BP/W configuration question

[jimbeeler]

OK all you BP/W gurus... I've been using a regular back inflate BCD and have also been using a Transpac. This winter I decided to piece together a Stainless Steel Plate/Wing configuration. I wanted to go with a SS Plate so I could reduce weights when diving in Salt Water. The plate weighs about 5 1/2 lbs. I'd also prefer to dive with the same configuration in both Salt and Fresh water. I only dive wet and pretty much in warm water.

I took it out yesterday and played around with it in the local quarry. I was wearing a 3/2 full. I found that I did not need any weight to be neutrally buoyant with no air in the wing and 500 lbs in the tank.


Here's my problem:

I found that despite the BP/W being snug and not moving on my body, I felt really "tippy". That is, I felt that I was going to tip over on my back (kinda turtle up). It didn't happen but I felt very unstable. Not really sure why unless the fact I wasn't carrying any weight and the wing was empty could have accounted for it. Kinda like a ship with ballast in the hull keeps it stable.

If that's the case, should I stick with my Transpac or an Aluminum plate for fresh water so I'll have to add a little weight and use the SS plate for Salt Water?

Thoughts?

Jim

 

[victorzamora]

Did you feel tippy at the surface or during the dive?

 

[jimbeeler]

Did you feel tippy at the surface or during the dive?

During the dive... Neutrally buoyant and level.

Jim

 

[NAM001]

Until you can further fix the problem try putting on a couple of # of weight so that the wing will lift the tank and keep it on top. My GF had that problem we went to a al plate and put on 4#. all was well.

 

[jimbeeler]

Until you can further fix the problem try putting on a couple of # of weight so that the wing will lift the tank and keep it on top. My GF had that problem we went to a al plate and put on 4#. all was well.

That's what I was thinking... I do have a Aluminum Plate I can try. I was just wondering if the "tippy" feeling might originate from all of the weight being on the backplate and the buoyant part, me and the wetsuit being below the weight. I was thinking that if the a lighter plate and adding a few pounds on a weight belt, it would fix the problem. It seems logical but didn't know for sure.

Jim

 

[victorzamora]

It couldn't hurt to try if you have all the required pieces. However, I've done dives similarly set up with no tippiness.

 

[jimbeeler]

It couldn't hurt to try if you have all the required pieces. However, I've done dives similarly set up with no tippiness.

So you've been diving with no weights, a SS backplate and no air in the wing?

Maybe it's just me getting used to a different feeling configuration.

Jim

 

[cool_hardware52]

OK all you BP/W gurus... I've been using a regular back inflate BCD and have also been using a Transpac. This winter I decided to piece together a Stainless Steel Plate/Wing configuration. I wanted to go with a SS Plate so I could reduce weights when diving in Salt Water. The plate weighs about 5 1/2 lbs. I'd also prefer to dive with the same configuration in both Salt and Fresh water. I only dive wet and pretty much in warm water.

I took it out yesterday and played around with it in the local quarry. I was wearing a 3/2 full. I found that I did not need any weight to be neutrally buoyant with no air in the wing and 500 lbs in the tank.


Here's my problem:

I found that despite the BP/W being snug and not moving on my body, I felt really "tippy". That is, I felt that I was going to tip over on my back (kinda turtle up). It didn't happen but I felt very unstable. Not really sure why unless the fact I wasn't carrying any weight and the wing was empty could have accounted for it. Kinda like a ship with ballast in the hull keeps it stable.

If that's the case, should I stick with my Transpac or an Aluminum plate for fresh water so I'll have to add a little weight and use the SS plate for Salt Water?

Thoughts?

Jim

Jim, the idea that one can fully relax in the "prone" diving position and not be subject to a rolling moment is just not the case. I like to keep the tank close to my back by using a flatter plate and no STA, but that's only part of the solution.

The ket is is the position of your fins and legs.

If you are horizontal, with with your knees bent and your fin blades horizontal spread your knees apart so your fin blades are ~ 4 -5 feet apart. The flat surface of your fins 4-5 feet apart is quite effective in countering the rolling moment.

Try it with your fins / knees together and again with your fins wide apart. I think you will find that increasing the "arm" through which the over turning moment is applied will help a great deal.

Look at the pics of tech divers hovering motionless. None have their fins close together.

Tobin

 

[jimbeeler]

Jim, the idea that one can fully relax in the "prone" diving position and not be subject to a rolling moment is just not the case. I like to keep the tank close to my back by using a flatter plate and no STA, but that's only part of the solution.

The ket is is the position of your fins and legs.

If you are horizontal, with with your knees bent and your fin blades horizontal spread your knees apart so your fin blades are ~ 4 -5 feet apart. The flat surface of your fins 4-5 feet apart is quite effective in countering the rolling moment.

Try it with your fins / knees together and again with your fins wide apart. I think you will find that increasing the "arm" through which the over turning moment is applied will help a great deal.

Look at the pics of tech divers hovering motionless. None have their fins close together.

Tobin

Good info to think about. To be honest, I'm not sure whether my knees were separated or not. I was frog kicking so I'd assume they were. I'm not using a STA (the plate has it built in). It's tight against my back and the tank tight to the plate and I'm using a crotch strap.

Don't get me wrong, I don't think I was going to flip over but just had a tippy, unstable feeling that I'd not experienced before. The only thing I could attribute it to was the fact that I had all of my weight in the plate. And I obviously had no ditchable weight. I really wasn't sure of the physics and whether a better choice for me (at least in fresh water) was an aluminum plate and adding a few pounds of lead on my belt. I didn't know if that would add a certain measure of stability to my body. Or maybe it's just getting used to it (like the first time you paddle a kayak).

Jim

 

[eelnoraa]

You are just not used it yet. Give a few more dives. You will learn how to balanced to out in no time