halocline
Contributor
Steel plates are typically 5-6 lbs and offer about that much in ballast. AL plates are closer to 2lbs and offer maybe 1lb in ballast. Al plates are a little easier for travel, maybe 4lbs lighter. Keep in mind that a steel BP/W with a small wing and webbing harness typically weighs about as much as an average jacket BC, and is less bulky for travel. The scubapro classic, as an example, weighs over 10 lbs and is probably about 2-3lbs positive in the water.
A general rule of thumb for warm water is to use a steel plate with an AL tank and vice-versa, although it does vary from person to person. You can simulate the ballast of a steel plate when using an AL plate by putting 4-6lbs of weight on the cambands. They make nice little pockets for that, or you thread the weight right on the camband. If you're diving in a 3 mil shorty, single tank, and you're not overweighted, you don't need any ditchable weight. It's only when there's a potential for you to be very negative at depth (or on the surface) that ditchable weight is a real safety factor. Offsetting the ability to purposely ditch weight is the possibility of accidentally losing it at depth and having an uncontrolled ascent. So there's two sides to that issue.
If you're using steel tanks at home and planning on renting them in Coz, probably an AL plate makes the most sense for you. Many of us who have switched to BP/W set ups end up with both a steel and AL plate eventually. The plate and webbing are not very expensive, and you just put the wing on whatever plate you're using at that time.
Occasionally I have to drag my old jacket BC out of the closet and use it for demonstrating skills in OW classes. Whenever that happens, I end up "pistoffo'ed" at how crappy it is to dive with jacket BCs.
---------- Post added October 18th, 2013 at 11:48 AM ----------
Exactly, except it's only like trying on a new coat if you're planning on wearing the coat underwater!
