F4A,

That sink rate is not cumulative. If LC13 sinks at 8.75 "/sec, that is the sink rate whether it is one foot or 20 feet of the stuff. Sink rates are listed to give you an idea of a line's sinking performance, and are measured with the bare line in still water, not connected to flies, leaders, or running line of any kind. And sink rates are almost always over-stated. From my reading, anyone who does an independent test always finds that lines sink slower than their listed rate, so it's best to think of sink rate as a relative index for comparing one line to another when making your choices.

Further, you generally cannot cast, at least not worth a sh!t, by attaching a sink tip or shooting head to the end of a regular WF flyline. A shooting head is generally attached (loop to loop method) to a shooting line, either mono like Amnesia or thin floating fly line made for the purpose.

There are books that explain most of this stuff, but I don't know any specifically intended for salmon fishing. But there are steelhead fly fishing books by Trey Combs and Deke Meyer that discuss tackle in a lot of detail.

BTW, when you're adding up those grains, it might help to keep in mind that an 8 wt fly rod is rated for 210 gr, a 9 wt for 240 gr, and a 10 wt for 280 gr. 390 gr might need a 12 wt rod and still wouldn't cast comfortably. But if you attach 20' of LC13 to some mono running line, you'll be able to scrape the stones of just about any piece of water anywhere fish hold. I've never used it, and I almost never use T-14 sink tips either. For the steelhead water I fish, I normally use a 15' sink tip in type 3, 6, or 8 and add a weighted fly if I need to fish deeper.

Sg