There are few ways, though, as gentle and serene as the warmth of a candle.
Step 1: What you Need.
My Clubbers used foil pie-tins as the hulls of the boats, kitchen foil as the sails and tea-lights to provide the heat.
We have, in the past, had success with normal-sized candles trimmed to only half an inch in height, or small clusters of birthday candles.
Step 2: Construction
A certain amount of intuition is also desirable.
Tear a piece of the foil to a suitable size, and fix it to the side of the pie-tin by scrunching the edge of the foil along the lip of the tray.
Curve the sail over the top of the boat. If it droops too far, add a crease or curve along the middle of the sail to ~~stop it drooping~~ add structural integrity.
Stand the candle in the boat, and you're ready to go.
The photos in this step are of the fire boats made by my Science-clubbers, before they took to the water. Some required tweaking, but they all worked to some degree.
Step 3: The Circular Fire Boat.
This effect can be used on purpose as well - setting up two candles and sails facing in opposite directions on a circular metal lid created a boat that spun on the spot.
The clubbers had the idea that the idea could be used to make decorations which floated and spun in garden ponds or pools during a barbecue or garden party - the shiny foil sails would cast changing reflections around as the boats spun.