Question of the Week: July 8, 2020

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Can I use a 5 weight line on a 4 weight rod?


I say no.  However you are going to hear from many anglers that say yes you can.  You will even hear that on every media outlet pertaining to fly fishing.  You will even hear that from fly shops and guides.  So there are many angles to this answer.  However I’m a science guy, if a fly rod says 4 wt. on it then it’s designed to cast only 4 wt. line.  If it were designed to cast 5 wt. line it would say so.  So in short a 4 wt. fly rod is manufactured and designed to cast only 4 wt. fly line.

We as fly anglers get caught up in what is the best rod for this or that.  We look at the label of a rod as a status symbol and are crafty in how a good rod makes us cast better.  However, we lose sight on what a good dry fly rod is designed to do.  What a good dry fly rod is designed to do is cast the weight of the fly line you choose to use.  A good dry fly angler chooses to use a fly line that gives him the properties and weight of the fly line ( Fly line weight = how heavy the line is) he or she desires in their cast and presentation.  Another way to put it we cast fly line and not a fly rod.  It’s the fly line that gives us the results we desire.

For me, a 4 wt. line gives me the lightness and smoothness for a softer presentation.  So I match that with a quality 4 wt. fly rod.  I will change to a 5 wt. dry fly rod when the conditions demand it such as a strong breeze or wind.  The weight of a 5 wt. line  will give me the extra weight in the line to cut through the wind.  What weight line and the corresponding fly rod you use is a subjective thing and each angler will give you a different answer to why they prefer one weight over another.

I suppose like most things if fly fishing, you could use 5 wt. line on a 4 wt. fly rod and do fine.  I could also use my putter to tee off and my driver to putt.  Tight lines….