There are numerous instances on the Internet, and in Google books, that claim the cat-o'-nine-tails, a late 17th century instrument of punishment used by the Royal Navy, was kept in a bag. It is said that this bag was a necessity in order to protect the nine leather tails from the corrosive effects of salt water. However, the only evidence I have found of its existence is limited to 20th and 21st century accounts.
Taking the cat o'nine tails – a whip with nine leather strands, with the end of each one having a small knot – from its red baize bag, he dips the implement into a bucket of seawater, withdraws it, brings his right arm back well behind him and well behind him and then swings it forward. source (2019)
Discipline has always been demanded by the taskmaster of the sea. “He let the cat out of the bag”, said today, is often followed by an expletive. Six score years ago on board a square rigger, this utterance would have brought chills to the spine, for some poor soul had just committed an offense sufficiently grave to extract the cat-of-nine-tails from its canvas bag. Source (1979)
He took the cat of nine tails out of its linen bag and inflicted the requisite number of strokes under the watchful eye of an officer, who ensured that they were "laid on well." source (2003)
The bosun's mates stood by, one of them holding the red baize bag containing the cat of nine tails. source (1981)
A new cat was made for each flogging by a bosun's mate and kept in a red baize bag until use. source (post 2003)
“Boatswain's mate”, on which that functionary, drawing a cat-of-nine tails out of a little red or green baize bag in which it had hitherto reposed, administered the first swinging dozen … source (1902)
I was unsuccessful in finding any 19th century resources that mention a bag; linen, canvas, baize or otherwise, where the brutal whip was stored in. One EL&U user, in a comment said
If you visit museums, particularly near naval bases, you may see cat-o'-nine-tails, but you never see their mythical "bag". If bags were required for whips, we would expect a coachman's whip or a bull whip to have a bag.
Was this user's observations precise? Is this baize bag ‘mythical’, an invention to explain the origin of English phrase "Let the cat out of the bag"? Is there any evidence to suggest otherwise?