I was fascinated by a recent fly fishing forum thread that warned of the dire consequences of using full sink lines for streamer fishing in rivers. What perdition awaited those who had the temerity to throw the heavy, thin line?

Hard to cast.

Always getting snagged on the bottom.

It was like re-imagining the opening of “The Right Stuff” with a fly fishing bent. “There was a demon who lived in the water…” But, that’s a movie for another day.

Nonetheless, I found it disappointing on a number of levels, among them: sinking lines are only hard to cast if you do it wrong; I don’t get hung up on the bottom any more with a full sink line line than I do with a nymph rig (probably less); internet forums can be a minefield when it comes to getting good advice.

Most of all, when you’re asking the question, “What do I want the fly to do?” sometimes a full sink line is a critical part of that answer. Here are a few quick tips to help you navigate the waters with a full sink line on your next streamer outing. For our purposes, I’m using a Teeny T-Series Integrated Line, and I’m fishing in a river.

One good false cast, and boom, out she goes. As Dr. Strangelove asserted, “It would not be difficult!”

Casting. The key to casting a full sink integrated line is to get the full sink part out of the water. I strip line in (whether I’m using a strip presentation or not) so the head is at the rod tip. A roll cast to get the line out, a backcast to aerialize the line, then bombs away. Maybe a couple false casts. Because of their head weight and thin diameter, I find full sink lines fairly easy to cast. You’ll want to use a shooting basket for the running line. And of course, match the grain weight of the line to your rod and casting style.

Snags (or not). Every day is different, but the last time I used my full sink line on the Farmington River I didn’t get terminally stuck on the bottom once — and I was using a weighted fly. Current speed, depth, mending, retrieve speed, sink rate of the line, fly profile and weight — all are factors. The lower and slower the water, the greater your chances are of getting stuck. So pick and choose your water and conditions. Pools and runs with submerged logs, branches, sharp-edged rocks, and boulder fields are often bad places to throw the full sink. If you do get stuck, try this trick: don’t try to horse the fly out. Come taut to the fly, then do a few roll casts. Often that’s enough to free the fly. Finally, if you’re trying to present along the bottom — as with nymphing — touching the bottom is part of the price of admission. The false positive of a snag is confirmation that you’re getting deep. And remember to check those hook points. Sticky sharp!

What do you want the fly to do? This is the million-dollar question that many anglers never consider — but should. I’ll pull out the full sink integrated line for streamer fishing when:

• It’s summertime and the river has come up and is off color, and I want to get a neutral buoyancy effect from the heavy line (consider it split shot) and a deer hair head fly. (Leader length would probably be around 7 feet.)
• The water is cold and I suspect the the fish are holding close to the bottom. (Shorter leader, usually no more than 3 feet.) Check out this streamer leader diagram.
• I want to get the fly, even if it’s weighted, to sink as quickly as possible. This usually indicates a very deep hole as the target zone. Again, shorter leader.

High late summer water, full sink line (weight) + Zoo Cougar (wants to float) = neutral buoyancy. Oh. And this trophy trout, too.

I hope that helps, and as always, if you have questions I’m happy to answer them.