Horse riding, spanker boom punishment for men

[megarun]

On one forum, I found a comment with a link to a book about punishments (George RILEY Scott, ‘History of Corporal Punishment’, 1938):

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The miscreant had his hands tied behind his back, whereupon he was stripped to the waist and made to straddle the ‘spanker’ boom much in the same manner as described in riding the military ‘pony’, except that lashed to the boom was a swab (mop-head) that had been well-saturated with gunpowder which caused an almost unbearable maddening burning and itching to the unfortunate lad’s genitalia and posteriors.

The ‘spanker’ boom was so-named because it rose and fell more or less in rhythm with the ship on the open seas, similar to the action of the (children’s’ playground) ‘teeter-totter’ apparatus, the only difference being the actual fulcrum being mounted on the end rather than in the center.

Consequently, the punishment was determined not by the usual fixed number of lashes but by the amount of time the offender was sentenced to spend astride the ‘spanker’. It was the motion of the sea combined with the movement of the ship which provided the actual punishment.

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I do not know English well and it is difficult for me to look for additional information on this issue.

I could not find the mentioned book.

If you know what this technology of punishment is, then please explain to me.

How was a man fixed so that he would not fall?
Did he sit on his balls?
At what distance from the ship did they put him on a beam?
Have they always used a swab (mop-head) with gunpowder?

[megarun]

I found some drawings.