@Matias Saibene Maybe you should lower the mesh a bit more, so that the waterline is at least at null, not at extreme low tide. So much of the collar should usually not be visible unless the
Blanke Hans* is about to become really angry with us.
The line labelled "N.N." in the drawings is the "standard null" used at that time (Mean sea Level in Amsterdam), which should be accurate enough (far away from the coast, there can be up to a 59cm difference to the reference geoid today)
* Northern German name for the North Sea, especially during storm. Originally it meant something similar to "Ne'er-do-well".