Advice needed please,

I have now decided I want shore power on my new cat. Pretty dumb not to order it in the first place! I plan to install a 16 Amp galvanic blocker. I don't know what Seawind normally do to make a 240V ground on 1000 XL2. I assume the only metal in the water would be the rudder shafts as the outboards will be tilted out.

So, is a 240 Volt ground usually installed? Where is it located and how is it fitted?