative stages hanging below you like an anchor, that would help, but that seems rarer.
On stages, you can mount them like sidemount tanks by adding a bungee off the top side of the plate, if you do not need to manage many of them.
Jack Hammer
Contributor
OP
Yeah you're right. I only use AL80/40 as stages. These would probably only made things worse. Maybe I have to get used to it but it's so uncomfortable that I don't have the freedom to move around
OP
May I ask what tanks do you use?
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@QAQTAT
kind of going backwards through the thread, so forgive me for that.
Stages are roughly neutral when full and positive when empty. When full, they will cause you to want to list to the left a bit because they are negative and hanging, and when empty they will cause you to list to the right a bit because they're pulling your left side up. This is typically not enough to be really noticeable when you are experienced with doubles. Unless I am focusing just on the stages, I don't notice and my body will automatically compensate by adjusting one of my legs just enough to balance back out and if it is particularly egregious, you can pack air into one of the sides of the wing and fix the roll that way. We are talking 1-2lbs positive or negative per stage, so it's functionally irrelevant.
Doubles will ALWAYS be unstable when you are rolled all the way over on your side and there is nothing you can do to really fix it. The scuba rig is negatively buoyant, the lift is in the middle, and your body is positively buoyant. You will roll over. Over time you can learn to manage it with some creative leg positioning and various muscles in your core. Yes, you can roll and pitch over just by flexing certain muscles in your body even though didn't "move" any of your limbs. Certain tanks will make you want to roll harder than others, but they all will, so best to learn how to deal with it which will only come with time and practice.
In terms of the harness. Should straps loose! They need to be loose for safety and comfort. A consequence of that is that when you roll you will feel the whole rig move. When you are in trim, your body is floating up against the backplate and you are pinned to it. Your waist strap is doing all of the work to keep you and the rig attached. When you go head down, you float up and the crotch strap engages to keep you in place. When you go head up, the shoulder straps engage to keep you from floating away. If you are regularly spending time on your side, a harness like the Transplate will let you use a chest strap and can be fit fairly snug to help prevent that movement, but you should not tighten a one-piece harness to the point that the shoulders are snug. You should always be able to easily get a fist under the straps.
Any lead added to your body instead of the rig will work to help lower your center of mass and center of buoyancy which will help to improve stability.
kind of going backwards through the thread, so forgive me for that.
Stages are roughly neutral when full and positive when empty. When full, they will cause you to want to list to the left a bit because they are negative and hanging, and when empty they will cause you to list to the right a bit because they're pulling your left side up. This is typically not enough to be really noticeable when you are experienced with doubles. Unless I am focusing just on the stages, I don't notice and my body will automatically compensate by adjusting one of my legs just enough to balance back out and if it is particularly egregious, you can pack air into one of the sides of the wing and fix the roll that way. We are talking 1-2lbs positive or negative per stage, so it's functionally irrelevant.
Doubles will ALWAYS be unstable when you are rolled all the way over on your side and there is nothing you can do to really fix it. The scuba rig is negatively buoyant, the lift is in the middle, and your body is positively buoyant. You will roll over. Over time you can learn to manage it with some creative leg positioning and various muscles in your core. Yes, you can roll and pitch over just by flexing certain muscles in your body even though didn't "move" any of your limbs. Certain tanks will make you want to roll harder than others, but they all will, so best to learn how to deal with it which will only come with time and practice.
In terms of the harness. Should straps loose! They need to be loose for safety and comfort. A consequence of that is that when you roll you will feel the whole rig move. When you are in trim, your body is floating up against the backplate and you are pinned to it. Your waist strap is doing all of the work to keep you and the rig attached. When you go head down, you float up and the crotch strap engages to keep you in place. When you go head up, the shoulder straps engage to keep you from floating away. If you are regularly spending time on your side, a harness like the Transplate will let you use a chest strap and can be fit fairly snug to help prevent that movement, but you should not tighten a one-piece harness to the point that the shoulders are snug. You should always be able to easily get a fist under the straps.
Any lead added to your body instead of the rig will work to help lower your center of mass and center of buoyancy which will help to improve stability.
MichaelMc
Working toward Cenotes
With the LP50s or LP85s do an extreme move of all your lead as far forward as you can. That may not be practical but it will tell you the envelope of possibility. That envelope should be even easier with AL80s.Yeah you're right. I only use AL80/40 as stages. These would probably only made things worse. Maybe I have to get used to it but it's so uncomfortable that I don't have the freedom to move around
I'm basically your height but heavier. Shorter doubles like HP100s put me in a very head heavy position that affects my stability in the water. You may want to try a tail weight instead of a v-weight. I'm also diving in 39f / 4c water so similar conditions / thick undergarments.
I'm not saying this is your problem but it is very common for short people although I realize you mentioned side to side movement. Try an experiment if you haven't..if you're in proper trim with your legs up and don't move at all do you want to go head forward? I admittedly fought this for long time. The solution for me was longer doubles combined with a tail weight.
Make sure your waist strap and crotch strap are snug. This definitely will help stabilize the doubles. Like others, I keep my shoulder straps loose to help drop the tanks on my back. It does take some getting used to.
Stages can absolutely exacerbate this problem if your stability is off in the first place.
I'm not saying this is your problem but it is very common for short people although I realize you mentioned side to side movement. Try an experiment if you haven't..if you're in proper trim with your legs up and don't move at all do you want to go head forward? I admittedly fought this for long time. The solution for me was longer doubles combined with a tail weight.
Make sure your waist strap and crotch strap are snug. This definitely will help stabilize the doubles. Like others, I keep my shoulder straps loose to help drop the tanks on my back. It does take some getting used to.
Stages can absolutely exacerbate this problem if your stability is off in the first place.
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