Re: The " build a sub for under $500" plans rip off

[Rick Lucertini <empiricus@sprint.ca>]

Ben Trumble wrote:

> [snip]      It is, I should note however, a viable semi-dry sub.    [snip]    Better
> semi-dry designs are always open at the bottom of the boat.    [snip]
> I tried using it in the semi-dry sub I built in Honduras 12 years ago and I
> had nothing but problems.  Bouyancy really needs to be maintained
> automatically.

Hi, Ben & All . . .

You just concurred with a point that spills over into ambient tanks being used for buoyancy off the
bottom. (yes, Pop, Mech., Jun'70 - um, I think) Automatically, in Markham's case, meant a pipe
overflow from expanding air in the cockpit.  A healthy diameter on the pipe would allow for safe
expansion.  Sufficient compensation while diving is another matter.  He was using a regulator that I
doubt would provide sufficient airflow into the bell.

This system is an overgrown diver's compensator: we all have to be attentive for the entire dive
trying to keep our buoyancy as neutral as possible.  It certainly is distracting from actually
enjoying the dive.  In your case, the same thing seems to apply.

In terms of Markham's hatch (if it's the same boat we're referring to), it was on the side of the
hull.  His canopy was permanently mounted on the hull.

Overcoming this buoyancy problem - in an ambient sub - is simple: make it a very low volume dry
cockpit with an automated pressure compensating system.  No more bubbles and a lot more comfortable.
No popping out for a look around, tho'.  I like ambient because of the viewing areea that's possible.
Little risk of implosion, too.  Splat.

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

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