Dubuque to Sabula, IA

As we headed south from Dubuque we said goodbye to Wisconsin, which is no longer on our port side—Illinois is our new companion. We plan to visit the Badger State again next year, when we come down Lake Michigan from Mackinaw Island to Chicago. We left Port of Dubuque Marina with our new friends Chris and Kathy close behind, but their smaller outboard couldn’t keep up, so we slowly pulled ahead. We passed quite a few barges today, a couple of idle dredges (they get Sundays off), and the Twilight, a 140-passenger, riverboat cruise ship that was waiting to enter Lock 12 as we exited. We went 45 miles downriver to Sabula, the easternmost city in Iowa, in perfect 70F weather with a light breeze at our backs, cooked dinner onboard, toured the island hamlet on foot, then relaxed until bed time. Tomorrow we’re continuing on to the Quad Cities.

Today’s navigation lesson is on daymarks. Similar to buoys, they indicate the edge of a channel, but daymarks are fixed on shore or to the river bottom, while buoys are floating. Green daymarks are square (like a can buoy, see below), while red daymarks are triangular (like a nun buoy).

There are special daymarkers called crossing marks, which indicate when the main navigation channel shifts to the opposite side of the river. For example, the crossing mark below that we passed today is doing triple duty: it acts as a red buoy, showing the eastern edge of the channel; it tells you that the channel is shifting over to the west side of the river; and it acts as a signpost, telling you what river mile you are passing (572.6).

For mileage and location purposes, the Mississippi River is divided into Upper and Lower segments. The Upper Mississippi begins at Mile 866 in Minneapolis and ends at Mile 0 in Cairo, IL, where the Ohio River joins in. The Lower Mississippi begins there and counts down until Mile 0 again in Louisiana below New Orleans. Fun fact: Rivers in the U.S. are measured in statute miles, same as on the roads, while nautical miles (about 15% longer) are used in coastal and ocean areas.

We are still traveling through beautiful, mostly wild river valleys and wetlands, although we’ve learned a lot in the last two weeks about the impact of modern humans in their efforts to tame the river to suit their needs. We regularly see things along the way that are impressive feats of engineering, creators of jobs and opportunity, but also reminders that the river has been changed forever.