Documentation and support for a bristlemouth-integrated tide gauge buoy, using parts and software borrowed from the OpenCTD.
Read about the project, and the work of the St. Michaels Climate Change/Sea level Rise Commission, here: St. Michaels Floodwatch
The Tide Buoy uses an Adafruit Feather RP2040 connected to the Bristlemouth DevKit via an OpenCTD carrier board. The pressure and temperature sensor is a MS5803-14BA on a DIY circuit board (but a commercial breakout board is available from Sparkfun.
The pressure sensor is potted in a 3D printed housing that is screwed, along with a spacer, to the bottom of the DevKit. The 3D Parts File can be found here: 3D Printed Parts. A Blue Robotics WetLink Penetrator is used to routh the wires through the base of the DevKit housing.
To prepare you Spotter Buoy, reference the Bristlemouth Development Kit User Guides and, especially, Bristlemouth Dev Kit Guide: Serial Client for CircuitPython. A circuit python library and sample code for the pressure sensor is provided here: MS5803-14BA and the python script to run on the tide buoy, which is currently set to sample once every 15 minutes, is available here: code.py.
Real-time date from the tide buoy can be charted over a 24-hour cycle using this html script: chart while the last 12 sensor readings can be recalled using this html script: readings. Barometric pressure is normalized against the most recent reading from the NOAA Annapolis weather station.
Correction factor for MLLW: 1.8
Correction factor for MSL: 2.3