Furuno FELCOM 250 - Manual (Page 16)

1. HOW TO INSTALL THE UNIT
10
9. Coat all bolts and nuts with silicone sealant to prevent electrolytic corrosion as shown below.
Note: The cable entry hole ( φ60) at the bottom of the antenna functions as ventilation hole,
allowing trapped moisture to escape the dome. For that reason, ensure the hole is not
blocked.
Nut
Silicone sealant
Silicone sealant
Spring washer
Flat washer
Antenna fixing bolt