Soft hackle flies are good searching patterns. Try dead drifting them through the holes, then stripping them back in. Use some tin weights to get them down deep. Try these also in the lake from your float tube.

Hook: Mustad 339 sizes 10-18
Thread: Danvilles Fly Master in red
Tag: Gold tinsel
Body: Grey Chinchilla dubbing
Hackle: Pheasant back wrapped over, sized and pulled back