Hi Dan,

As usual all the responses here are very good and very complete.

A high percentage of the time with a fly rod rated for two line sizes, it
would be best with the heavier size. In the past I have seen some really
soft rods that were better with the lower number.

The old adage as stated here in other excellent posts is "DT4/WF5".

Many choose DT lines for shorter distances, mending , roll casting,
short-line nymphing and accuracy.

For open water, most use WF lines. A fact is that the best selling fly line
is a WF5F. Next is a WF6F. I am not promoting anything here, just stating
industry "sell through" facts.

A "double taper" line "loads" (feels heavier) a rod better than a "weight
forward" line at short distances because it's front taper in shorter. Most
DT trout line front tapers are ~8' long and weight forward trout line front
tapers are 10' to 12'. This means that with a DT line you get more belly out
beyond the tip of the rod adding more weight.

--
Bill Kiene

Kiene's Fly Shop
Sacramento, CA, USA
www.kiene.com

"Dan" lose wrote in message
...

If it is as crucial as I have been led to believe that the line weight
matches the rod weight, what weight line does one use if a rod described
as
a "4/5" weight?

Dan