True David, there is a very big difference with the way RF works, from the High frequency end of MW, to the Low frequency end - it seems to be something, the "Experts" often forget all about, when relating received signal strength to transmitted power

Radio 390 proved that in the 1960s - with their highly effective signal, of probably less than 10kw - from Red Sands sea fort.

In theory, the Sky wave is less at low frequencies, though 648, seems to come in pretty well in Western Scotland most evenings. Even with 2kw

At sea, on a ship, it would be tricky to create something similar to the Omni-directional at Orford - though the Mi amigo's cast iron mast, was a similar height. But not really very suitable for frequencies less than 963.

With many fewer MW transmitters, MW DXing - could become more interesting in the future at night.