Katana 2 tanks uneven

[TuckerM80]

Just as the title says, using a Katana 2 dual bladder, no matter what tanks I use, bolt snaps, snap bolt location on tanks, opposing and non opposing valves, tighten bungees, the left tank will sag down. I’ve tightened every part of the harness so that it’s tight, lower tank mounts are even on the waist belt, and the crotch strap is tight and I’m pretty much stumped at this point. My dive buddies who dive katana 2 single bladder can’t figure it out either. Any advice would be greatly appreciated, thank you scuba board fam !!!

 

[grantctobin]

Just as the title says, using a Katana 2 dual bladder, no matter what tanks I use, bolt snaps, snap bolt location on tanks, opposing and non opposing valves, tighten bungees, the left tank will sag down. I’ve tightened every part of the harness so that it’s tight, lower tank mounts are even on the waist belt, and the crotch strap is tight and I’m pretty much stumped at this point. My dive buddies who dive katana 2 single bladder can’t figure it out either. Any advice would be greatly appreciated, thank you scuba board fam !!!

Can you post an image of your bottles, the rigging on the bottles, how you’re routing the bungee, and ideally an underwater picture? Are you clipping to sliding rings or the clinically massive stock square drop Ds? Which bottles?

 

[TuckerM80]

Can you post an image of your bottles, the rigging on the bottles, how you’re routing the bungee, and ideally an underwater picture? Are you clipping to sliding rings or the clinically massive stock square drop Ds? Which bottles?

 

[TuckerM80]

Can you post an image of your bottles, the rigging on the bottles, how you’re routing the bungee, and ideally an underwater picture? Are you clipping to sliding rings or the clinically massive stock square drop Ds? Which bottles?

 

[TuckerM80]

Can you post an image of your bottles, the rigging on the bottles, how you’re routing the bungee, and ideally an underwater picture? Are you clipping to sliding rings or the clinically massive stock square drop Ds? Which bottles?

I am clipping to the factory square drop D’s. Using steel HP120’s. The right bottle is always perfect, but the left hangs as you can see in the in water pictures. Changing bungee routing, tightening or adding slack changes nothing for the lower mount. I tried my buddies LP 108’s and the left tank sagged as well. The actual “harness” seems to move independently from the bladder quite a bit

 

[grantctobin]

I am clipping to the factory square drop D’s. Using steel HP120’s. The right bottle is always perfect, but the left hangs as you can see in the in water pictures. Changing bungee routing, tightening or adding slack changes nothing for the lower mount. I tried my buddies LP 108’s and the left tank sagged as well. The actual “harness” seems to move independently from the bladder quite a bit

The “all in” fix everything at once answers:

-Ditch the dive rite stage rigging. Is inappropriate for sidemount. Jubilee band, short paracord, boltsnap on the bottom. Top you can leave a paracord leash if you need to jump off of a boat and then unclip this leash once underwater. (15-25%)
-Switch to opposing valves with the isolation post. Assuming your bungees are the same length, this is the probable cause of most of your issues. It is not possible to route equal length bungees the same way with the valves you have. (70-80%)
-I think your drop Ds are not equidistant from the back plate, but this is likely sub a cm (5%).

If it is not any of the above, there is a chance that it is a combination of your regulators and the routing of said regulators that are causing the issues. Fifth port regulators whilst using the traditional Bogarthian rigging may help. Lastly, you could use a fish or luggage scale to ensure each of the bottles are of similar buoyancy. Those valves each have different weights, and some pairs of HP120s themselves that are easily a pound different in buoyancy.

I would consider running a bungee tightly between the drain grommets at the bottom of the wing and threading this through the crotch strap. This will greatly limit the wing shaking around relative to the harness. Image below of someone else’s wing.

 

[Kendall Raine]

I don’t dive a Katana but have on occasion had a droopy bottle. Typically using rented tanks so suspect mismatched buoyancy. If you’re sure that’s not the issue have you tried a different harness? Can’t say that’s the cause (not sure why it would be) but just seems the only variable you haven’t solved for.