Public Lab Research note

This is an attempt to replicate an activity.

Cape Cod Thermal Fishing Bob Field Test

by kgrevera | July 06, 2015 15:58 06 Jul 15:58 | #12034 | #12034

Cape Cod Thermal Fishing Bob Field Test


Becca and I took the thermal bobs to Cape Cod, MA to test them in the salt marshes. We tested out Laura Perovich's multiple thermistor bob and my kayak towable floatie rig and foam sled and toy boat towables rigs. The purpose behind this field test is to test out our improvements on the thermal fishing bob concept. The towable rigs will be described here. The multiple thermistor bob will be explained in another research note.

Research Questions

  • Will the rigs survive being towable behind a kayak?
  • Which rig design will have the most success?
  • How do I keep the fishing bobs themselves waterproofed to prevent damage to the circuitry inside?


We attached the rigs to the backs of two kayaks, the boogie board to one, and the pool floatie and toy boat to the other. The pool floatie has a handle made of duct tape. We tied a lead from this handle to the back of the kayak. The boat conveniently had a lead attached to it already. The sled we wound up tying a lead from the front handles, tying this to a tether on the kayak, to form a stable Y-shaped lead. We then paddled out on the water.


General success. The toy boat was certainly our dark horse. It floundered stupidly in the water at first, so we though it would flip over and not work, but it stayed stable and its tether held tight. In the future we will have to counterbalance it better. The pool floatie also worked pretty well, nothing got wet inside, but the handle wound up breaking and it had to be rescued. The handle will have to be further enforced for more testing. It just wasn't strong enough to hold up the the tide. The sled was also a surprising success. It kept the bobs safe and dry and trailed well behind the kayak. The only issue with it was when the lead snapped when my kayak got caught on a sandbar. This was mostly my error though, rather than a design flaw. I yanked myself free too hard and didn't notice that the sled was also snagged.

Next Steps

More testing! Better reinforced handle on the floatie rig and a counterbalance for the boat rig.


Screen_Shot_2015-07-06_at_11.45.43_AM.png Boat Rig

Screen_Shot_2015-07-06_at_11.46.35_AM.png Sad boat rig

Screen_Shot_2015-07-06_at_11.46.08_AM.png Sled rig

Screen_Shot_2015-07-06_at_11.47.23_AM.png Floatie and boat rig with kayak

Screen_Shot_2015-07-06_at_11.46.56_AM.png Floatie and boat rig closer up


Hi, just wanted to confirm that you're using multiple thermistors to get multiple depth measurements, and not to speed up your temperature readings -- I just posted a summary of the discussion we'd had in this comment and CC'ed in @kh_machine, @neilhendrick, @kgrevera, and @lperovich.

Looks like a great set of tests! One way you might go is to use a Digispark or similar very very tiny arduino, and solder your thermistor and LED directly to the board. Or just use the supplied headers, but they could fall out just like on your breadboard:


The Digispark is Arduino-compatible, but only $9, and about the size of a quarter. One RGB LED and a thermistor would fit in its 5 pins, and you could plug it into a USB battery like this:

Reply to this comment...

Reply to this comment...

Login to comment.