Already in 2005 a Swiss team managed to cross the Atlantic with a solar driven motoryacht. There were techical ups and downs, but the engineers on board continuously managed to get everyting fixed.
Now, two decades later, a cruising yacht that is primarily driven on solar, crossed the Atlantic. Or, could do it for 2/3. Still there was about 5 ton of diesel necessary to feed the generator.
The energy consumption of such a big yacht is serious. Especially if one would maintain a high speed. The additional fuel needed has been a rough 5 tonnes of diesel (5500 liter).
But it s a great start. Better than using another 10 tons, which would be necessary for a motor yacht with a general speed of 6 knots.
There is still to winn. A suggestions to cut this last 5 ton down to (near) zero: fly a kite sail. This works night and day, and the speed of the boat can make the props start running to regenerate electricity to the battery bank. Or, perhapsa ‘nouveauté in a time that everything must be bigger, one could take a smaller yacht?