VHF antenna mounts and Electrolysis

[Robbie.g]

i mostly use 'pacific' antenna's, they're isolated from the mast due to the stepped washer that seperates the antenna from the s'steel bracket, [if you put it the right way round!!!]
Very interesting about the keel issue.... never thought about it....will now.... is there any reason/advantage to not having the antenna isolated from the mast??