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"Mr I.M. Horsfall" <imh@li*.ac*.uk*> wrote:-

> ... If you have not used it in a while it will remind you to take a
> refresher course. ...

If you haven't used it for a while because you've been using an aqualung for a
while, then you've kept in practise in diving although not with that
particular set. Ditto ifyou've been away and you've used a rebreather
belonging to the place where you've been diving. How do you tell the set's
computer that?

> 3 We did not see a Mk5 so we can't comment directly on how hydrodynamic
> it is. My impression is that it will be more streamlined than a twin set.

As I said before, Peter Readey found that the Carmellan SMS2000 backpack box
set's abruptly square back end caused severe hydrodynamic drag in forward
swimming. E.g., if a set is listed as 6-hour duration, that is really only 4
hours if he swims a lot rather than working in one place and a third of the
oxygen used is used in extra work to counteract extra hydrodynamic set drag.

> 4 Buddy breathing with the closed circuit mouthpiece would be next to
> impossible in an emergency. Ingress of water could be minimized by switching
> the mouthpiece to OC whilst the mouthpiece is moved between divers. ...

Why not a second CLOSED-circuit mouthpiece running off the same circuit?

Re a loose mouthpiece with a rebreather: aqualung divers get very casual about
keeping the mouthpiece seal tight, for a little water getting in doesn't
matter; and most rebreather divers soon to come will likely be already
aqualung experienced. In industrial oxygen rebreathers for use on land, the
experience of most of this century has taught their makers to put in the
mouthpiece an extra flap that goes outside the lips and has on it neck straps
to strap the mouthpiece in and keep the airtight seal. And many of them, amd
many naval rebreathers that I have seen, have fullface masks.

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