BP&W trim issue

[SpyrosDives]

Hi All,

I've been diving with a backplate & wing and having some trouble keeping good horizontal trim. My setup is as follows:
Aluminium backplate (around 700gram weight)
25lb wing (the ones sold by DGX, essentially a dive rite)
Harness & simple weight pockets
Thermocline vest (neutrally buoyant)
I use 2-3 kg of weight
Oceanic Accel fins (they are very light), 3mm booties
Alu 80 tank
Large-ish mask

With this setup, the wing has minimal/no air most of the time.

Initially, I tried placing the weight on the weight pockets. When in a horizontal position and staying still, I roll backwards (i.e. my feet sink). I have experimented with the position of my hands/legs, but no luck.

I tried placing a 2kg weight on the top tank band, and that fixed the problem. If I do that, the problem is that I have practically no ditchable weight.

Any ideas?

For reference, air consumption is fine (the limiting factor is usually NDL and time). Experience-wise, I have around 110 dives and have done up to the PADI rescue diver course. I'm a warm-water fish.

Spyros

 

[CptTightPants21]

Two options.

1. Dive with no ditchable weight. I don't. If you diving a balanced rig you will be able to swim it up from depth.

2. If you insist on ditchable weight. From your description the wing is very litely used, you could add a few extra lbs/redistribute it so that you have trim and at least 1 or 2 lbs ditchable.

 

[tbone1004]

don't worry about ditchable weight. if you can't kick up 2kg from the bottom with fins on you are not fit enough to dive. That simple. If at the surface and you have a wing failure and have to stay up there, then just ditch the whole rig

 

[Compressor]

A few questions: Where do you put the tank band near the tank neck? How far down?
Is the trim off all throughout the dive or when the tanks is full or near empty?

Thanks

 

[SpyrosDives]

A few questions: Where do you put the tank band near the tank neck? How far down?
Is the trim off all throughout the dive or when the tanks is full or near empty?

Thanks

This is a bit hard to explain. Starting for the top of the part of the tank that is straight in the longest dimension of the tank (i.e. excluding the "neck"), the top strap starts at around 2-3 inches down. I have tried moving the tank up, but then the regulator "squeezes" the wing a lot, and I also bump my head on the regulator.

Thanks for all the answers!!

 

[tbone1004]

just leave the trim weight on the cam band if it works for you. seriously, ditchable weight especially with that little of it is just not needed. I honestly can't remember the last time I dove with ditchable weight and can't think of a circumstance where when diving with a balanced rig it would be necessary

 

[RyanT]

don't worry about ditchable weight. if you can't kick up 2kg from the bottom with fins on you are not fit enough to dive. That simple. If at the surface and you have a wing failure and have to stay up there, then just ditch the whole rig

What tbone said. If you only need a small amount of weight, putting them in the cam band pouches is often a nice solution.

 

[Compressor]

This is a bit hard to explain. Starting for the top of the part of the tank that is straight in the longest dimension of the tank (i.e. excluding the "neck"), the top strap starts at around 2-3 inches down. I have tried moving the tank up, but then the regulator "squeezes" the wing a lot, and I also bump my head on the regulator.

Thanks for all the answers!!

Move tank up and down to help with the trim: Tank up towards your head ---> trim will move your body towards horizontal.
And vice versa.

Perhaps a picture of your set up will help people help you.

 

[seeker242]

I would just use the cam band pockets. Should still be easy to swim up without ditching anything.

 

[AlexL]

Starting for the top of the part of the tank that is straight in the longest dimension of the tank (i.e. excluding the "neck"), the top strap starts at around 2-3 inches down. I have tried moving the tank up, but then the regulator "squeezes" the wing a lot, and I also bump my head on the regulator.

this seems a bit odd, and i cant really picture it in my head while making sense.

with both my and the wife's BP/Ws, which are both steel, one being a freedom contour with a hollis s25 wing, the other being an OMS with STA mounted in the lowest set of holes and DGX 25lb wing, when diving single AL80s, the top cam band is right on the edge of the shoulder of the tank, which puts the top of the wing slightly below the valve opening. when mounted turret down, the mk25 barely overlaps the top of the wing, and is located near the top of the shoulder blades, barely touching the base of the skull when in trim and looking up. a fully inflated wing tends to press on the 1st stage a bit, as well as the hoses, but not significantly or to the point of concern.

so having 2~3 inchs gap between the top cam band AND having the 1st stage interfere with the top of the wing seems to indicate the wing is located higher then usual? does the rear dump valve on the wing clear the bottom of the plate? pictures of the whole assembled rig front and back would be great to see in order to understand how the components are located relative to each other.