Once took a can of the Nescafe self heating coffee on a winter round of golf and it wasn't too disgusting. Don't think you can get the stuff now, so it was either, a) a crap seller or, b) highly toxic. Now discovered a clever little device called a thermos flask, holds more drink and you can screw the lid on to save some for later. What a fascinating modern world we live in!
I tried one that was sold in Waitrose, called Java or something like that. Tasted vile and you only got a mouthful. They seem to have stopped selling them now.
Tesco sell them, someone told me the coffee drink called rocket (or something )kept you awake I drove from UK to Venice after drinking four of them. Tasted awfull, I fell asleep but my eyes kept open, weird, never again.
ones on a trip once. They tasted OK but didn't get very warm. I was told they get warmer if they're kept flat while heating. That's tricky on a yacht. They were pretty expensive to.
I use thermos flasks. A good trick on a small boat is to always put the remaining water from a kettle into a thermos, after you make a brew. A drop of warm water is always handy for the washing up or washing yourself. Even if it's not hot enough to make a drink.
Apparently one can purchase vacuum flasks made from indestructible stainless steel, inside and out. Perfect for a boat, no glass to break. Modern wonders never cease.