I'm usually the sole coffee drinker onboard. I've found the Italian Mocha pot is a great design for a boat. I use a small Bialetti my son gave me. I got hooked on a smaller, stronger cup of coffee while traveling in Italy. Not a true Espresso maker, a Moka pot brews coffee 2 to 3 times stronger than drip.
For the boat, it has a very low center of gravity so it doesn't tip or move around the stove top. There is no filter to use, all you need is ground coffee. It takes little fuel as the boiler section is small and designed for a small flame. And it's easy to clean and of course, unbreakable stainless steel.
Fresh water goes in the bottom chamber, ground coffee goes in a basket that fits on top. The main body is screwed onto the bottom.
The difference in how coffee is brewed is right here: Once the bottom chamber begins to boil gently (low heat, again), it is forced up into a pipe and then through the ground coffee. Once through the coffee and screen, the quickly brewed coffee is forced up another pipe and empty's through the top (brown foam flowing center - photo), into the upper chamber, which holds the brewed coffee.