Trim Issues

[Forbin's Descent]

But I stand by what I said. Side-mount configuration certainly resolves the issue he is having. It improves the trim, is better for your neck, and is by no means "inferior" to back-mount.

Not necessarily. Don’t get me wrong I prefer sidemount but he can have the same issue with sidemount and will still need to properly weight himself and distribute it well.

 

[stepfen]

Steel tanks are a problem solver. It will take weight off of your waist, and much, much easier to trim out a drysuit.

I have about 50 drysuit dives over 3 winters. I always dive with a 15lt steel tank.
I've managed to get my trim in the horizontal plane ok(-ish). It is not perfect yet - I would have to dive more frequently to perfect it, but anyway it is quite ok the way it is.
For me what works is this: 2kg on the upper tank band, 3-4kg on my belt.

The problem is that a lot of the weight (tank + the 5-6kg of lead) is on my back, hence if/when I roll a bit to the left or right I fill like I am going to roll upside down like a turtle on its back. When I am horizontal everything seems to be ok, but if I roll a bit I become unstable and my back/tank wants to sink.
Any suggestions how to correct this?
I've tried to have my belt weights on my front instead of my back. It helps a bit but not much as most of the weight (tank+2kg) is still on my back. Not to mention that I don't really like it this way because lead blocks interfere with the waist belt of my BPW (buckle, shears, knife, long hose etc).
Anything else I can try?
Interestingly, with wetsuit (same tank, but only 2-3 kg lead) I don't have this problem - I can comfortably slowly roll 360 degrees, or comfortably stay at say a stable 45degrees roll to either left or right.

 

[The Chairman]

if/when I roll a bit to the left or right I fill like I am going to roll upside down like a turtle on its back.

This is a great point. Be sure to position any weight on the diver side of the tank. If you arch your back correctly, you'll feel it on your butt, and that's OK. But the best practice is to use steel tanks. I dont dive exposure protection anymore, but I used to. When you're built like a manatee, you get to dive like one.

 

[Arkman]

I dove again this weekend. It was a little better, partly because I was back to my steel tank I think. I still had some listing issues but it was a little better. That said, I really noticed that my BC is trapping air somewhere by my left shoulder. I don't mean in the bladder. I mean I think some of my bubbles from my exhale are getting trapped somewhere back by that shoulder. When I rotate side to side all the sudden you'll hear a rush of bubbles coming out. This after messing around a bit I could tell this was part of the issue. It is a big reason why my buoyancy seems to be an issue lately I think. I feel like I am in good buoyancy for a minute but then I'm going up too much. I would try to dump BC air and then I'd drop back down a bit. But then as soon as I'd roll a bit those bubbles would come out and then I'd need to add more BC air to be buoyant.

This is so weird. I've dove this BC a lot and never noticed this before, but I also hadn't really been working on buoyancy. I will say earlier this year I was (unintentionally) using my drysuit for buoyancy a lot more and almost never used the BC. So that explains why I didn't notice it as much until now. Now I'm trying to balance use of the drysuit and BC and using the BC a little more and I'm noticing these issues.

One more thing to look out for with the BC you are using is it has U shaped bladder and it will trap air in the bottom corners. This can make you roll or end up with too much lead because you are not getting all the air out.

I do feel like I really have to get myself upright to effectively dump air out of this BC. I can get some out with my shoulder dump but I can almost never manage to get any out of the butt dump. Not sure why. Half the time I can't locate the damn dump valve on the butt. I know where it is, I just can't get ahold of it in my gloves.

 

[BlueTrin]

I dove again this weekend. It was a little better, partly because I was back to my steel tank I think. I still had some listing issues but it was a little better. That said, I really noticed that my BC is trapping air somewhere by my left shoulder. I don't mean in the bladder. I mean I think some of my bubbles from my exhale are getting trapped somewhere back by that shoulder. When I rotate side to side all the sudden you'll hear a rush of bubbles coming out. This after messing around a bit I could tell this was part of the issue. It is a big reason why my buoyancy seems to be an issue lately I think. I feel like I am in good buoyancy for a minute but then I'm going up too much. I would try to dump BC air and then I'd drop back down a bit. But then as soon as I'd roll a bit those bubbles would come out and then I'd need to add more BC air to be buoyant.

