As a “novice” fly fisherman, I just ran across a new concept for me concerning sinking tip lines. I was considering a 10wt. rod purchase for steelhead, salmon (or other big guys) and thought a sinking tip would be useful. While shopping for fly line, instead of seeing fly line for a 10wt., I saw “grains”. How does this equate to a particular weight rod??
10wt for Erie steel? Overkill.
Sink tip for PA Erie tribs? Overkill.
That is, of course, assuming you’re using it around home.
Grains are a measure of weight or mass just like ounce (1 ounce = 437.5 grains) or grams (1 gram = 15.4323584 grains). Because grains are a smaller measure of weight, fly line is rated in grains for the first 30 feet of line. This is the AFTMA rating of fly lines that rod makers use to rate their rods. Basspro has a pretty good explanation which shows the AFTMA scale for fly lines. For your 10 wt rod, you need a line that is 280 grains +/- 10 grains.
Grains has nothing to do with whether the line floats or sinks. That depends on density or specific gravity. Fly line of the same weight can either be designed to float or sink and the rate at which the line sinks depends on how dense the fly line is, i.e., the mass per diameter of the line.
Sinking fly lines are rated as to “Type” from 1 to 6, with the higher number sinking faster. Type 1 fly lines sink at 1 -2 inches per second, Type 2 at 2-3 IPS, and so on. I use the rule of thumb that a type 1 sinks 1 foot per 10 seconds, a type 2 at 2 ft per 10 seconds up to a type 6 which sinks at about 6 ft every 10 seconds. This is an approximation but it is easier to apply than the inches per second rule.
You need to buy line that your fly rod is rated for and within that line rating, buy the density of line that will give you the sink rate you want. What is important is not the grains (weight) but the sink rate (density). Some manufacturers such as Teeny rate lines in grains but to me that just confuses people. For those manufactures, look for sink rates.
You might want to read the following sites for more information:
http://www.byrdultrafly.com/sublines.htm
http://americanangler.com/index.php?option=com_content&task=view&id=361&Itemid=87
BTW, thanks Whatfly for correcting my original post. I have made the corrections above.
Manufacturers of lines rated in grains will usually recommend a range of rods the line should work well with. For instance manufacturer may say their 250grain line will work well with 7 to 9 wt rods.
But a 7wt line is rated nominally for 185 grains for the first 30ft. So isn’t 250grain line too heavy? No .
Most rods, especially 6wt and above and even some lighter rods are designed to load optimally with more than 30ft outside the rod tip. This may be 35, 40, even 45 ft. By building a rod like this it will work with the rated line over a wide range of short to long casts. It varies with line taper, but each extra 5 ft or so of line beyond 30 adds about the equivalent of one wt size in load on the rod (this is a generalization and the specifics will depend on the line taper and spot in the line measured). So our 7wt rod may very well be designed to optimally load with 40-45 ft of WF 7 line, which weighs about the same as the first 30ft of a 9wt line. A 9wt line is nominally 240 grains for the first 30ft or just a little less than the 250 grain line in my example. So that 250grain line will work fine with a 7wt rod.
As I indicated, line manufacturers usually give recommendations of matching rods, sometimes on the box, but usually in the print or web catalog. Some do not, but you can look at ratings from similar lines from other makers to get a feel. The boxes or catalogs will usually give a sink rate for the line.
As Silver Creek said, grain wt does not by itself indicate a sink rate. A 300grain floating shooting head floats and a 300grain head sinks. Usually, the heavier sinking head is, the faster it sinks but this is not absolute since density of the line is the determining factor.
Just to clarify, Silver Creek of course meant to say that the “Type” refers to “inches per second” or ips (not feet-per-second).
While there are a lot of different sink rates on lines, in the West folks usually restrict themselves to an “intermediate,” Type 3, and Type 6 line for most fishing, whether you are talking sink tips, shooting heads, or full sink lines. There are some faster sinking lines for really getting down fast (e.g. when striper fishing, BC steelheading, etc.) but for steelhead fishing, these 3 weights cover the majority of situations. I’ve no idea how different Great Lakes steelheading is from fishing CA rivers, but for traditional swinging a floating line or an intermediate sink tip (usually on a spey/switch rod) is about all you’d need, and a type 3 & 6 head is good to have just in case. YMMV.
Thanks. It is inches per second adn not ft per second. I’ll fix the original post, but I wanted to thank you for pointing out the error on my part.
I’d like a line that sinks at 3 feet per second, but I suspect it would be a bear to cast.
Not at all. Leave it on the reel and “cast” it overboard. That ought to sink at somewhere about 3’ per second. 
Faster I think. From personal experience. Rod/reel was recovered.
Like some of the others have mentioned…You’ll be worry with the 10wt rod. It’s too heavy for Great Lakes Steelhead. You would do much better with a 7 or 8wt rod…and the longer the better. I have a 9.6ft 8wt…and if I had it to do all over again…I’d probably go with a 10-11ft 7 wt, but the rod I have works fine for me around here. It’s beefy enough for the odd Chinook salmon that may latch on in the fall.
Most of the steelhead fishing around here is done with a floating line and a strike indicator. The odd time a sinking head line comes in handy (swinging streamers on the bigger rivers). In Michigan and some other areas… the “chuck and duck” method with a running line is common. It’s frowned upon in my local tribs.
I have the Rio “Dredger” Versitip fly line. It comes with three different wt heads for slower or faster sink rates. You can purchase more or make them. Not cheap and to be honest, I haven’t had much of a chance to use it yet. Hopefully the conditions are better this year.
Thanks to all!! You probably saved me some money assuming that my 8wt. will even handle the occasional salmon or even saltwater flats fishing. Thanks again to all! It was an educational experience for me.