rodrico:
Having just purchased my first dry suite, I am wondering if the urge to pee is the same in a dry suite as it is in a wetsuite when hitting cold water.
In other words, is a P valve a neccesity, or a luxury I can add later.
Spectacular Bladder control
R.
A luxury you can do without probably, for now anyway.
That is, unless you're going to push the off-gassing limits and get into much longer and colder dives.... and are opposed to the simplicity of a diaper.
Just my humble opinion.
If you set up your thermal protection to actually keep you nice and warm, especially your extremities, you'll probably have much less need to pee than you did in a wetsuit.
Diving dry, recreational depths, non-deco, with hands, feet and head well-insulated, even after 90 minutes in 40-degree water, I rarely have any bladder discomfort. I usually can follow a dive like that with a second similar dive without getting bladder discomfort. An urge, maybe, but not discomfort.
YMMV, of course, but you'll probably do
better than me with my old kidneys and bladder!
Oh, and I agree with reefugee about hydrating the day before, rather than just prior to the dive.
I'd add that hydrating gradually over several prior days is even better. That way, the kidneys won't be triggered
as much to remove the "excess" water.
If you hydrate gradually, more of that water will enter and stay longer in the blood and other body tissues.
Sudden hydration, on the other hand, causes a sudden increase in the blood volume and/or dilution of electrolytes, both of which increase the rate at which the kidneys remove water from the blood. Of course, when they remove water from the blood, they create urine which fills the bladder, which gets inconvenient.
Also, if you keep yourself real warm, especially your extremities, the kidneys won't be stimulated as much to remove water from the body.
The increased urine production, from being cold, like in a wetsuit, is a real phenomenon caused mostly by peripheral vasoconstriction and increased blood pressure, if I remember correctly.
At some point, if you're really pushing the limits of off-gassing, you might be inclined see how much additional hydration
just prior to the dive is managable for various situations and conditions.
That's when you might consider a pee valve.
Otherwise, for routine recreational drysuit diving, I wouldn't bother.
Dave C