WHEN YOU GET RIGHT DOWN TO IT, delayed surface marker buoys are there for two reasons. First, they give you a personal ascent-line that you can deploy at any time, which means that wherever and whenever you surface you’ll still have a visual reference to help control your ascent-rate and hold stop-depths.
Second, your blob popping to the surface shows people where you are, which means a quicker pick-up by the boat, and limits the chances of you being missed and left drifting on an empty sea.
Kit-wise, all you need is a buoy, available in many colours and sizes and with various options for inflation; a length of line suitable for the depth in which you’re diving; and some sort of reel to keep the line neat and tidy when you’re not using it, and allow the line to unreel smoothly and under control when you come to send up the blob.
The simplest reels are finger-spools, and they’re my preference for a DSMB. They’re small, lightweight, and with no moving parts they pretty much last forever.
The line is tied to the centre spindle of the reel and then wound around the reel until you get to the end, where you use one end of a double-ended bolt-snap to hold the line securely in place, and the other end to attach the reel to a convenient D-ring.
Remove the clip to free the line, attach to the buoy if necessary, then inflate the blob and away it goes. As you ascend, wind the line around the spool and use the bolt-snap to secure the line to the reel at stop depths. Simple. Sea&Sea sent me its latest IST finger-spool to try, and it’s a cracking piece of kit.