From 'The Ashley Book of Knots' (ABOK)
#264.The FIRE-ESCAPE KNOT is for the same purpose, (climbing down to escape fire) but it is generally a fixture found in country and seaside hotel bedrooms. The proper way of tying is most interesting and is described at the beginning of Chapter 4, "Single-Strand Lanyard Knots." In England this method of tying has long been a part of the regular drill in rural fire departments, and it is now being taught in America, where it is sometimes called the "PHILADELPHIA KNOT."
The delightful tale below, also from Ashley Ch.4 p.93/94 gives a colourful explanation of how to tie "a hundred overhand knots" in 50 seconds, admittedly in smaller stuff than you intend, but the principle holds.
"There was, once upon a time, a sailor who had a sweetheart, The
girl was beautiful, and the sailor was handsome?so the girl thought.
But her father disliked all sailors, this one in particular, which may
have been because he had another husband already picked out for her,
a certain haberdasher's clerk, who had really very little to recommend
him save that he managed to keep both feet on solid earth most of the
time. That, as everybody knows, is too much to expect of a sailor.
But the girl found the haberdasher's clerk even less prepossessing
than her father found our hero.
When the father saw which way the wind was blowing he pleaded
with the girl, then he threatened and even stormed for a bit; but it
was to no avail, and the ship of True Love was practically on the
rocks.
But after a while the storm quieted down, as storms will. Although
the father remained obdurate, which means stubborn, the
girl too was stubborn, which means that she was her father's daughter.
But the haberdasher's clerk, although almost entirely devoid of
charm, was endowed with a certain native cleverness, and it was not
long before he thought of a plan which he communicated to the
father. Thereupon the father appeared to relent, and soon after he
suggested to his daughter that the selection of a husband should be
decided in fair competition.
Amid general rejoicing it was agreed that the suitor who could tie
the greater number of knots, while the father counted fifty, should
marry the girl.
Now the father had argued to himself in somewhat this fashion:
"Surely this haberdasher's clerk who does little from morning till
night, save knot ribbons and tie up parcels, should have no trouble
in besting this tarry-fingered son of a sea cook," But the girl needed
no one to tell her that her Jack would win, by a long sea mile.
On the appointed day and hour the father commenced his count,
and with nimble fingers the haberdasher's clerk tied OVERHAND KNOT
after OVERHAND KNOT, with such celerity and precision that a doubt
arose in the minds of the spectators whether his piece of string would
be long enough to last the full count of fifty.
In the meantime our hero, with apparent unconcern, and so deliberately
that it was maddening to watch, proceeded to cast one
hitch after another over his left thumb. "Forty-two, forty-three,
forty-four," counted the father; the race was practically over without
a single knot having been chalked up to the credit of Neptune.
The father was jubilant and had his blessing all ready. The poor girl
was in tears, the haberdasher's clerk appeared even smugger than
he had been before, but Jack remained calm as calm should be.
"Forty-five, forty-six"?the hitches completely covered his thumb.
"Forty-seven!" Our hero carefully tucked the lower end of his string
up through the center of the tier of hitches (which he had by now
shifted from his thumb). "Forty-eight! Forty-nine!" He pulled the
end through handsomely! (See Glossary for definition of handsomely.)
"FIFTY!" There on his string blossomed a hundred little
flowerlike knots, all neatly spaced and exactly alike!
The race was won; the haberdasher's clerk was ignominiously defeated.
There was nothing left for him to do but slink back to his
shop and hide behind the counter; and there, so far as we know, he
lurks to this day with his bit of string in one hand and his yardstick
under his arm."
See ABOK #564 "The FIRE-ESCAPE or PHILADELPHIA KNOT is tied at sea in jibboom footropes. A series of SINGLE HITCHES is first built up, one on top of another, each succeeding hitch being slightly larger than the previous one. Then the lower end of the rope is rove up through the center of all the hitches and is pulled out, one hitch at a time. This forms a series or chain Of SINGLE OVERHAND KNOTS which is of assistance in lowering oneself hand over hand. Country and seaside hotel fire escapes are often so equipped."
So, stack up a tier of hitches in your chosen rope, feed the end up and pull through and there you are- as many overhand knots as you like just needing fairing and setting to the correct spacing. Just be aware that you won't be able to get them out again once the rope has had some strain put on.
In ABOK # 565 a similar way to do this with figure 8 knots is shown, which are altogether more suitable for your purpose.
mmm so far havn't managed to upload the diagram-----