Beware of mistaking “diameter” for “circumference” when discussing the size of cordage in ship's rigging.
Traditionally, nautical cordage (“rope”) has always been measured by circumference. I've read this is because rope makers quickly learned that the amount of material – hence cost – in making a rope is more easily calculated from circumference rather than diameter. Maybe so, maybe not. But, a “1-inch” manila line in traditional measurement is actually about 1/3-inch in diameter, probably 3/8-inch in reality. This is well suitable for the purpose of a messenger, but hardly big enough to carry a man aloft.
That 4-inch circumference cable works out to be about 1 1/4-inch in diameter, which matches what we see in photographs of the funnel stays.
The concept of measuring cordage by circumference may be steeped in tradition, but it's a bit confusing to the uninitiated. These days, American yacht shops sell rope of all sizes up to 1-inch by diameter. Ship chandlers sell larger cordage for commercial use. Everything over 1-inch diameter is still measured by circumference.
Now, it's time for a piece of pi.
– David G. Brown