Sparring was a means of actually lifting the bow of a steamboat as if on crutches, up and off a sand bar with stout spars, block and tackle, and the use of the paddle wheels to lift and move the boat through successive stages, over the bar. This booming a boat off a bar was by it's very action know as "walking the boat" and "grass-hoppering." Two long sturdy spars were forced forward from the bow on each side of the boat into the sand of the bar at a high degree of angle. Near the end of each spar a block was fastened with a strong rope or hawser passing through the pulleys which went down through a pair of similar blocks secured on the deck near the bow. The end of each hawser went to a capstan, which when turned would tighten and with its weight on the spars, slightly lift the bow of the boat. Engaging the paddle wheels forward and by the placement of the spars caused a lifting of the bow off the sand bar and moving the boat ahead perhaps a few feet. This was laborious and dangerous work for the crew even with a steam driven capstan. (description by Michael Marleau; thanks!)
grass-hoppering
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