Introduction: Metal Steam Powered Boat

About: Diving headfirst into metalworking. Mostly just making tools to make more tools, occasionally ending up with a finished product along the way. check out what i have been building on my instagram over at http…

In this instructable we will be making a metal boat powered by a simple form of a steam engine.

there are two main components to this build the powerplant and the hull. both involve permanently joining metal together from soldering, and welding.

here is a basic overview of the two processes used to fabricate this boat.

the powerplant consist of a burner and a boiler. both will be made out of various copper and brass parts that are soldered together. soldering involves heating up the base metal until the solder turns to liquid and flows over the clean base metal. As the solder flows it fills the tiny gap between the two(or more) pieces of base metal. you need to input heat so the solder flows but not too much heat otherwise the solder alloys can mix into the base metal causing the base metal itself to melt. Due to the heat involved with the steam engine I choose to use hard silver solder because it melts and flows at a much higher temperature than tin/lead electronic solder. Hard silver solder is 75% silver, it melts at 1,365°F (741°C) and flows at 1,450°F (788°C) compared to 60-40 tin-lead solder which melts around 370°F (188°C). that being said you will need a more powerful torch to sustain the soldering operation. you could use the tin-lead solder if you do not have access to an oxy-acetylene torch. you just have to be more careful with operating the burner for long times as you risk the chance of melting the solder that holds the burner airtight rendering your burner useless.

the other main component of this boat is the welded steel hull. Welding involves joining the two metal pieces together by melting the base metal pieces into themselves... often times but not always by adding an additional piece of metal similar in composition (filler rod) into the molten base metal puddle. there are hundreds of different ways to weld some of the more common ways are in a forge, using a torch, or with electricity and shielding gas. for the task at hand i choose the TIG welding process, it involves shooting an arc of electricity off the end of a tungsten electrode. unlike other forms of welding this process is very clean and controllable which comes in handy when welding such thin steel pieces together.

Step 1: Tools and Suplies

hand tools

  • ruler
  • file
  • metal shear/ tin snips
  • saw
  • marker
  • paper
  • scissors

soldering tools

  • torch
  • flux
  • hard silver solder
  • pickle

welding tools

  • tig welder
  • gloves
  • welding helmet

metal forming tools

  • various metal pieces as stakes: pipe, roofing nail
  • vise
  • anvil
  • cross peen raising hammer
  • dead blow hammer
  • ball peen hammer


  • copper or brass tube
  • copper sheet 20ga
  • copper sheet 29ga
  • cold rolled steel 24ga

Step 2: Step Two: Power Plant

a simple steam motor with zero moving parts is the perfect power plant for this project. a burner heats up a boiler filled with water turning it to steam providing more than enough power to propel the ship forward. these simple steam engines are often called pop pop motors

for the boiler you will be using a technique called raising. you will need a hammer and a stake. you can use anything as a stake here I have a random piece of stainless steel scrap that I softened the edges on with a file. you will also need to soften the copper otherwise it will work harden and tear. soften the metal using a process called annealing. to anneal non ferrous you simply heat it up until it is glowing red then let it cool.

the boiler consist of a forged pan with two inlet/outlet pipes soldered to the bottom side and a thinner piece of copper sheet soldered to the top

  1. take the 3/32 tube and cut it into two pieces about 5 inches long
  2. on the 3/16 thick pieces of steel (I found a thick nail) sharpen one end to a point
  3. flare out one side of both tubes over the 3/16 thick nail tool
  4. anneal the tubes put a bend about 90degrees with the flared out end being on the one inch leg and the straight leg on the unflared leg.
  5. to start cut out a square piece of 24ga copper and anneal it with the torch.
  6. the forming technique we will use is called "raising" hammer the 24 ga copper over a thick piece of metal called a stake. you will need to strike the copper on the unsupported area right above where it makes contact with the stake. go around all the edges and you will notice it is much harder than when you started.
  7. its time to anneal the metal again once to soften it and make it pliable again
  8. do another round of raising taking care not to tear the copper at the corners. it okay if you do you can fill it in with solder later when you put the lid on the pan
  9. once you have the pan forged sand the top mostly flat with files.
  10. lay a sheet of sand paper abrasive side up on a hard flat surface and rub the top edge of the pan on it to create a totally flat surfac
  11. drill two holes in the bottom of the forged pan the same size as the tube you are using.
  12. place the bent tube into the hole so the flared ends holds the pipe into the pan.
  13. solder the tube into the pan. first put flux onto the joint area then give it some heat with the torch to melt the flux. once it is a sticky white paste place a chip of solder or melt a glob of wire solder into the fluxed joint. at this point let the metal cool a little and apply more flux to the joint to be sure that you cover the solder. add more heat with the torch. remember to heat the metal where you want the solder to flow to and not the solder.
  14. using the .010 inch copper as the top. place the top of the motor onto the forged pan and solder it on in the same manor as the tubes. trim off extra that is unneeded

