«Damit das automatische Auslassventil richtig funktioniert, muss das Ventil richtig eingestellt sein und der Taucher sich in einer aufrechten Position befinden.»
[«For the automatic exhaust valve to function properly, the valve has to be adjusted correctly and the divers needs to be in an upright position.», my humble translation, my emphasis]Hopefully, the booklet authors intented to refer to this condition: the suit exhaust valve needs to be positioned as high as possible on the suit in order to be able to deflate the dry suit. However, that the diver needs to be in an upright position, as the SSI booklet says, is simply wrong.
Of course, I laude the authors' aim for plain, simple and comprehensible language. But they overshot their goal here, teaching things simply wrong.
Of course, many of you may follow the attitude of «who reads manuals anyway?» However, there are students that like to read things to have a second source of information beside their instructor. So let us hope that students will read manuals with a sense for wrong information and will ask their instructors.
On the backdrop of what dive training organizations with their roots in technical diving teach, this SSI explanation looks somewhat strange. Just think of why diving and hovering in horizontal position is of so much importance: the increased water resistance works as damping and thus helps in maintaining better buoyancy control in such a horizontal diving position. Also, tissue gas diffusion is more uniform over the whole body in this position compared to a vertical position (due to the large vertical pressure difference).
Thus, diving and ascending in a horizontal position is clearly preferrable. And next, dry suits are typically worn in cold conditions, where blood circulation gets limited and thus gas diffusion becomes suboptimal too. In consequence, the correct diving position becomes of even greater importance.
And now SSI claims a strong background in technical diving and at the same time trains its students in a completely contradictionary sense? SSI should know better and correct their training booklets. It is really sad that no one at SSI seems to reread their own manuals.
Cynics may note that at least divers following SSI's instructions may die upright.
Unfortunately, this issue doesn't seem to be a single, minor glitch. Instead, we see related issues also in other places. For instance, the training video for the «Deep Diver» shows really well-behaved divers: they ascend in upright, vertical position. We already discussed above the reasons why this usually is a bad idea and increases the risks to develop a DCS under some conditions. A video showing SSI deep divers first kneeling down on a sandy ground before starting the ascend in perfect clear water using a rope ... is really bizarre stuff.
