Trim issues - Rolling over bp/w + heavy tank

[andrethediver]

Need some help sorting trim issues. I am a recent convert to bp/w setup and dive with 30lb wing, aluminum bp and a steel? tank adapter and 15l aluminum tank. No additional weight and no exposure protection beyond a rash guard. First 45 minutes of every dive, while neutral and motionless this setup seems to tend to roll a bit sideways and over (tank towards the bottom) even though the harness is fully cinched down and nothing is loose or apparently unbalanced. What could be the cause? Thanks.

 

[loosenit2]

what kind of wing, donut or horseshoe? when you say harness is fully cinched down what exactly do you mean?

 

[Rukkian]

Need some help sorting trim issues. I am a recent convert to bp/w setup and dive with 30lb wing, aluminum bp and a steel? tank adapter and 15l aluminum tank. No additional weight and no exposure protection beyond a rash guard. First 45 minutes of every dive, while neutral and motionless this setup seems to tend to roll a bit sideways and over (tank towards the bottom) even though the harness is fully cinched down and nothing is loose or apparently unbalanced. What could be the cause? Thanks.

Are you saying the kit rolls off your back, or you are being turtled? If you are just getting rolled over, you may need to add a bit of weight (just a lb or 2) in front and add a bit of air to the wing. I have a ss bp and al80, so a bit different. Having a small amount of air in the wing helps to keep you in trim.

 

[boulderjohn]

A couple years ago a student who had the same problem (and I have had more than one) laughingly said my advice to him was like an old Vaudeville joke. The man goes to the doctor and says "It hurts when I do this." The doctor says, "Don't do that." In this case, as usual, the advice worked. He stopped doing it.

In every case I have seen, it is like learning to ride a bike. It takes a few rides before getting comfortable with the balance, and then, very suddenly, things are just fine. Now, you may have an unusual case where something in your gear setup is causing the problem, but in every case I have dealt with, it is just a matter of getting used to it.

 

[grantctobin]

I’ll go with maladjusted harness.

 

[CT-Rich]

I am with Boulderjohn. All your weight is behind you. You are going to roll. There are scuba ninjas who are going to give great advice about moving weights to adjust trim. Unless it interferes with normal swimming, you will stop thinking about it and never notice it again.

 

[MrVegas]

I'm no expert, but my odd collection of tanks does include one that is very negatively buoyant. I definitely notice the difference with that one. The most negative part of the setup wants to be on the bottom. At the beginning of the dive, your tank is most negative -- 45 minutes later you probably have a few pounds less on your back. That's just a guess.

 

[AfterDark]

Need some help sorting trim issues. I am a recent convert to bp/w setup and dive with 30lb wing, aluminum bp and a steel? tank adapter and 15l aluminum tank. No additional weight and no exposure protection beyond a rash guard. First 45 minutes of every dive, while neutral and motionless this setup seems to tend to roll a bit sideways and over (tank towards the bottom) even though the harness is fully cinched down and nothing is loose or apparently unbalanced. What could be the cause? Thanks.

A clue maybe in the bold text, there is less air in your tank therefore less weight after 45 min of diving which will change your center of gravity making you less top heavy. If it were my rig I'd try adding 2lbs to my belt/harness near my stomach. However 2lb for me diving with a 7MM FarmerJohn wetsuit isn't the same for you with a rash guard, but with a 30lb wing it shouldn't be a big deal. Two pounds of rocks in a weight pocket you can ditch after 45 min may work for you also.

Or as @boulderjohn posted it may just take a few dives to get accustom to and you'll start compensating for it yourself over time. So you can wait and act later if need be.

 

[Lorenzoid]

I had the same problem when I first switched to a BP/W, and my instructor used the same analogy mentioned above: it's like learning to ride a bike. Your single tank wants to be your keel and roll you over. It's a matter of balance. With double tanks, the weight is distributed a bit more evenly, so many people find doubles to feel more stable.

 

[inquis]

I agree with others that you'll probably get used to it. In the meantime, the minor corrections will probably cause you to creep forward when trying to be motionless. Use this time to work on your back kick.