Odds 'n' Sods of Information and Opinion

The Carrying Weight Concept

Since 1961 the AFTMA rod and line weight rating has served us pretty well, however with advances in lines and rods, it’s showing its age. No one is going to get rid of this system any time soon, but perhaps it’s time to add another line rating concept to cover all of the types of fly fishing being done today.

When this standard was developed only level and double taper lines were available. Virtually all of the fishing with single hand fly rods was aimed at trout. So the standard was built around a typical trout casting distance and throwing a typical trout fly using a double tapered line. The designers of this system arbitrarily chose 30’ of line as the standard for a typical trout cast. That statement is not an implied criticism as any line rating system by default has to be arbitrary.

So what relevance does a system based on a 30’ trout cast have for casting 80’ to a cruising permit or hucking a dead rabbit for muskie? The answer is, “Not much.”

While modern fly rods are built to the AFTMA standard they can in reality handle far more weight. Let’s use a 9’ 5 wt. as an example. This rod is built to cast over typical trout fishing distances 30’ of 5 wt. trout line weighing 140 grains. Yet there are distance 5 wt. lines available with heads that are upwards of 60’ long and have head weights pushing 280 grains that this rod will handle without difficulty. That’s the same as the AFTMA rating for a 10 wt. rod!

This ability of a rod to carry far more weight than the AFTMA standard would suggest, is at the heart of the Carrying Weight Concept. It isn’t intended to supplant the AFTMA system, rather to complement it. It’s primarily an advanced concept to be used by experienced anglers to fit the right line for their rods to handle any reasonable fly fishing situation they might encounter.

The Carrying Weight Concept is a very personalized one as the lines it suggests can be different from one angler to another. It covers:
  • How much line weight the rod can handle, in other words “carry”
  • How much line the angler can false cast and forward cast, in other words “carry”
  • What species being targeted (covers fly size, distance, presentation requirements, etc.)
  • Fishing conditions (covers casting room, wind, casting position, etc.)
The primary one however, is how much line weight the rod can carry as that is a constant across the other three criteria.

In its simplest terms, the Carrying Weight Concept identifies how much line a rod can carry. So for our 9’ 5 wt. example, if it can carry 250-280 grains, this means that
it will be able to cast for distance any line with a head weight in that range. So if I need to cast a big popper to smallmouth with that rod, I could use as much as a 35’ to 38’ short head WF-7-F or WF-8-F bass line to do the job and the rod will handle it comfortably as those lines are within the Carrying Weight limit for that rod.

The intent of the Carrying Weight Concept is to get us out of the habit of thinking that the AFTMA standard is the end all and be all for selecting fly lines for our rods.

Thinking in terms of carrying weight for distance casting on my 5 wt., we could use a long head 5 wt., a medium head 6 wt. or a short head 7 wt. and they’ll all produce about the same rod loading. Which one of those we would choose would depend on the other three criteria of ability, species and conditions.

The easiest way to determine the carrying weight for your rod is to cast a double taper line of the same rating, marked off at 5’ interval starting at 30’. Start at false casting 30’ of line out of the guides and then increase by five feet until either the rod or your casting ability reaches its limits. This test quickly establishes either your personal carrying weight or the rod’s. If you max out first, find a buddy who can handle more line to try and establish the rod’s limits. That’s important to know as you may well be able to easily handle a shorter head line of that weight.

My next blog post on this subject will contain a spreadsheet that will calculate the weight of an AFTMA accurate fly line for any length of head. We can use it to determine the weight of any length of our double tapered test line, based on the length out of the guides. We can use the spreadsheet to find the weight of any AFTMA accurate line without owning a grain weight scale, including typical weight forward lines.