Spanish to English Tech/Engineering Ships, Sailing, Maritime

Any idea what this is supposed to mean? This is from a general checklist of things that a boat owner has to do related to anchoring and mooring, i.e. not anchoring itself, just ensuring that the boat is "ship shape" and ready to do mooring and/or anchoring operations when the need arises.

Spanish (Spain) to UK English

Grilletes del fondeo are mooring/anchoring shackles.

Grilletes del fondeo roscados a tope

Here's the section
EQUIPO DE FONDEO Y AMARRE
 Ancla y cadena conformes al plano de fondeo
 Cadena firme a la estructura y ancla asegurada en posición recogida
 Grilletes del fondeo roscados a tope
 Disponga al menos de dos estachas de amarre
 Inspeccione visualmente las estachas para comprobar desgaste o rozaduras
 Un par de defensas para amarre