In article , Smudge
wrote:
Hi Derek,

"Derek.Moody" wrote in message
...
In article , Smudge
wrote:
Hi all,

I have a Hardy Sirrus #5 fly rod, and I was wondering what fly line I

Still waters, casting up to 20 or 30 ft.

OK, so nothing very critical, presentation before distance.

where you might go as far as a #7 - #8 or down to a #4.

Wouldn't using a high # line risk breaking the rod?

Casting a *weight* of line too great for the rod will do damage but at short
range you're only casting half a line - so the rod works best with a heavier
line. If you are aerialising a particularly long length when false casting
you may need to go down a size or (better if delicacy is not vital), switch
to a shooting head.

The correct answer is to work out how much line you need to cast, find out
what weight of line the rod really wants (by false casting a length of
too-heavy level line until you find the point at which the rod is working
'right' and then measuring and calculating) and then buy a line to meet
the
spec.

How is this calculation done, and is it accurate, come to think of it, how

Take a level line and weigh it. Say you have 20 metres and it weighs
40grams (this is roughly a #11, arbitrary value chosen for simplicity of
calculation) or 2 grams per metre.

Carefully false cast extending a little more each time until the rod is
working as you want - in other words until it feel 'right', if you are a
beginner you might get someone else to check this. *DO NOT TRY TO CAST THE
WHOLE LINE* or you will stress the rod.

Measure the length of line outside the rod tip. For ease of calculation we
will assume it measures 4.5 metres. So the rod casts 9 grams. Look up 9
grams on an AFTM scale and you find it equals a #5 line (the weight of the
first 10m of a #5 is 9gm by definition)

BUT

You are fishing at 20 - 30 feet (7 - 10M) By the time you take off 2m for
the length of the rod and 2m for the taper and leader you have only 3 - 6m
of line outside the rod and you will be shooting some of this. Let's say
you never false cast more than 4m of actual fly line.

The *ideal* line for your specific requirement, one that weighs 9gm in the
first 4m or about 2.25 gm/m is a weight forward #12. Of course if you cast
any more line with it you risk the rod.

In practice the better bet would be to buy a cheap mill end #7 or #8 and
cut it off at the 9gm mark so that it gives you help with the short casts
but can be used as a shooting head without straining the rod if you ever
need to throw farther.

do the rod makers test the rods for line weight.

The manufacturers test a typical example with a full line and then (I think
some subtract one to leave a margin for abuse) mark the whole production run
with the same number.

It would be nice if shops had a selection of all their lines ready for test
casting to see which brand and # suits the buyer.

Some do. Often angling booths at game_fairs/agricultural_shows have such a
facility with an attendant instructor.

Cheerio,

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