Re: Ballast Bladders

[Rick Lucertini <empiricus@sprint.ca>]

Martin Sanderse wrote:

> Is anyone using soft external ballast bladders for emergency ascent or surface
> freeboard?

Hi, Martin and All . . . I'm pasting in one of my responses from an earlier post:


"Well, freeboard was brought up as a possible downer (pun intended).  Entering or exiting the
hard-shell in waves could be tricky.  In chatting with Frank White of White's Diving (they manufacture

dry suits on Vancouver Island), I asked him about a horse collar that would lay almost flat while
submerged (to reduce parasitic drag) but would act as reserve buoyancy to increase freeboard for
surface activity during ingress or egress of the suit.  No problem.  He suggested a stretchy fabric
that would follow the shape of the bladder while inflated.  Then, while collapsed it would force the
bladder up against the skin of the shell for minimal drag.  It wouldn't be quite as hydrodynamic as
built in saddle tanks, but, you wouldn't be hauling around all that extra water mass from flooded
tanks, either.  Ultimately, the saddle tanks may win out for the simple reason that they are virtually

maintenance free and sleeker U/W.  But, quicker response would be the positive out of having a
floatation collar.  The elimination of reserve tank volume (and, hence, tankage mass) may or may not
be outweighed by the use of a draggy collar.  Priorities."


> [snip]    Unfortunately, there are some other problems,like containment of the inflated bladder,
> possible bursting as you ascend, volume of blowing air, reliability etc.
>
> Any comments?

See above.

I'll reiterate that it's my personal preference that bladders and ambient tanks only be used for
freeboard and not ascents.  Courtesy of Boyle's Law.  Dropping hard ballast incrementally is much more
controlled than rapidly expanding volumes of air dramatically increasing your rate of ascent BY THE
SECOND.  Use the KISS Principle (Keep It Safe and Simple).

IMHO, blowing ballast at depth is gross overkill and is a recipe for suicide.  I've done it scuba
diving in a dry suit.  It ain't fun.  Talk about a Trident missile.  No embolism, thank goodness.

--
Rick Lucertini
empiricus@sprint.ca
(Vancouver, Canada)

"I resent that - I don't deny it, I just resent it!"
  --- Groucho Marx ---