Fly rod weight

Question
Hi!
I just got a 4wt rod to add some variability from my 6wt I typically use.  It is constructed of IM8 graphite and the maker (independent) recommended a slightly heavier line, such as the 4 wt Sci. anglers GPX to accomodate the IM8 reflex.  I bought the rod primarily for more delicate presentation, but also for a lighter feel and more fun playing small to medium size trout.  Curiously, the rod does not appear that much different from my 6wt (diameter of blank) and is stiffer, though is supposed to be medium action (my 6 is med-fast).  The maker professes that this rod will perform very well with the right casting stroke (short, quick).

Question: is the rod's ability to cast a 4 wt line all that matters, or should I wonder about the relative weight/appearance of the rod compared to my 6 wt.  I wonder if I should have gone w/ a 3 wt, but didn't want to lose ability to cast size 6 or 8 streamers when I wanted to w/o switching rods.
Thank you!
Mike  

Answer
Mike


Trying to judge rods by their diameter can be misleading. A rod with large diameter with thin walls can have the same power as a rod with small diameter and thick walls. Different companies judge the power of their rods to there own specs so the same rod could be considered fast action to one company and medium action to another. The way they rate the power of rods also varies one company's four weight could be another's five. One of the best ways to judge is try different weight lines on the rod to see which one it casts best. I know this doesn't help much but there just isn't a lot of standardization in the rod building industry.

Thomas F. Thornhill