Re: DEEP and FAST nymph rigs?
That sounds like a bad situation. Sometimes it is best to just come back another day. Here is what I would do. You need some heavy weight to sink quickly and a good indicator. I would start with a couple of BB or even 3/0 split shot. Your fly should also be weighted. When using a lot of shot on a nymph setup I loop the tippet onto the end of the leader. I put the shot on the loop just above the knot. This keeps the shot from sliding down toward the fly. If you are using a leader with no knot on the tippet you can wrap the leader around the shot before you crimp it. That is: you lay the leader into the open slot and then wrap the leader around the shot once before you crimp it. The wrap-around will keep the shot from sliding down the leader. You need to cast up and across the currant using a reach cast. The further up stream you cast the quicker and deeper it will sink. If you cast too far up stream the fly and shot will be washed onto the bottom and you will get hung up. After you have figured out how far up stream to cast you adjust your position so the fly is sinking and covering the water you want to fish. You will have to mend the line as it passes your position. The reach cast will give you a good mend to start with.
The other approach is with a sink tip line but it will have to be a rocket line to get it down quickly. I have found that I prefer slower water to fish a sink tip line. One problem with a sink tip line in fast water is you have a lot of fly line in the water and it is hard to tell what your fly is doing.