a small receptacle, shaped like an inverted top hat, fitted to the tank top or a deck for the purpose of freeing that space of water without detriment to the completeness of the water tight inner bottom
Isitya esincinane esifakelwe kwitanki ephezulu okanye kumgangatho ngenjongo yokukhulula eso sithuba samanzi ngaphandle kokwenzakalisa ingqibelelo yokungangeni kwamanzi kumphantsi ongaphakathi.