The best option for a NDB Antenna on Offshore installations is a long and vertical Longwire. The problem is, however, limited space to install such antenna.

Exept limited space for the antenna, the condition for NDB radiation from offshore locations is optimal.  This as the offshore installation is a solid low impedance resistor to ground (sea), and that radiation over sea provides much longer coverage than over land.

We can supply you with:

A 20 m Wire Antenna Kit has shown to be suitable for frequencies from approx. 350 kHz and up.  For frequencies below approx 350 kHz a longer Antenna is needed.

Whip/Mast antennas type AS1R and AT80B manufactured by COMROD in Norway is widely used for offshore / ship installation where it is difficult to install Longwire

For purchase of such antennas we propose that you purchase these Antennas directly from COMROD. https://www.comrod.com/wp-content/uploads/AS1-R.pdf