Buccaneer:That was my next question: Where do DIR guys keep the compass. I didn't think a retractable compass was DIR. I assume a bottom timer on one wrist and a compass on another? Wrist slate on left arm above .
The DIR system advocates wrist mounted gauges so as to maximize streamlining, minimize the risk of entanglement and keep the gauges where you can easily see them while in a horizontal position. Since your arms are out in front of you when diving in this position, mounting gauges on your wrist works well (actually, IMHO, it works well regardless of whether you are horizontal).
Right wrist = primary bottom timer.
Left wrist = backup timer and, further up the forearm, a wrist mounted compass.
I don't use a wrist slate. Instead, I carry wetnotes in a pocket.
If you are going to use a wrist slate, I suppose that it will need to go on whatever arm you don't use for writing (mine would be on my right arm).