Help balancing new BP/W

[jzipfel]

Hello all:

I purchased a HOG BP/W from Jim and finally got my first couple dives in this weekend. While I really enjoyed the fit, there were some "operational" issues that I was looking for some help:

My Setup:
I historically dive dry in Puget Sound, and when I was using the shops rental AquaLung BCD, my logs show I was wearing 24 lbs of weight on a weight belt and also had 2 ankle weights (not included in total weight).

This dive had the BP/W with 2-4# weights attached to lower cam bands and 2-4# weights attached to waist belt. Also had ankle weights. This would mean I was weighted to 22lbs (minus ankles) vs 24 lbs. I went 2# less given no buoyancy of BP/W vs BCD.

OK, now my issues:

1) i needed 4 lbs weight in addition to the 22# i started with to bring me up to a total of 26 lbs. I had hoped to get by with a little less weight. My body weight has actually dropped by 10# from the last time I dove dry but otherwise all other equipment was identical. I'm trying to figure out why I needed more weight to be neutral at 15 feet. Thoughts??

2) Rotation of rig. What was most disturbing, but not scary, was the amount of roll while underwater. It seemed every move of my body right to left or left to right would cause me to want to "turtle" and turn face up. I never actually rolled, but sure would have if I let it. I tried using the wing primarily for buoyancy on first dive, then tried using dry suit primarily for buoyancy on the second dive. No discernible effect on this roll. I did get pretty good at a swift move of the hips to counter this roll effect though.

Having read through hundreds if not thousands of posts on BP/W before I made the leap, I never saw this come up. So, here I am. Any thoughts on a cause and more importantly a solution. Should I move all my weight to my front?

Thanks in advance for any help or suggestions

 

[bradells]

Is the harness shoulder straps symmetrical (ie, the same length)?

I'm assuming your diving a single tank (due to the amount of weight required), are you using a STA as well, or just using the slots? If its the slots, you might have not used the same on both sides of the band, or differing between the bands. Been there, did it once, and it sucked.


Is your waist band/crotch strap tight enough?

Also, your saying you haven't dove a drysuit in a while, are you keeping more air in it than usual? Does the drysuit still fit well after loosing the weight?


Just some thoughts,


BRad

 

[tbone1004]

too large of a bubble is the only thing I can think of. With a BP/W you shouldn't have needed the trim weights because it spreads the weight out. You have 8lbs of negative ballast on the Hog rig with SS cam bands assuming no STA, you are probably 1-2lbs positive with the Aqualung, so yes you should have been able to remove 2lbs or so from total ballast.

What concerns me is that you had 8lbs on your waist area plus however much the ankle weights are, what on earth does your trim look like? Even in a drysuit you shouldn't need that much weight down low. The rolling is due to the suit having too much air in it. You float, you float a lot in a drysuit, your plate and the tank sink especially when there is 8lbs on there, so physics dictate that floaty stuff goes up, sinky stuff goes down hence the tendency to want to roll. If you have more air in the wing, you want to roll less because you are now being suspended from the rig instead of you trying to flip the rig over.

Suggestions

Switch to gaiters instead of ankle weights if you're trying to keep your feet from getting too floaty, consider Hollis F1 bat fins or Scubapro Jet fins because it will put weight on your feet as well, get away from ankle weights, don't need them.

Take the weight off of the cam bands, that is your real problem right now. You have 8lbs of lead sitting at minimum 4 inches off of the back plate and much higher than your body so those 8lbs are what is really trying to flip you over. If you don't want them on your belt, you can get crafty with trying to make plates for that harness which will help to keep the weight down low. Deep Sea Supply makes great plates, that should fit but you will have to drill 2 maybe 3 holes per side into the plate to get them to bolt on.

Otherwise, look into making or buying a weight harness or suck it up with a weight belt unfortunately. You have to get into steel tanks, even if it is buying some cheap LP72's on craigslist, those alone will allow you to take 5lbs off of your belt if you're diving aluminum tanks. You have to try to dive with less air in your drysuit if possible, sounds like you have an ill-fitting suit in the legs which is causing too much air to head up there, see if a buddy has some gaiters or invest in some, or make some. You can wrap your legs in ace bandages after the suit is on if you don't want to get some gaiters. This will help to keep the air down in your suit instead of at your feet. That alone will rid you of the ankle weights and like 2-3lbs of lead by keeping wasted air out of the bubble.

Get the weight off of the cam bands first and report back, you'll be surprised how much of a difference that will make.

 

[Lorenzoid]

. . .
2) Rotation of rig. What was most disturbing, but not scary, was the amount of roll while underwater. It seemed every move of my body right to left or left to right would cause me to want to "turtle" and turn face up. I never actually rolled, but sure would have if I let it. I tried using the wing primarily for buoyancy on first dive, then tried using dry suit primarily for buoyancy on the second dive. No discernible effect on this roll. I did get pretty good at a swift move of the hips to counter this roll effect though.
. . .

