2.. If there is no surface activity would I be better off fishing an clear intermediate line? (we call them slime lines in the UK)
Tom: If there is no surface activity you might try fishing with a sinking fly first. A leader composed of Rio's Flouroflex Fluorocarbon material will help the fly to sink quickly. The clear lines may help with spooky fish if that is a problem. If you have to get down fast in current, try a fast sinking line with a short leader and a lead eyed fly.
Cathy & Barry: We use the intermediate lines in any wave situation whether there is surface activity or not. On calm surfaces when fish are feeding on the surface we prefer a floating line. Otherwise, we stick with the "slime" lines.
Brad: I think that using a sinking line when there is no surface activity is a good idea, and it is one that I do myself. Note that this is still not a solution to the big wave problem, but it will put your fly down deeper and let you get to fish on the bottom. One other matter does need to be addressed. We are talking a lot about fishing blind here. This is something that I like to avoid whenever I can. The most productive way to fish is to spot the fish and then make your presentation. The reason for this is simple. You get to watch the fish do everything. The fish reacts to your presentation, pattern selection, and any action that you impart. The fish then eats the fly while you watch him do so, if there is a better way to know when to set the hook, I do not know about it. This is THE best method for fishing in the salt...or anywhere. All of the big fish that I have ever caught were spotted by me before I ever made my first cast to them.
Gazza-baby: Very often, especially in the conditions mentioned above there is little surface activity to be seen. This does not mean the fish are not there and certainly does not mean they are not feeding. In these circumstances a slime line would definitely be worth trying. Its almost like fishing a river or reservoir, if the fish are not taking dries off the surface you go down deeper with nymphs and then deeper again until you find them - It's exactly the same in the salt.
Bruce: All depends........, if the water is quite shallow, then it is probably better to stay with a floater. If it is deeper and the target fish is not one that commonly feeds on the surface then an intermediate (or faster) sinking line would probably be better. The nice thing about the clear lines is that they are less likely to spook fish. If you are blind casting that can be a big plus. If your anticipated prey is an active surface feeder you can often lure them from considerable depths with a floating line and a noisy popper.
Sight-fishing, at least up to now, has been impossible. If I was seeing fish, or surface activity, then I'm fairly sure that I would have caught fish. I haven't been anywhere that offers "flat's style fishing"... yet. It seems therefore that my first approach should be either with the slime line (or faster) or with a surface popper. Having been given this advice, my mind said something like "of course!" - this is exactly how I tackle trout; I either get the fly down to within 6 inches of their heads, or else I fish a big dry fly or twiched muddler (It's nice to find parallels between trout fishing and saltwater fly - this is in fact exactly the sort of thing I am after).