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Mystic Generator Station Thermal Fishing Bob Event with Mare Liberum

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Please note that this research note is a work in progress with a group of contributors. Expect more content very soon.


Conduct a field test to examine the accuracy of the Thermal Fishing Bobs


Mystic Generator Station


September 8th, 2015


This is an account of the thermal imaging of the Mystic Generator Station using Thermal Fishing Bobs. A previous successful imaging occurred at the Kendall Power Plant. You can access that research note here. This event aims to duplicate these results.

Participants included the core Northeastern research team (Sara Wylie, Lourdes Vera, Anna Walsh, and Erik Hanley), a group of Northeastern University undergraduates, Catherine D’Ignazio (Public Lab organizer), Laura Perovich (MIT post-graduate student), two professional photographers, and the artist collaborative Mare Liberum.

The event took place at the gazebo south-east of Ryan Playground. Near the gazebo is a dock that led into the river where Mare Liberum set off their boats. All prep work (set-up of the bobs, tethering, ect.) took place at the gazebo.

The event was covered by The Boston Globe. You can access the article here.

First Run

The first run included Laura’s reel of fishing bobs. These bobs express the temperature of the water via color of light. They also log these temperatures to allow additional analysis. Three of these bobs were set with their thermistors at a fixed depth. There was also a variety of fishing bobs from Northeastern: One +85º F floatie (this served as the threshold), a 65-85º F floatie, and a 70-80º F floatie. The threshold floatie had two fishing bobs each with +85º F, both had their thermistor set at 3 feet. The 65-85º F floatie had one 3 foot and one 6 foot thermistor length. Last, the 70-80º F floatie had both of their thermistors set at approximately 1 foot. These floaties were attached to Mare Liberum’s boats to be taken to the discharge point.


-There were loud crashing sounds coming from the station at about 20:08. It sounded like a ton of pebbles crashing down on a sheet of metal. There were about 10 randomly occurring crashes.

-The short, loud, crashing sound occurred again at 20:17.

-There was a massive crashing sound at about 20:30. A plume of vapor was emitted from the older portion of the building. It lasted for about 20-30 seconds.

-It was difficult to see from the dock whether there was any color change from the floaties. It seemed that there was a constant green shade from Northeastern’s floaties and a blue shade from Laura’s floaties. The threshold floaties did not go off. We will have to see if there were any color changes from the boating crew.

-There was a brief and rapid change from blue to red at the beginning of the float out to the station. This was probably a minor glitch.

-As the boats floated past the plant, it was difficult to see the lights at all. We mostly had to hear through radio if there was any color change.

First run complete.

Second Run

We attempted a second round with a narrower temperature range 70-75º F. This was done in order to encourage a change in color, if possible. With a narrower temperature range, even the slightest change in temperature would result in a more significant change in color. There were two floaties, each with four fishing bobs instead of two. This was done in order to make the floaties more visible from the shore. One floatie had only long thermistors while the other only had short.

The boats went out and constantly stayed green all the way to the plant. After quite some distance, they became indiscernible from the shore despite the additional bobs. Once again, we had to rely on radio to hear what color change occurred. The boats returned and the crew mentioned that there was a slight green to yellow change.

We packed everything up and called it a night.

Second run complete.

Points for Next Experiment

  1. This should be done later at night. Some power plants tend to release late at night.

  2. We need to have a point of visibility that is greater for a long exposure picture. Maybe utilize the barge?

  3. We should have a video camera or a GoPro attached to the back fixed on the floaties. This video would provide better data for analysis.

  4. We need to do our next experiment later in the month so that the ambient water temperature is lower in general.



Setting off for Run 1


The light of the plant made it difficult to follow the light trails


Barge (left-hand mass in the river) may be a better location for second test


Team awaits Run 2


Set up for Run 2


Setting up for Run 2. Laura prepares her fishing bobs.


Set up for Run 2 is complete


Final long-exposure image of Thermal Fishing Bob trails



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