Thanks!
The boat is about 40 feet but I hope to feed all the data from the boat in one place close to the main board.
I have solar panels. But they don't deliver enough power during the winter. That's why I also like to have an update of the voltage of the four 75Ah batteries so that I can charge the batteries from land (220V) when needed.

I intend to buy a starter kit and a sensor which can catch up a leak in the boat and send a warning text message to my cellphone.
When it works I plan to add functions like, boat temperature, and voltage level of the batteries.
Has anyone already done this? I'm very new to the Arduino. Can I please have some tip of what hardware to buy for this?