Making a pop-pop boat is utterly simple. I first learned the concept from my Wolf Cub Scout book, in a project called a 'Jet Boat'. According to the archivist at Boy Scout headquarters, the Cub Scout book contained this project from 1954 through 1977. John de Treville found a plan in a Cub Scouting handbook dated 1948. Two generations of Scouts, raised on pop-pop boats!
All you have to do to make one is wind a piece of small-diameter copper tubing into a coil, and stick it into something with a boat-like shape. (Derek Pratt's article in Model Engineer showed boats made from oval herring tins.) Put a flame under the coil, and you have a pop-pop boat. To run the boat, fill the tube with water and light the flame. Soon, the tube will get hot enough to boil the water, and you'll hear it make the characteristic pup-pup-pup sound that gave the boats their name.

The Pop-pop Pages, in conjunction with Steam in the Garden magazine, is pleased to present an advanced construction article in which Marc Horovitz gives detailed instructions on how to build your own metal pop-pop boat.

In the meantime, you can make a simple 'jet' boat out of balsa or pine, based on the Cub Scout Handbook design. I made mine from balsa, and later covered it in aluminum flashing tape from a home-improvement store for water-proofing. I used two pieces of 1/4 inch (6mm) thick balsa. From the top piece, I cut out the inside of the hull with a scroll saw. I glued the two pieces together with waterproof wood glue, cut the point of the bow on the saw, and then drilled the tube holes at an angle in the back transom of the boat.

The tube is 1/8 inch (3mm) diameter copper, widely available in hobby and auto parts stores. I wound the tube with two turns around a 1 inch (25mm) dowel. (Pulling on the tubing while bending may help prevent crimping.)

For a burner, I took a rectangular piece of brass sheet, cut square pieces out of the corners, and folded the sides up to make a shallow tray. I soldered the joints between the sides to keep the fuel from leaking out. (Use silver solder or 2% silver-bearing solder. The 2% can still be worked with an ordinary soldering gun, and may be found in electronics supply stores.) A tray of this type is suitable for burning sterno jelly or the Esbit tablets sold for toy steam engines (both are alcohol-based). Candles do not appear to work with this design; they simply don't put out enough heat.

To build a boat with a diaphragm-type boiler, get a copy of Model Engineer magazine, 5 January 1996. In it you will find Derek Pratt's excellent article on building these boats from herring tins and other preformed metal parts. (For example, The pop-out lid from a cocoa tin, or similar, is used for the body of the boiler.)


Or, have a look at this excellent web page: Slater Harrison's Science Toys. The author, a teacher whose students have built hundreds of these boats, has developed a very simple and unique design. His boats can be made with almost no metal parts. Definitely check this one out!


John Woodson, at the other extreme, made his own metal-forming tools to produce a small run of these gorgeous models of the famous '40s racing boat Miss England. (Click on the photo to see more at Woodson's web site.) His boat features twin keels w/integrated rudders, high-efficiency exhaust nozzles, functioning condenser/solid state bilge pump, and an improved burner. Not to mention the hand-made mahogany storage box.