"Butt heavy" Rebreather Trim- stupid suggestion?

Ben Field

Okay, this is a random thought thats crossed my mind...please comment/laugh as necessary.

Many rebreathers seem to be heavier at the bottom resulting in the butt heavy trim and back pain to which divers normally counter by adding weight at the top.

However many of the Rebreather divers I've met have more than enough ballast anyway so this additional lead is otherwise uneccesary.

If this is the case- Why not make the bottom end of the rebreather lighter/more buoyant instead?
(Obviously it doesn't need to "float" but it could shift the trim centre higher up the unit.)

I'm imagining either a foam block or the kind of buoyancy tubes heavy camera housings use for trim... perhaps even an adjustable trim tank!

Ok, enough of the crazy talk.... obviously this is only relavent if-
A, You have a rebreather that suffers this issue.
B, You don't need lots of lead to achieve negative buoyancy already
C, A small amount of additional buoyancy would not be dangerous.

If you can say Yes to all three what do you think of the idea?

regards,
"Crazy/Not had enough sleep" BEN

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Beware Fridge Suck

decoweenie

Already done...

I have used the (clear) OMS emergency tube to adjust trim in the past. However, just bought some really-nice (black ) Gates positive trim tubes for their cameras.

Of course, in the Summer here, I dive with skin or 3mm when shallow so don't want to lift extra trim weight unneccessary as the rig is already enough to sink.

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"...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..."

- Rebreather World PM

rogeringebo

Try to dive with valves/1st stages up.
Makes a huge differens for me....
I also changed from Jetfins to OMS Slipstream fins...look the same and feel the same but are neutrally boyant.
Good luck!
Rodge

decoweenie

I do that for the KISS units, but not enough room with the APD-style straight-valve for the Meg or TF.

And I have too many of tanks with APD valve to change them all.

The best thing about the Meg is its natural trim tendency is very nice even with the tanks down.

__________________
"...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..."

- Rebreather World PM

nigelh

<sigh>
Oh to have a problem like that...

Always diving dry, and being averse to the cold, in the UK I have lots of lead so the seperate suit inflate bottle, the old lead acid torch and steel bailout stages earn their keep. I still have spare for 2.7Kgs in the Inspiration top pocket and another 2Kg shot bag thrown on top of the scrubber to trim level so stops are motionless. (I hate chasing buddies who fin on stops.)

I confess I resent the lead. It doesn't seem to be paying for its passage so to speak. It was the one thing that disapointed me switching to the CCR from a 300bar twinset. Going back to all that lead.

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nigelh

decoweenie

... but you don't have to lug all the dive gear in 40-50C sun either...

In the dead-Summer, the water is so warm that if you turn your back while the boat is moving and got splashed, you would have thought someone just pe*d on your back...

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"...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..."

- Rebreather World PM

trob09

I'm curious to know how you would know what that feels like...on second thought, I don't want to know.

decoweenie

There was this one time in Bangkok...

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"...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..."

- Rebreather World PM

CharlieT

Listen, if you want to be banned, you'll have to be bolder than this

I know you secretly envy DrMike

Charlie

onetime

Just to be clear, I've never been to Bangkok.