Hydraulic Effects

Sailing on the Great Lakes one sees a lot of “lakers.” In the roughly 4:45 minute run between the Soo Locks and Detour, MI, or nearly 9 hours running the St. Clair and Detroit rivers where close passage in restricted channels is frequent these are times that require extra vigilance. Running parallel course and too close to deep draft ships it’s easy to forget the hydraulic effects exerted by large displacement vessels. Around the bow high pressure exists on both sides of the ship as water is displaced. As that water flows along the sides of the ship it speeds up until it reaches low pressure near the stern. Too close and its easy for them to suck you into a collision or to be pushed out of the channel. Thomas J on Facebook wrote when they (the lakers) come by Lakehead Marina entering or leaving Duluth harbor they raise the level in the marina one foot. Shown Edmund H. Gott down-bound Duluth, MN. We’ve locked up and down with the Gott at the Soo Locks on two separate cruises and prior to our departure of Lake Superior would often see her taking on Taconite in Duluth, Silver Bay or Two Harbors.