Hi,

Beaverkill54 makes some good points! Were the flies sinking right away (first cast) or were they just eventually getting waterlogged and sinking? Was the water broken, riffles, or a smooth glide? Since I don't have any CDC flies, I'm not sure how they react in such conditions, but rough water can drown any dry fly. Riffles and such can also break the surface tension, making it difficult for a fly to stay suspended in the surface film.

Presentation can make a difference too. For example, if the presentation causes the fly to smash down on the water surface, it may just be getting forced under. I know I have to sometimes remember to ease back and delicately drop the fly rather than just smash it down.

- Jeff

P.S. I swear when I wrote this your post on testing them in the sink wasn't there!