Surface water temperatures across the Great Lakes and connecting waters in 1965 determined using a ship engineer’s log onboard the SS Bayton
Description
Background: The Great Lakes are undergoing climate change resulting in the predicted loss of winter ice cover and limited data available for assessing model predictions of future changes due to climate change ((Xenopoulos et al., 2024). Limited historical data sets of water temperature are available from water treatment facilities but these reflect nearshore temperatures only. Satellite imagery using Advanced Very High Resolution Radiometry (AVHRR) of sea surface temperature in the Great Lakes began in 1992. Therefore, any earlier pelagic surface water temperature data, such as this dataset, is valuable for establishing models of water temperature changes in the Great Lakes due to climate change. Algoma University (Sault Ste Marie, Ontario) contains an archive of Great Lakes ship captain and engineer logs dating from the 1930s. One log, that of the SS. Bayton, contains seemingly accurate water intake temperatures recorded routinely in the engineer’s log during transit and in port. Archive: The log is a complete record of voyages by the SS Bayton throughout the Great Lakes and St Lawrence River dating from April 18 to December 1, 1965. The gap in the record between June 28 and July 8, 1965 was due to quarantine in Port Colborne, ON. The engineer recorded surface water temperature measurements in Fahrenheit at 4-hour intervals while in transit across lakes, rivers and canals. Data sheets: The “Georeferenced time-stamped surface water temperature across the Great Lakes (April to December, 1965) - Master sheet” file is a digitized version of the engineers log. It contains a summary of dates, times, transects (departure and arrival points), and surface water temperatures directly copied from the log. This data was used to calculate distance (nautical miles), duration (hours), and speed over ground (SOG, knots) for each transect. Between departure and arrival points, surface water temperature measurements were made at 4-hour intervals, recorded as “Counter@” or “Counter temp press” in the “Place end” column of the file. The latitudes and longitudes of surface water temperature measurements were estimated using the distance, duration, and speed over ground calculations. The “Decimal lat long date and surface temperatures across the Great Lakes and St Lawrence River, April to December 1965” file is a summary of the “Georeferenced time-stamped surface water temperature across the Great Lakes (April to December, 1965) - Master sheet” file. It contains day of year (DOY, 1965), time (decimal year), and decimal latitude and longitude for each surface water temperature measurement. Reference cited: Xenopoulos, M., Twiss, M., & Child, M. 2025. Great Lakes Winter Science: Summary Report. A report submitted to the International Joint Commission (IJC) Great Lakes Science Advisory Board, IJC-Great Lakes Regional Office, Windsor, Ontario. https://ijc.org/sites/default/files/SAB_WinterScienceReport_2025.pdf
Files
Steps to reproduce
The digital data provided here are derived from the handwritten engineer’s log of the SS Bayton voyages on the Great Lakes and St Lawrence River from April 18 to December 1, 1965. The engineer’s log is available from the Algoma University Library and Archive: Engineer's Log, S.S. Bayton, St. Marys River Marine Society Collection, File: 010-206-003-011 OS, 1965, Algoma University Archives, Sault Ste. Marie, Ontario, Canada. Methodology: Using the photographic images of the engineer’s log (referred to herein as “the log”), the starting and ending point for each entry was determined. The time of departure and the time of the next recorded waypoint were recorded. A time duration calculator (Calculator.net, 2026) was used to determine duration of travel between entry locations, and between starting point and time of sea temperature reading. The engineer logs “sea temperature” in degrees Fahrenheit; this refers to lake surface water (drawn in from a depth less than the ship’s draft of 8.5 m) used for the steam boiler in the engine room. There are instances where “time of record” differs from departure time. In such cases, the departure time was recorded in the “time start” column, and this time was used to calculate the duration of the trip. The departure time is also recorded in the “notes” column of the digital data file. The latitude and longitude of each location was determined using Google Earth (Google, n.d.) Google Earth uses spherical and ellipsoidal coordinate systems (the WGS84 - World Geodetic System 1984) geographic coordinate framework, which represents the Earth as a 3-D globe using latitude, longitude, and elevation. Waypoints were placed on the map that represent places where shipping lanes alter course (bearing). All times were recorded as day of the year in 1965. The locations and times at each recorded point in the log were used to determine average ship speed over ground (SOG, knots; nautical miles per hour) for each transect (where a transect is the distance on a constant bearing along a cruise track). Known shipping corridors (Hill, 2003) were used to establish cruise tracks between waypoints. The calculated SOG for each transect was used since it can be affected by wind, current, ice, and traffic. The location at the time of the data entry of sea temperature was estimated using the distance travelled based on velocity from the last known waypoint. References cited: Calculator.net. (2026) https://www.calculator.net/time-duration-calculator.html?starthour=17&startmin=02&startsec=0&startunit=p&endhour=20&endmin=00&endsec=0&endunit=p&ctype=1&x=Calculate; Accessed 20-July, 2026. Google. (n.d.). Map of the North American Great Lakes-St. Lawrence River System [Google Earth web application]. Retrieved May to July, 2026, from https://earth.google.com/web Hill, A. 2023. Mapping the Great Lakes: Freighters! Great Lakes Now, https://www.greatlakesnow.org/2023/05/30/mapping-the-great-lakes-freighters/; accessed June 9, 2026.
Institutions
- Algoma UniversityOntario, Sault Ste. Marie