How can I determine line weight for an unmarked blank?

For a fly rod, or casting/spinning rod?

On casting and spinning rods those type ratings are very much subjective. Some companies just list a line weight range that they feel is suitable for the type fishing that such a blank would be employed in. Others use a range where the top end doesn't exceed the deadlift capability of the blank. Overall, it's not of much use either way - anglers generally know what line they need for a particular fishing situation and choose the appropriate line for such use. The blank or rod doesn't really factor into it other than when someone does something silly like taking a light power bass stick and puts 80lb test on it and decides to use it for bottom fishing. Any good rod builder should be able to shake or waggle a rod blank and give you a good idea of what line range would be appropriate for it.

Now if you're talking about a fly rod, you need to determine the blank's power. Do that with a CCS measurement. That will give you the rod's power (ERN). From there, you can use the equation ERN = ELN and calculate the line that should do well with 30 feet of line past the tip. If you fish in much closer, try ERN = ELN+1. If you fish out much farther, try ERN - ELN-1. I think you'll find that works very well but you can still tweak it a bit until you find what you prefer.


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Generally speaking you can simply measure the diameter of the tip and compare this tip to commercial blanks. This diameter will give you information that is good enough to figure the line weight.

If the tip is heavy enough to carry a particular line weight; the rest of the rod will carry the line.

Take care
Roger

Roger, i gotta disagree heartily on that one

one example, fly rod, [www.batsonenterprises.com] - the batson RX8+ line - from 4 wt to 10 wt - all of them have a 4.5 tip except for one of the 8 wt models, its has a 5.0 tip.

now if we are talking spinning casting rod - the same thing applies, with rods marked for the same line range, but the tips vary as much as 1 or 2 64ths

I'm with Joshua. Line weight is generally estimated by the manufacturers based on anything from anticipated lure weight to anticipated fishing styles to the action of the rod, and possibly a number of other esoteric (not to say arcane) factors, and is stated as a relatively narrow range in order to support the stated lure weight. Or so it seems - you can't get a simple answer from the manufacturers.

In fly fishing line weight is paramount because there is no stated lure weight (flies being what they are, even if they have lead core and beaded eyes and all manner of interesting stuff in the body and wings). An old axiom is that you are casting the line, not the fly,and so grain-weight of the first 30ft of line is the defining "line weight", Unfortunately, a lot of years ago, many rod manufacturers started listing their rods with a "spread" of line weights (i.e., 6-7, 2-3, etc.) instead of the older way (i.e., a 7'rod for 6wt line, which was simply stated as 7'6wt). So how do you know what the right line weight might be? Well, the minimum would be the line that fully loads the rod with 30' of line out.

In casting or spinning the line has to support the lure. The lure weight is stated in a range as well - ususally, with a quarter or half-ounce spread, but sometimes more (i.,e., 1/4-1/2oz). The lure weight is usually rated conservatively compared to what the rod might actually do, in order to prevent someone from throwing something that will not only load the tip, but snap it. It's a really good way to avoid warranty claims. How to tell what it'll do? Well, you can match it on a pegboard with a rod that has a known set of specs. See what the curve is under load, say, 1oz. If the two curves match, you're close. But if one of the rods has a significantly thicker tip than the other, the test only tells you about the relative actions, not the load range. Find a marked rod that's comparable in tip dia. 1/64 is not that significant, but 2 or more is.

The line weight will generally fall into a range such as, 6-10, 6-12, 8-12, 12-20, or something like that. The idea is that for the hqeavfier lines it's not the fish, it's the brush and stumps and such you have to deal with. It could be the fish, too, but the best example I can give you is going after 5-10lb bass with 20lb line; why you would do that is because you're expecting to drag them out of heavy cover.

- hope that helps

Uncle Russ
Calico Creek Rods

Thanks guys for your input..I should of specified that the blank in question is a fly rod blank. Tom, I would like to get more info on ccs if you could point me in the right direction.

thanks.......Bruce

Go to the upper left column on this page and the Common Cents Info is the second item. Right below it is the CCS Data Site where measurements are stored.

Stan Grace
Helena, MT
"Our best is none too good"

Tom, the sponsors column on my screen is blank except for three names, they are diamond 11 epoxy, double LL fly rods, and the pro staff

Bruce

Bruce,
Disable your "pop up" blocker and you will see the rest
of the sponsor list.

Raymond Adams
Eventually, all things merge, and a river runs through it..