Several accounts purporting Joseph Smith’s attempts to walk on
water using boards appeared after his death. For example, the following
account appeared in an 1869 gazetteer:
Joe Smith, the founder of Mormonism, operated quite extensively in this town and
vicinity during the early years of his career as a prophet. To convince the unbelievers that he did possess supernatural powers he announced that he would walk upon
the water. The performance was to take place in the evening, and to the astonishment of unbelievers, he did walk upon the water where it was known to be several
feet deep, only sinking a few inches below the surface. This proving a success, a second trial was announced which bid fair to be as successful as the first, but when he
had proceeded some distance into the river he suddenly went down, greatly to the
disgust of himself and proselytes, but to the great amusement of the unbelievers.
An apocryphal story about Jemima Wilkinson relates that one day she led her colony to the shore of Seneca Lake and told them that she was about to walk upon the water. First, however, she tried the surface gingerly, and when her toes broke through she returned back unabashed to shore, saying cooly that her followers' faith was already of such prodigious strength that no miracle was necessary.
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No Man Knows My History
There is a similar, and equally apocryphal story about Joseph Smith, which holds that he too boasted he would walk upon the water, but that he secretly built a plank bridge underneath the surface of the pond. The public demonstration was a notworthy success until he reached the middle, when, thanks to mischievous boys, instead of planks he trod on water and barely escaped drowning.
http://solomonspalding.com/Lib/Brd1945b.htm