Single Tank Adapter and Ditchable Weight

[judedude]

OK, so I have a Halcyon BP/W rig (SS BP = 6lb) and Single Tank Adapter = 6lb diving an AL 80 and a 3mm suit, not yet OW tested. This rig is very comfortable in the pool but I have concerns about the lack of ditchable weight. I require zero additional weight to achieve neg buoyancy in the pool with the wetsuit on. Would it be more advisable to remove the STA and replace the 6lbs with a system such as the Halcyon ACB or a traditional weight belt? OR, is it enough for me to test in the pool with no wetsuit, no air in the wing, and a full tank and see if I can swim to the surface with it? I imagine that if I went to a 7mm suit, I would need both the STA and the weight belt. I'm just trying to think through the weighting before I get in OW. I've gotten recommendations in both directions.

 

[Geoff_H]

I would think about what situations you will need to ditch weight.

For me, I mostly dive with no ditchable weight and am happy to do. This is because I can swim up from depth even with my wing deflated.

If I am on the surface, I could either remove the harness although or use my DSMB as redundant bouyancy.

I have pockets on my tank bands that sometimes contain weight if I am diving an aluminium tank and using a 5mil wetsuit. If I needed to I could take the rig off, release the weights and put it back on but I can't think of a situation where I would need to do this.

So, I am comfortable without easily ditchable weights - I love not having to wear a weightbelt.

 

[rawls]

May want to try an aluminum backplate which will shave off a bit of weight. I am also a bit negative when my bladder is empty. I use a SS backplate but am going to get an aluminum soon. In any event I have to add a little air in my bladder when I hit the water or I will begin to descend immediately, not rapidly though. This isn't a problem since I am adjusting my buoyancy to maintain neutral at whatever depth I am at. The problem is what if I have a malfunction in my bladder. Then there is the redudancy of a dual bladder. I definitely see where you are coming from and being I need no additional weight with the SS BP I am getting the aluminum as an alternative. But I also use steel 120 singles and steel double 80's. When you have less air in your tank...obviously you will be a bit less negative if not a bit positive. Then there is your dive buddy in case of a failure...What happens if you have a failure and no dive buddy...I guess you do the best you can to ascend until you are neutral again and can swim the rest of the way...I know there are those who can come up with some alternative suggestions. I wouldn't mind hearing them too...But I don't know a sure fire way to create ditchable weight when you don't have any to ditch.

 

[judedude]

I've run through buoyancy calculations. The reality is that my wetsuit really doesn't provide a lot of buoyancy, and so, won't become dramatically less buoyant at depth. That's why I thought a no wetsuit test at full weight in the pool would be ideal. But, it's a bit different being at 80' and having to swim to the surface than being at 16'. I guess Geoff's suggestion of using the SMB for lift works as long as there is a shallow enough bottom I don't mind being there for a minute or so. Pendng the pool test, I may remove the tank adapter weight and replace with ditchables knowing that if I went to a more buoyant suit, I could use both.

 

[Geoff_H]

Pendng the pool test, I may remove the tank adapter weight and replace with ditchables knowing that if I went to a more buoyant suit, I could use both.

I like your thought processes... even though we may come to different conclusions anyone who is thinking through the options, risks and benefits and coming to a conclusion that works for them is doing well in my book.

I should add I was diving a single-steel 108 (big heavy steel tank), no wetsuit and no weightbelt in Truk a couple of months ago. I took that chance to check I could swim up with an empty wing as I think this is the most negative I will be able to get without doubles or stages.

I'm thinking of getting a lightweight backplate just for travel to tropical destinations now.

 

[judedude]

Geoff,

Thanks for your advice. In the pool with no wetsuit, empty BC and a full tank I had no problems swimming against the weight of the rig. At the surface, I was able to get positive by manually inflating my SMB. I feel confident in being able to handle a buoyancy failure, especially with the additional buoyancy of my wetsuit at the surface. If I add any additional weight for a thicker suit, it will be ditchable. And, of course, I'll try the test again if I change my tank setup. Thanks again.