I read an article a while back about different knots with regards to strength and purpose. This type of open looped knot was recommended for a few reasons. When nymphing this knot would allow for a more fluid drift and perhaps promote twitching? Also the application for dry fly fishing is that with smaller flies it would allow the fly to turn and swirl more freely while on the surface of the water. I have no experience with this knot. Here in a minute I will be practicing on a good 4ft. section of 6-7x tippet. Hopefully this knot will serve me well. I probably wouldn’t use it on a streamer or bigger hopper pattern but for smaller nymphs and dries I want to give this a whirl. 

• Duncan Knot Full Instructions