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  • Writer's picturePaul

Scientific Anglers SONAR Leader Review

Updated: Nov 4, 2021


Ever been on the water with only a floating line but wished you had a sink tip? I sure have! A floating line undoubtedly works well in many scenarios, but there are times when getting your fly down just a bit deeper is necessary. Not only is buying and rigging a spare spool costly, it's just another thing to tote along that adds bulk to your bag, pack, or vest. Is there another simpler option? YES!

The new Scientific Anglers SONAR Sinking Leaders are the perfect answer. These 10-foot leaders quickly attach to the end of your fly line with a loop, which basically converts your floating line into a short sink tip. Although there is one floating model in the mix, the other four varieties all sink; there's a pale green Hover (1ips), light blue Intermediate (1.5ips), dark green Sink 3 (3ips), and a charcoal Sink 6 (6ips).

Length: 10 feet

Grains: 50

Tapered: Yes

Core: 25-pound Monofilament

Sizes: 5

Price: $14.95

Each line is built on a 25-pound mono core and features a taper that starts out thick like a standard fly line, but ends with basically a short piece of the bare mono core (roughly 1 to 1 1/2 feet long or so) to tie a leader/tippet to. The thicker end has a welded loop for easy attachment to the main fly line. All leaders weigh-in at 50-grains.

At the IFTD show this year, Scientific Anglers' Brad Befus took some time to walk me through all of the new products, including the SONAR leaders. I was able to grab two for testing: an Intermediate and Sink 3. My two test leaders boast very smooth butt and mid sections, while the short mono tip portions have a slight amount of texture to them. Both leaders are nice and supple along their entire lengths. Also of note, each leader has the identification/sink rate clearly marked on the butt section—VERY handy!


Casting these leaders was a piece of cake. There's obviously a little extra weight to be felt during the cast, but it was easy to keep my loops tight and smooth. The only little difference when casting or manipulating the line is that the loop-to-loop connection between the fly line and leader obviously does not flow through the guides as seamlessly as a standard one-piece sink tip line would. With that said, this connection is low-profile enough that it never gave me any huge difficulties on the rods I fished. On rods with larger snake guides, it's even less noticeable.

Besides fishing, I first tested both leaders in a swimming pool so I could easily observe how each would act in the water. The leaders got down without any bad bowing or hinging, but both looked a little wavy/crinkled as they sank. However, giving them a good stretch before use did seem to help with the memory somewhat. Of course, when under light tension during stripping, the leaders came through the water nice and straight.


SONAR Leaders are incredibly handy and very affordable. As someone who likes to pack light and doesn't use sink tips a ton, these will surely be an important part of my arsenal for those times when I might need to get the fly down a few extra feet. While maybe not quite as nice as a true sink-tip fly line, in a pinch these offer a quick and effective alternative.

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#LineAndGear #ScientificAnglers #FlyLines #Leaders

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