What does "delayed" refer to in SMB?

[AbyssalPlains]

I've always wondered why a surface marker buoy is called "delayed"? Mine is never late-quite the opposite, usually it breaks the surface before I do.

???

 

[String]

Surface Marker Buoy - a larger inflated bag, usually ball shaped, sometimes with a dive flag on top that's inflated prior to the dive and towed for the entire dive.

Delayed - rolled up small bag that's inflated under water usually at the end of a dive and sent to the surface via a spool or reel and then towed by the dive.

We use a delayed here on 99% of all our sea dives.

Edit:

A normal SMB (on the right) which is inflated prior to a dive and towed the entire dive. Used if you expect very strong currents or are shallow in a high boating area.

DSMB sent up from depth. Different shape and used at the end of the dive so the boat can see you.

 

[Charlie99]

It's "delayed" compared to a flag that you pull throughout the dive.

 

[djanni]

A DSMB is designed to always be tied to a line and deployed from depth, while an SMB may be deployed from the surface only.

 

[ruready7]

I learned something again from this site. Keep them coming.