Braided line tends to run larger than the nominal diameter (Samson 7/16",
for instance, measures 1/2"), and I've never seen a synthetic line intended
for use as running rigging measure below. So your line measuring betweeh
5/16 and 3/8 is undoubtedly 5/16, and the other is undoubtedly 3/8.

Old line retains its original diameter, unless it's subjected to strains
near breaking strength.

HTH,
Tom Dacon

"Robert or Karen Swarts" wrote in message
...
I am about to replace the halyards and sheets on my 25' sailboat. I have
measured the old lines with a caliper, and had my neighbor repeat the
measurements to be sure they were consistent. The result is that the lines
measure between 5/16 and 3/8 for the halyards, and between 3/8 and 7/16 for
the sheets.

Does anyone know if old, weathered lines tend to measure more or less than
their nominal diameter? I.e., are these 5/16, 3/8 or 7/16?

BS