Fly rods are designed to utilize a certain weight line on them, but sometimes changing from a lower or higher line weight can change the rod’s output. I own several of the older Scott G Series rods. While I know that these rods will never compete with the lighter, faster rods that are coming out today, there is a certain feel about them. I love fishing them, but often times find myself wondering what a different line would feel like on them. Recently, I got a new 4wt. Rio Gold fly line for a Scott S4 Rod. While Rio claims this is an all purpose fly line, what I have been told is that this line is a bit heaver than just a 4 wt. For instance, my 4wt. Rio Gold is more like a 4.2 Wt. line. When hearing this and looking at the tapers of the line, I figured that a 4.2 wt. line would not be the best choice for a slower rod like the G Series. If anything, I should go lighter, not heavier. Most of the weight of these tapers is at the front of these lines.
For a new rod like the Sage One or Hardy Zenith, this line might be a bit light and these rods might require an even heavier line, such as the Rio Grande or SA GPX for their fast tapers. These lines are a ½ size heavier than stated, so a 4wt. Rio Grande is actually like a 4.5 or 4.6 wt. line.
So going back to my G Series rod, I took an 8’4” 4wt rod out for a spin with a 3 Wt. Rio Gold line. Usually I use a standard Rio Classic or Rio Selective Trout line on these rods. These lines are not offered by Rio any longer, but that is what I have for them. They cast great with those lines as they are more of a “standard” line. A 4wt. is a 4.0wt. line. When I put the rod and line together, it was like a new rod! By getting a slower rod like the 4 wt. G, and putting on a light line like the 3.2 Wt. Rio Gold on it, the rod was just a bit more responsive and quicker. If you have ever tried to cast a fast rod with a standard line, it can almost feel lifeless. If you up-line it, then the rod may actually wake up and start to breath. In this case, by underlining it, it felt like the rod was “perkier”. Even though it was still smooth as butter, it had a different feel. Casting this same rod with a SA 4wt GPX line, the line and rod felt heavy and sluggish. So I encourage you to take some of your rods out and mess around with a few different lines on them. Borrow your buddies’ reels and see if a particular line works better on your rods. They may find a line that works for them as well.