Specifications
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2.3 Service 
2.3.1 WR-SG and DWR-MkIII wave motion sensor 
The stabilized platform vertical accelerometer consists of a fluid-filled sphere. Over the years 
the fluid evaporates through the Perspex sphere. Check the fluid level at least once every three 
years. Experience has it that a small refill is required every three years. Section 5.4 will explain 
where to check and how to refill. 
As long as the sphere is correctly filled, the motion sensor is a robust sensor with nearly 
perfectly buoyant invulnerable mechanics in the fluid. However, with insufficient fluid inside 
the sphere, the mechanics in the fluid will no longer remain perfectly suspended and ultimately 
will collapse under its own load if deployed at sea. For a long life of your wave motion sensor 
carefully maintain the sensor fluid level. 
When in doubt, several tests in section 5.4 describe how to roughly verify the correct 
functioning of your motion sensors. 










