CTD construction

Starting on the construction of a conductivity/depth/temperature sensor system.  These CTD systems are used by oceanographers and limnologists to measure chemical parameters in water.  The initial work is based on the SeaPerch project at MIT.  They released a prototype version of a system in 2010 but it appears to have not gone beyond beta testing.
So starting from their hard work, I am going to make some adjustments and hopefully improvements.

The brains are the arduino microcontroller and then I will use an Adafruit Datalogger shield - I am using an old one and Lady Ada now has a more refined and improved shield but that maybe for version 2.
Just like the SeaPerch version, I started with an Otterbox and will use similar sensors except a 10K thermistor from adafruit. I used an array of these thermistors in a chain under the ice for the winter and they worked well.

So first thing is to drill holes for the sensors

Thermister on left 5/32" hole, then two 1/16" holes (1 cm apart) for conductivity probes,
and then a 3/8" hole for the depth/pressure sensor

Drilling holes needs a little jog to keep it all stationary

Tightening the barb for the pressure sensor

Testing the resistanc eof the thermistor before pouring epoxy

Sealing it all with epoxy - tape to protect the watertight seal

Titanium rods are 4cm long

Ventilation with epoxy is essential