This is so weird. I've dove this BC a lot and never noticed this before, but I also hadn't really been working on buoyancy. I will say earlier this year I was (unintentionally) using my drysuit for buoyancy a lot more and almost never used the BC. So that explains why I didn't notice it as much until now. Now I'm trying to balance use of the drysuit and BC and using the BC a little more and I'm noticing these issues.


I do feel like I really have to get myself upright to effectively dump air out of this BC. I can get some out with my shoulder dump but I can almost never manage to get any out of the butt dump. Not sure why. Half the time I can't locate the damn dump valve on the butt. I know where it is, I just can't get ahold of it in my gloves.

For your shoulder dump, you can ask someone to look at you when you do it to check if you bring the air bubble in the right location.

I don’t know your BC, with mine if I dump from the inflator I put the inflator behind my head and a bit upwards, and go slightly trim heads up (or flattish) that bring the air bubble usually in the right location.

For dumping from your butt, you need to be heads down and incline on the side a bit to bring the butt dump high.

To find the dump valve, don’t look for the rope, look for the plastic circle itself, grab it and either roll your finger around to catch the rope or just clasp and close your hand on the circle to grab the rope.

 

[rongoodman]

hen I rotate side to side all the sudden you'll hear a rush of bubbles coming out. This after messing around a bit I could tell this was part of the issue. It is a big reason why my buoyancy seems to be an issue lately I think. I feel like I am in good buoyancy for a minute but then I'm going up too much. I would try to dump BC air and then I'd drop back down a bit. But then as soon as I'd roll a bit those bubbles would come out and then I'd need to add more BC air to be buoyant.

You aren't hearing "bubbles coming out", you're hearing air moving from one side of the bladder to the other behind your head, and if you start adding or dumping air every time that happens, it's no wonder you're having issues. If you're not really neutral and flat in the water you might be kicking in order to maintain your position in the water column and when you get distracted and stop kicking, you sink. I never use the shoulder dump anyplace except on the surface. I go a little head down and dump air from the rear OPV, easy peasy. That also puts me in position to kick down if I need to. Doing the same at the safety stop will let you feel if there's more than a minimal amount of air back there. If there is, you're overweighted.

 

[Arkman]

You aren't hearing "bubbles coming out", you're hearing air moving from one side of the bladder to the other behind your head, and if you start adding or dumping air every time that happens, it's no wonder you're having issues. If you're not really neutral and flat in the water you might be kicking in order to maintain your position in the water column and when you get distracted and stop kicking, you sink. I never use the shoulder dump anyplace except on the surface. I go a little head down and dump air from the rear OPV, easy peasy. That also puts me in position to kick down if I need to. Doing the same at the safety stop will let you feel if there's more than a minimal amount of air back there. If there is, you're overweighted.

I think this could be some of what i'm hearing, but both Me and My buddies have seen the bubbles come out.

 

[BlueTrin]

I think this could be some of what i'm hearing, but both Me and My buddies have seen the bubbles come out.

Are you sure it’s not the inflator connection leaking or a hole in your BC?

 

[Arkman]

Are you sure it’s not the inflator connection leaking or a hole in your BC?

It is possible, but I really dont think so. I can inflate the BC fully and not get any bubbling just sitting there. I also did a spray test with soapy water. No sign of leaking.

 

[VikingDives]

It is possible, but I really dont think so. I can inflate the BC fully and not get any bubbling just sitting there. I also did a spray test with soapy water. No sign of leaking.

The bubbles you're seeing are probably from the air trapped in the fabric of the BCD coming out at the beginning of the dive.