Correction on the above, the fish were primarily traveling east to west. The boat I was on was traveling west to east. We drifted for miles seeing pods approaching.
Because we would often get 'jammed' by fish coming right at us, the technique required the ability to spot the pod way in advance and 'set up' the fly in a particular strike zone similar to sight fishing steelhead that are not really interested in chasing anything.
So if we saw a pod at 11 o'clock, I would cast to 8 o'clock and throw a big mend as the boat drifted forward at the approaching school. Even still if the line had not gone beneath their column the first few would scurry off to the sides but I would leave it on it's approach and twitch it as more followed suit and watch the trailing fish pick up the fly with a flash.
Pods were also to the sides, especially the shallow side, where they could be seen 'grubbing' erratically in no particular direction. These fish were gimme's, almost guaranteed to hit the fly if it was in their down-turned attention span.
The majority were in deeper water, avg 5-6ft in our case. There was no chase in them in an upward vector, period. This made it tough. The first few of the pod would veer away if they saw the descent of the fly, in particular the dark sinking head. Intermediate lines would work but only if you had a set-up distance long enough to get it beneath the fish. This was not practical so I settled for turning off the leading fish of the pod to pick up the middle and trailing fish, which would greedily gobble up the deep eel if it was beneath their column of travel.
Lances tied with subtle colors worked best. These had no angel hair, traces of chartreuse, and rootbeer-pearl flashabou blended underneath the ultrahair.
Occasionally you would be able to set the cast so that the lead fish would only see the fly below them and take it. With some wind riffle on the water that was the exception rather than the norm. I was able to target and land some lone singles when our position and the fish's approach allowed it. Multiple legals up to 33" but most were 24"-28", I only recall a couple of smaller fish. In the bright sunshine of mid-day, can't beat it. Only one was not sighted.
We spotted some submarines during the course of the day. I lost a couple that were deep in my backing. We fished about 3-4 hours total. We called it a day when you could no longer spot them easily, although you could blind cast for them in various locations closer to shore late in the flood.
Bob, I am not saying I could even catch a micro in the conditions you had but only mean to convey that we had a banner day by ensuring that the visual contact point between the fish and the fly was always in their downward cone of vision. All other presentations did not produce.
Great topic!