New to BP/W - Weighting Issues

[bkilleen]

Bit of background - Just started diving with a BP/W setup. Bought an older OMS IQ harness with SS backplate from a friend, added a Scubapro XTek wing and STA to complete the kit.

I was diving a Scubapro Knighthawk with 6 lbs of lead with my steel 119 or 130 cylinders with a 7mm wetsuit in cool Canadian fresh waters.

I went out for my first quick dive with the BP/W, but because I knew that the SS backplate was quite heavy itself, weighing in at around 6-7lbs, I didn't add any lead. I found myself struggling to remain neutral and my trim was way off; the problem was that I seemed to be really heavy. Even at the end of the dive I was able to descend with no issues at all.

I'm guessing that the SS backplate along with the STA is a couple of pounds more than I would typically need. I'd hate to get rid of the SS backplate because I would like to use it too weigh-up when diving dry, but I can't think of anywhere else to shed weight from. Will likely need to invest in an AL backplate for when diving my usual gear.

Thoughts?

 

[RainPilot]

The AL backplate will probably end up being the way to go. In the meanwhile, how heavy is too heavy? If you are at the end of the dive are you sinking with full lungs, empty BCD? If you are only a little over, then there are some very lightweight STA options that can shave a pound or 3 off.

 

[CptTightPants21]

SS plate is -6,

STA is just an STA right no internal weight included you don't realize?

Trim is a plate and tank placement issue, not necessarily a SS BP issue.

The SS plate removes the 6lbs of lead you were using. Add in the STA and remove the natural buoyancy the Knighthawk I still can't see how you were extremely overweighted--maybe just not used to how much air was needed in the wing.

An AL might be what you need, but I would do another 10 dives before making that judgment call.

Can you explain "Could descend at the end of the dive no issue at all"? I am not understanding the problem.

 

[bkilleen]

@RainPilot I just felt that I needed too much air in the wing to stay neutral, and that as I went through various depth changes, I needed to play with that volume too often.

@CptTightPants21 Yes, STA is just a bare STA, but I think it comes in at around 2 lbs.

And to clarify - To check my weight I did a quick self-test at the end of my dive. With about 900 PSI, and empty wing, I was able to descend with ease, even with a full set of lungs if I wanted to. Generally, with my old setup, I was able to hover easily with that volume of air and an empty BCD, and would need to really empty my lungs to descend.

That said, perhaps you're right - might not be used to the new setup just yet.

Thanks for the comments!

 

[herman]

"That said, perhaps you're right - might not be used to the new setup just yet."

Nope, you are overweighted and it's not that uncommon with a steel BP. I can't dive a steel plate in warm fresh water, with no buoyant thermal protection, it will overweight me by several lbs (I typically dive with no extra weights) and it overweights me by a couple of pounds in warm salt water. Those who advocate BPs, esp steel ones, don't seem to realize that some of us can't use the extra weight it adds.

 

[tbone1004]

I'm with Herman, in a kydex plate, no STA, AL80, and a 3mm shorty with 3mm hooded vest, I am close ish to neutral. In the salty stuff I would switch to steel.

It doesn't surprise me that you would be 2-4lbs heavy in that setup, but not based on the weight you needed in the SP jacket, more that you were probably overweight in that but it was trapping air somewhere. Unfortunately it doesn't appear that you have any place to shave lead off. Switching to a less negative backplate wouldn't hurt, especially if you are going somewhat deep in a 7mm so you don't compound the overweighting, but if you're staying above 50 ish feet I personally wouldn't buy another plate and harness because of it.

Which X-Tek wing did you buy? Some of them have strange shapes

 

[bkilleen]

I pulled the trigger on an AL backplate the other day, and I'm hoping to dive it later this week. I took a quick test dive with it in my pool; it will need a couple minor adjustments, but overall it feels pretty good. Now I just need to determine how much lead to take with me.

@tbone1004 I have an X-Tek 30 donut wing. Seems pretty standard shape-wise to me.

Thanks again for the comments.

 

[Bob DBF]

SS plate is -6,

STA is just an STA right no internal weight included you don't realize?

The STA that was included when I bought my Hammerhead plate (6#) was almost the weight of the plate at just under 6#, the lightweight STA was about 2#. I found I did not like using a STA, not just due to the weight, so now I don't.



Bob

 

[Scubanoobi]

A plate might not be for everyone, I dive a DiveRite Transpac (soft pad instead of a plate), 7-10mm of neoprene, steel tank in the same waters as you, and I'm still negative at the end of the dive. Even with a drysuit I don't use any weight. I don't think I could go with a SS or AL backplate.

 

[bkilleen]

@Scubanoobi True - I guess some people are just naturally negative and don't need the weight a backplate has.

With the Knighthawk I was frequently still slightly negative at the end of dives, and I certainly don't mind that. However, with the SS backplate I just found that it was too heavy, and I had to inflate/de-flate my wing too often; at least, more so than I ever had to with my other BCD. That said, it did take a few dives to get my weight just right with the Knighthawk to the point that my buoyancy felt pretty much perfect throughout the dive at different depths, perhaps that will be the case with the BP/W configuration as well.