Quote Originally Posted by Ray Kunz View Post
Just adding a different viewpoint to what Buddy Sanders has said we might want to consider why the hook eyes were turned up, straight or turned down in the first place. I do not claim to be an expert here but history seems to indicate that turned-down and turned-up eyes addressed tying a gut snell to the hook shank with the snell being carried straight forward through the eye. Even earlier, hooks had no eyes where the gut was lashed directly to the hook shank.
With the development of plastic for tippets in the mid 1900s the bent eyes were not neede any more. My discussion with a hook manufacturer several years ago confirmed this and it was added that the up and down bent eyes were only continued because fly tiers and users traditionally expected them.
Many tiers find tying with straight eye hooks makes it easier to finish off a fly head. (including trimming Muddlers)
Straight and turned -up eyes on very small hooks were preferred because they did not further reduce the small hook gap.
You're (mostly) correct. It wasn't so much the gut snell -- you could do that with an eyeless hook -- but the preferred knot in the gut era was the turle knot, which passes through the eye and the knot is on the hook shank. Unfortunately, the turle knot doesn't hold very well with nylon leaders (and I suppose it's even worse with fluoro-carbon) so it isn't used any more. We use TDE and TUE hooks for the same reason we still measure tippet size in "X" designation -- it's a holdover from gut.