12-02-2008, 12:18 PM
Re: Sink Rates
Sink rate is measured by “inches per second” so you can count down with “Mississippi’s” to get to an approximate depth in still water. A lot of things will affect the actual sink rate including drag from current, length and thickness of leader, buoyancy of fly etc, but you can use the Mississippi’s to count down on successive casts until you hit fish or bottom, and use that to adjust you presentation. There might be some differences between manufacturers in terms of what they call them, but here's a general guideline:
Intermediate/Type I/ Slow sink = 1-2 ips good for up to about 18 feet in still water. Because of the slow sink rate, it’s good for fishing midge larva, mayfly nymphs and midge and caddis pupa that are holding at specific depth with a slow retrieve. Use 20 Mississippi increments to count down on successive casts to cover different layers until you find out where the fish are holding. The intermediate or slow sink is also great for fishing streamers over shallow sunken weed beds for bass or trout in ponds and lakes.
Fast/Type III/ Fast sink = 3-5 ips is good if you need to get down 15-25 deep in still water, and is good for fishing dropoffs along lake shores if you have them. Good for fishing buggers, dragonfly/damsel fly nymphs and streamers deeper with a quicker retrieve. Use 10 Mississippi increments to countdown.
In moving water like rivers and streams, remember that as the fly line is sinking, it is also being carried downstream, so to get the fly down you’d want a faster sink rate or you’d have to cast way upstream to give the fly time to get to depth at the target area where you think fish are holding.
Because of current, you’ll be very limited, even with fast sink lines in terms of how deep you can get in moving water. Current moves approximately 18 ips for each mph of speed, so if the main current is moving along at 3 mph and you wanted to get down 3 feet with a fast sink 5 ips line you’d have to cast roughly 30 feet upstream of the target and mend line. To see how extreme the difference is, in still water if you wanted to get down 20 feet with a 5ips sinking line you could cast out and count down about 50 Mississippi’s. If you wanted to get down 20 feet in a 3mph current with a 5 ips line, you’d have to cast 200+ feet upstream of the target (!!!) and mend like a wild man.
For fishing midges in still water, I would go with a full length slow sink on your 5 weight. If I wanted to get deep with a 5 weight in moving water, I would use a floating line and weighted or beadhead nymphs or add split shot. For your 7 weight, either full sink or floating with a fast sink tip for fishing streamers and buggers deep in lakes and in moving water. The floating line on a sink tip (as opposed to a full length sinking line) makes mending line in current easier, and I would lean towards that with a 10-15 foot 5 ips sink tip and use it to fish stuff like muddlers and other streamers up to 3' deep in current and maybe 6-7 feet deep in pools. On a 7 weight, this is a great way to catch early season stockers, decent fish behind dams if you have tailwaters, and larger browns in pools at night in summer and during their spawning runs in fall, as well as largemouth in ponds and smallmouth in streams.
Hope this helps