Here one idea on how NDB arrival to port could be implemented. The key would be to install NDB's at visually distinctable objects, so you can visually confirm that you have sailed to the correct NDB.
In this example there are 4 NDB on 2 light byos and 2 light houses. Larmor Plage "castle" is simply useful as visual reference, even in limited visibility.
I have modded the TWOS Lorient harbor chart to illustrate this example. I hope that the original creator does not mind.
Accurate timing is the only way to measure range. NAV1 -> NAV2 switchover as the nearest NDB can be used to conjfirm that you have completed a leg or are half way.