Perhaps this has been mentioned elsewhere, but would-be boarding parties were often "repulsed with hot water" from steam hoses aboard riverine vessels, to devastating effect. Several examples are recounted by gunner William L. Park on the USS Essex, including a failed effort by members of the USS Carondelet to board the Confederate ram Arkansas as she came down the Yazoo River to run the Federal fleet above Vicksburg (July 1862). Park's detailed, three-year diary is published in Two Civil Wars (LSU Press, 2016).