No, I'm not talking about the after effects of the holiday season. What I'm talking about are rods and line weights. A lot of people have questions on if they can use a 6wt, or even a 7wt, on that 5wt rod that they love. But they are afraid that they will cause some untold catastrophe to the rod if they do.
Let's see if we can't clear some of this up.
Let's say Joe Blow the Ragman's Kid starts making rods out of his Pop's basement. He determines that he wants a medium action rod, and that he is going to make it out of graphite. He then determines that the graphite composition is going to be XYZ.
So he goes and gets a blank made with the XYZ composite and builds himself a rod. Now that rod will only have the desired medium action if used with a line weight of ABC grams. So if the rod gives the proper action with a line of 185grams, then Joe Blow the Ragman's Kid will say he has a medium action 7wt rod. (Click Here to check out a chart for fly lines and their gram equivalents.)
But now Joe Blow the Ragman's Kid wants a fast action 3wt. Does he design a new rod? Heck no! He takes that rod he just made and slaps a 3wt label on it and markets it as a fast action rod. Why?
Because the 3wt, weighing in at only 100 grams, will flex the rod a lot less than that 7wt line, resulting in a quicker responding rod. Or in layman's terms, a fast action rod.
So can you safely take that 5wt rod and put on a 4wt, 6wt or whatever line on it? Of course you can. But I would urge to take a common sense approach to it. I would strongly advise against taking a 2wt rod and putting a 10wt on it. The amount of stress that you will place on that tiny rod with that hefty line will, in time, give the rod a beating and probably cause a failure in the future. But there is no cause of concern if you stay within a line weight or two of the "recommended" line weight.
But if you have a rod you love but wish it would be a little bit slower, or faster, then I would recommend playing with line weights and fine tuning it to your casting style. When it comes down to it, the rod is just another tool in your fishing arsenal. One that can be fine tuned and adjusted to fit your needs.