I recently purchased a 6wt cane rod and was playing around with different lines to see how they felt on it. Not much difference in a WF6F, DT6F, or a WF5F as far as performance at the ranges I was casting (out to 50-60'). The WF6F seemed to be the best all-round winner, so I went with it.
Then I read through a thread where I had asked about spey casting with a single hand rod. One member suggested overlining 2 sizes. I had picked up a reel with a WF8F line one day last year (by mistake) as I headed out with my Ross FlyStik 6wt rod, and the 8 wt line was WAY overloading that rod. It turned it into a sluggish limp noodle with very limited casting distance!
Just for a break in the monotony I grabbed a reel with a WF8F line and my new St Croix RioSanto 6wt 9ft rod this week to see what it would do. The rod threw the 8wt line very impressively! Spey, roll, and overhead casts were easy and accurate, but a bit of a slower stroke was required. The rod didn't seem to be nearly as overloaded and sluggish as the Ross rod had been. I actually got more line out on a roll cast than I have ever managed with a DT6F. I was so impressed I came home and ordered a WF7F line to try on that rod.
The rod casts a 6wt line very well, but it also handled being overlined 2 sizes with ease, and there are times a heavier line might be advantageous (big flies & strong wind).
All this got me thinking
so yesterday I got my Sage Vantage 7' 3wt rod that casts great with a WF3F and tried a WF4F line on it. It handled it with no problems and bucked the wind a lot better!
Looks to me like some rods are more versatile than others when it comes to line size, and I may have found a new way to extend the usefulness of some of them. For example, with high wind and limited backcast room I was still able to fish yesterday by simply putting the WF8F line on the St Croix 6wt rod.