The only SMB color that is of limited value is white - because it gets lost amidst the wave crests.
International orange and yellow are popular colors, however, you can also find bags and 'safety sausages' in red and this virulent green color.
TTBOMK, there is no 'regionally-interpreted' color. International orange does not mean one thing, and yellow another, across the entire PNW (or anywhere else for that matter).
Some individual teams, however, have set up signals amongst both team members, surface support divers and team managers, and boat captains that may be color coded - e.g. orange bag means we've been swept off the wreck by current, here is our location, we're doing drift deco, etc. whereas yellow bag means someone is either entrapped somehow or hung up; send down a safety diver with two stage bottles, etc.
But I'm not aware of any cohesive understanding, among the boat captains say from Virginia Beach down through Outer Banks, Hatteras, and Morehead City (along the east coast) that "orange bag means X while yellow bag means Y".
It's generally a more independent, team-oriented determination.
On the other hand, whereas color is of only marginal importance,
size matters.
Not sure where you're diving, and if you're diving in a quarry or smaller lake it may be less relevant, but if you're 30-70 miles offshore in the open ocean - you need to be seen. Aircraft are flying at, depending on the size and type of aircraft, between 140 to several hundred miles an hour. They fly in patterns. They fly at altitude. The pilot is sweeping his vision looking for a diver in the water. Know how small you look even from 100' to 200' off the surface of the ocean? Ever come in for a landing at an airport over a body of water and glance down - notice the glare off the surface of the sea?
So...you want the biggest frickin' tube you can possibly find if you're diving 30 or more miles offshore in the open ocean. Something like the super big one here:
http://www.halcyon.net/mc/dam.shtml
You also want a mirror to signal the aircraft - not the back of a CD. You need to be able to aim the flashes at the aircraft as its flying - military signalling mirrors have a crosshair device that lets you do this. CDs don't. They cost less than $10. You also want a strobe in your pocket in case the search goes into the night. At night a bright strobe can be seen for miles from the air out of the darkness of the ocean.
Here's one site to peruse (there are many others):
http://www.tabula-international.com/DIV/SMB3.html
As of last night there were two divers floating in the open ocean waiting to be found, one off Florida and one off North Carolina, who were both swept away by ripping currents. They aren't the first ones this season.
A mirror slips inside the cover of your wetnotes, its real handy and there is no excuse not to have one. Its going to be priceless if you need to signal search aircraft. Put a small stainless steel boltsnap on it to snap to your secondary bungee around your neck. After floating around for 6-12 hours or so your fingers might be a bit shaky, and you wouldn't want to drop the thing when you finally spot the plane.
Dive safe,
Doc
FWIW. YMMV.
