A transformer is designed to change voltage and regulate the voltage coming in. The newer transformers do that, they just have advanced from 1960s technology and now also protect the circuit from spikes and voltage drops and other things with modern technology. Just about any transformer that is made for yachts over the past 10 years is now an isolation transformer which protects the yachts electric from stray currents, voltage spikes and whatnot and not the typical extinct transformers that you're talking about with just copper windings and a magnetic field. Mastervolt, charles, and all other well manufactured yacht transformers are isolation transformers which help prevent yacht electrical fires. Any modern marine isolation transformer will do what Orthokevin asked. The transformer I referenced is also a boosting transformer and will boost the current, so yes it is not a typical transformer in the sense of the word as it boosts the voltage when needed as well. But it is still a transformer none the less, although technically called a boosting transformer. Just like battery chargers. The new ones are ignition protected, have electronics with much better charging profiles for the various battery types, they also have several charging modes to help the batteries last longer. But, they are still a battery charger.