Tying issue with streamers

Hello again gang,

I have been tying flies for quite a while and only just recently
started tying them for sale in our shop. I have fished with TONS of
tied flies from our tyers and seem to be having a problem I hope this
group can help me solve.

My tandem streamers fish great, and work perfectly, in fact I have had
many compliments from old, weathered fishermen on them which is
always nice. The problem I am having exactly is that some of my single
hook streamers tend to roll over when fished. It seems that hydro
dynamics and aerodynamics should work about the same, but in practice
maybe not. It seems to me a streamer wing would naturally keep a fly
upright when tied on top. Some flies work great and some don't at all.
I don't want to be selling flies that roll belly up when fished.

What exactly is it that makes a streamer that looks well tied, roll
upside down when fished?

I have copied the patterns of my tyers to the letter, and still seem
to occasionally have this problem. The ones I have the hardest time
with are patterns with multiple hackles on the wings. Grey ghosts and
the like in particular. Patterns with only one or two hackles seem to
stay upright. Are the feathers out-weighing the hook? Even if this is
true why wont they right themselves when stripped in? Any help would
be appreciated.

Lloyd Metcalf
The Fishin' Hole
http://www.mainetackle.com