Looking NE from I-64 on-ramp near 10th St.
Towboat "Vicksburg" (doc. # 290399) downbound approaching Portland Canal.
Conrail (later L&I) Bridge and upper gates of McAlpine Dam at upper left.
Ohio River mile 605.
file # 88b077.
Beyond the boat is a vane dike built to modify the current which, when the gates of McAlpine Dam are open to let water pass, runs from near the Kentucky bank toward the open gates. This current (called outdraft because it flows out away from the bank) tends to push downbound tows toward the dam instead of into the canal where they want to go. As I (no expert) understand it, the vane dike deflects some of this outdraft so it flows more toward the entrance to the canal. The diverted water then flows through a gap (partly seen at left) between the downriver end of the dike and the upriver end of Shippingport Island. The top of the dike is only a few feet higher than pool stage, so when the river rises significantly, the dike is submerged and has little or no effect. At the time of this photo, the upper gates were barely open, and while I don't know about the lower gates, I think the outdraft would have been minimal.
See a navigation chart showing locations of vane dike and McAlpine Dam.
35 mm Kodachrome.
Plustek OpticFilm 7600i and Silverfast 8.
Picture Window 6.
JPEG quality 95.