Having the majority of the ballast concentrated in one place midships is guaranteed to create a very unnatural and toy like ‘bobbing’ motion as the model goes through small waves. It is far more effective to split the ballast up and have around a third at each end and the battery, motors and electronics should generally make up the third in the midships area.
This 1/48th scale corvette required 6kg of ballast so I put 2kg of lead shot into the bow, encased in resin, and 2kg of lead shot in the stern. It looks so much more realistic to see it cutting through the waves rather than bouncing over them.
The lighting looks spot on Alasdair.