Question Tried BPW for the first time, but kept having balance (trim) issues?

[jay040]

I rented a Halycon BPW setup to try out yesterday - was in a drysuit, and a Halycon BPW with steel backplate and a steel tank. I am not certain, but I believe the shop said it was a 40lb wing. I made sure the wingnut fasteners on the backplate were as tight as I could hand-turn them prior to kitting up. When I was underwater, if I leaned slightly to the left to look over my right shoulder to check on my partner, I felt the tank rock to the left, and it would throw off my balance. I had to do a little shimmy to try and center it. It would also shift to the right if I tilted that direction. I started to do a little shimmy if I added any air to the wing, just to try and make sure that one side didn't get more inflated than the other, but I never got close to full inflation of the wing. The deepest we went was 20ft.

Is this just an issue with the wing is not mostly inflated? Did I need a 30lb wing instead? Should I have used a wrench to make sure the wingnuts were tighter than just my hand tightening? I realize it was my first time to try BPW but it sort of turned me off of it. I've never had the tank rocking issue with a normal BC.

Thanks for any suggestions.

 

[parzdiver]

If the tank was rocking, there was a fastener issue. The tank should be solidly connected to the backplate. A larger than needed wing my "taco" a bit, but wouldn't cause the shifting you mentioned.

Was it the tank shifting or was the entire backplate/wing/tank assembly shifting?
If it was the tank, was there a single tank adapter between the tank and the plate or were the straps for the tank through the wing and plate? I have both configurations, in the second there are typically some sort of stabilizer on the wing that keeps the tank stable.

 

[diver42]

I rented a Halycon BPW setup to try out yesterday - was in a drysuit, and a Halycon BPW with steel backplate and a steel tank. I am not certain, but I believe the shop said it was a 40lb wing. I made sure the wingnut fasteners on the backplate were as tight as I could hand-turn them prior to kitting up. When I was underwater, if I leaned slightly to the left to look over my right shoulder to check on my partner, I felt the tank rock to the left, and it would throw off my balance. I had to do a little shimmy to try and center it. It would also shift to the right if I tilted that direction. I started to do a little shimmy if I added any air to the wing, just to try and make sure that one side didn't get more inflated than the other, but I never got close to full inflation of the wing. The deepest we went was 20ft.

Is this just an issue with the wing is not mostly inflated? Did I need a 30lb wing instead? Should I have used a wrench to make sure the wingnuts were tighter than just my hand tightening? I realize it was my first time to try BPW but it sort of turned me off of it. I've never had the tank rocking issue with a normal BC.

Thanks for any suggestions.

Sometimes there’s a spacer on the bolt and also a washer. You want the washer (if you use it) on the side of then backplate closest to the wingnuts. If you leave it in the tank side you’ll have the problem you describe, because there isn’t a flat connection between everything. Maybe it’s something else, but this is my guess.

 

[jay040]

Was it the tank shifting or was the entire backplate/wing/tank assembly shifting?
If it was the tank, was there a single tank adapter between the tank and the plate or were the straps for the tank through the wing and plate? I have both configurations, in the second there are typically some sort of stabilizer on the wing that keeps the tank stable.

I'm pretty sure it was the tank. I don't remember for sure if there was an adapter between the tank and plate or if the straps went through the wing and plate. I plan to rent again around New Years, so I'll talk through the issue with them and do more extensive checks prior to checking out the gear. Thans for giving me a lead on what to look for.

 

[Eric Sedletzky]

The Halcyon plates have a really steep bend and adding a STA on top of that puts the tank way out off your back which will throw off your center of gravity. On top of that it sounds like the nuts on the STA were not tight enough or set up wrong so you might have had a little bit of tank wobble.
Try a flatter plate and one that has slots in the wing and plate so you can eliminate the STA. Almost all other brands of wings have anti tank roll cushions which eliminates the need for a STA, and also combined with a flatter plate gets the tank snugged down closer to your back for better stability.

 

[jay040]

The Halcyon plates have a really steep bend and adding a STA on top of that puts the tank way out off your back which will throw off your center of gravity. On top of that it sounds like the nuts on the STA were not tight enough or set up wrong so you might have had a little bit of tank wobble.
Try a flatter plate and one that has slots in the wing and plate so you can eliminate the STA. Almost all other brands of wings have anti tank roll cushions which eliminates the need for a STA, and also combined with a flatter plate gets the tank snugged down closer to your back for better stability.

Thank you

 

[parzdiver]

Sometimes there’s a spacer on the bolt and also a washer. You want the washer (if you use it) on the side of then backplate closest to the wingnuts. If you leave it in the tank side you’ll have the problem you describe, because there isn’t a flat connection between everything. Maybe it’s something else, but this is my guess.

A friend of mine bought a BP/W with an STA and the idiot, I mean person, that put it together put the lock washers between the STA the wings. When setting everything up for he first dive with the gear, we noticed the wobble..... Fortunately we got it corrected before hitting the water. The assembler was the same guy that sold him the setup with an STA, when the wing (Hollis) came with a stabilizer. Not sure why, but my buddy still uses the STA..... SMH