Open Wave Height Logger prototype in the water

I finally got around to deploying a prototype OWHL unit in the real live ocean to log some waves.

The low-tech housing is made of 1.5″ schedule 40 pvc pipe. The pipe snugly fits the D-cell battery holder, while the electronics fit inside the modified 1.5″ end cap.

Components of the housing.
Components of the housing.
Prototype housing
Assembled prototype housing

I try not to rely solely on the tapered threads of the pipe fittings to be watertight. The screw-together parts of the housing also get a layer of polyurethane sealant when they are assembled. This makes disassembly a more strenuous affair involving a bench vise and a giant wrench, but that is low on my list of concerns compared to avoiding leakage.

The first lesson learned is that the little piezo buzzer I installed to serve as a pinger to prove the unit is alive and logging is far too quiet inside the housing. You can hear a faint, high-pitched beeping in the video above at ~43 seconds, but it’s far too quiet to be useful in all circumstances. That will have to be replaced with a larger, louder noisemaker. Additionally, our current method of isolating the MS5803 pressure port from the seawater (using a silicone tube filled with distilled water) is a major hassle to construct, and introduces a noticeable nonlinearity in the pressure response with increasing depth due to the springiness of the silicone tubing itself. These are both issues that will need to be addressed in future revisions of the housing.