I seem to recall having seen the issue of "roll" mentioned before, but it has long surprised me that it isn't mentioned more often. Stability in the roll direction (not to mention pitch direction) was a HUGE problem for my wife and me to overcome when we switched to BP/W rigs from traditional BCs a year or so ago. (We dive in wetsuits, by the way.) Yes, I would turn turtle, or find myself starting to pitch headfirst. And this is AFTER my GUE Fundies instructor carefully helped me adjust my weighting for proper trim and buoyancy. It took a lot of practice for me to finally get stable--it indeed seems to involve balancing and a barely perceptible amount of finning to compensate. I don't understand why some people have these problems and others say that the first time they dove in a BP/W they were rock solid. Getting used to a BP/W was not easy for me.

 

[tbone1004]

you shouldn't have to fin in a plate, if you are you aren't positioned properly in your body. The right feel occurs if you lay prone on the floor, bend your legs 90* with your arms out in front if you hands touching


like that

and arch your back so your knees and elbows come off the ground. It feels weird, but that is how it is supposed to feel. That is proper trim position and will keep your body prone. Moving your torso every so slightly can be enough to induce a front or back roll, no other body part has to move and you can induce pitch. You don't need your fins. Jet fins help quite a bit with plates though since they give you a little extra weight at your feet, but most of us can hover motionless in a pool without fins on as well.

If you are prone to rollw, that is usually a function of the wing being too full and you need to remove weight. What happens is if the wing is too full, as soon as you start to roll, the air shifts from one side very quickly to the other side which throws the center of balance off and makes the roll worse, you then end up on your side and inertia takes you the rest of the way to your back because floaty things float, sinky things sink.

 

[Lorenzoid]

Dunno about the OP, tbone, but speaking for myself, only after many many hours practicing am I now able to hover in trim without moving out of place, as in your pic. But it does take some amount of compensation with the fins/legs acting as counterweights--moving a leg in or out a tiny amount like a fulcrum now and then to counteract a tendency to pitch or roll (not yaw). I suspect part of the issue is that the wing is never 100% devoid of air--there is always some small bubble in there to move around. My instructor said this is normal, and you just have to learn to balance, like we did when we were learning to walk. I just don't know why more people don't mention this issue.

 

[tbone1004]

you will always have air in the wing. You have to. It compensates two things. Weight of air in the tank, and the change in buoyancy inherent in wetsuits. Diving dry eliminates the latter, but on a single tank you have at minimum 5lbs of weight changing on a normal dive, so at the beginning you have at least 5lbs of air in there.

You don't have to move your fins when they are acting as counterweights, once they are in place you are balanced. Finding that takes some finesse and yes it takes many many hours of doing it to get it right, but that's why number of dives doesn't matter and I would rather dive with someone who has 200hours in a pool at 10 open water dives than a diver who has 200 dives but only 10 hours in a pool. Odds are the guy who has spend time in the pool is much better despite having a small number of dives.

my apologies about yaw, clearly not thinking this morning. Was talking to a student last night who can't kick in a straight line while doing navigation so had that in my head all morning.

 

[jzipfel]

Thanks everyone. It's kind of funny asking questions on a forum. You think you provide details and realize how much you left out

I'm 5'7" and 160.

I was diving steel single no STA

Drysuit was a laminate with quilted fleece undergarment. I think the undergarment was thicker this time possibly accounting for additional positive buoyancy

I bend and burp the suit before entering water so was pretty empty. BP/W was emptied prior to descending

I only adder air to suit twice and fractions of a second for primary purpose of squeeze and not buoyancy.

Not indicating I'm any good but other divers I was with with 20+ years diving and did not know me asked how long I had been diving and thought I had been diving for years as my trim was really nice. So I'm not flailing in the water

Ankle weights are a short term solution while I get dialed in

Any who I'll be back in the water in a couple weeks with my son who will be in the same set up for the first time. We'll see how he fares.

I'll focus on ensuring al air is out of suit and bladder

 

[tbone1004]

If you're doing it that way the weight should be fine, but you're awfully skinny to need that much lead. Either way, get the lead off of the cam bands and onto the belt and you'll be much better off

 

[dumpsterDiver]

If you're doing it that way the weight should be fine, but you're awfully skinny to need that much lead. Either way, get the lead off of the cam bands and onto the belt and you'll be much better off

Agreed. It is not complicated, for maximum stability, you want the lead to be below your body and the buoyant wing to be above your body. Although that may not be entirely practical, getting the lead on your hips or even more forward of that (below your body) should help.

Do you have ahorseshoe shaped wing? I had one and really disliked it. Air goes to one side, that side floats up, and now the air is trapped on one side and you are crooked. I found it a pain to deal with it. That isn't really instability, it is actually stability in a non-symmetric configuration.