alcohol Burner

  1. using the 5/8th inch thick copper tube cut off a piece about one inch
  2. anneal it
  3. start raising the copper into the shape of burner over a piece of thick steel pipe or rod slighty smaller then the inner diameter of the copper pipe.
  4. anneal it again when it hard and finish raising untill it looks like picture
  5. solder on a long piece of copper scrap to act as a bottom and a handle.
  6. cut up a piece of cotton (I used a pillowcase) about 1/2in by 3 inch as a wick. stuff most of it into the hole at the top of the burner, fill with alcohol and test it out.

Step 3: Step 3: Steel Hull

for the steel hull i found some scrap 24ga cold rolled steel. i decided to use this metal because it is very thin keeping the weight of the ship fairly low making it more efficient for the motor to propel the ship. the hull is fabricated out of two identical side pieces and one bottom piece.

  1. draw a similar shape of the brown paper bag on the anvil in the picture. this will be your template for the two sides of the ship
  2. trace around the paper template with the marker using magnets to securely hold the paper template on top of the steel sheet
  3. cut out the side pieces with the shear or snips. the edges of the steel will have sharp burs on them so use caution when handling.
  4. debur all sharp edges with file or sandpaper
  5. line up the two pieces on top of each other. i held them together with magnets again so they wouldn't move around while i went around the edges with a file to make sure that they are identical sizes.
  6. remove the magnets and lay the pieces ontop of eachother
  7. tack weld the two pieces together at tip of the ships bow.
  8. carefully align the pieces together making sure everything lines up. if its not ok cut or pry the two pieces apart and redo the tackweld. iff it is ok add another tack weld near the bottom of the ships bow near the keel.
  9. put a couple tack welds between the two welds even spaces apart
  10. completely weld the two sides of the boat together at the bow
  11. spread open the sandwiched layers into a ship shape.
  12. form the stern end of the ship over a metal pipe with hammer and by hand to give it a nice round shape. clamp the two ends together and tack weld it together.
  13. put butt weld between the two pieces
  14. form the sides into a shape that resembles a ship using the hammers or by hand.
  15. lay the shaped hull design over the piece of metal and trace the shape of the hull onto the metal. this will be the bottom of the hull. be sure to leave a little extra room around the hull by offsetting the distance with the marker.
  16. cut out and deburr the bottom of the ships hull
  17. find the center line of the hull and draw a line down it. this will be a reference line to help line everything up.
  18. give the bottom of the hull a slight V along the center line. you can do this by holding the metal over the edge of a hard surface with one half hanging off the edge. strike the floating side evenly with a happer to define the vee and use your hand to even it out . i used anvil however you could use anything with a hard straight surface like the edge of a table or a flat thick piece of metal.
  19. this next step is easy but can take some time and attention to detail. you need to fine trim the bottom piece to fit the shape of the hull. you will have to give the metal a slight curve up in the front so it fills in the gap at the bow. you will also have to give the metal a rounded curve up for the stern.
  20. you are ready now to start tack welding the hull together. start at the bow and work your way down to the stern adjusting the metal as you go. you will want to place the tack welds a few inches apart. take your time doing this as it will make for a nice looking hull. once everything is lined up nicely you can go back and put a tack weld in between the previous tack welds. ideally you want a tack weld every inch that way when you are welding the two pieces together it wont pull apart as the thin metal warps.
  21. after tack welding you can start the welding of the ship. if you put too much heat into the ship it will warp. For example if you started at the bow and ran a weld all the way down one side it will warp as the molten metal cools and hardens. to combat this you want to do a lot of little welds all over so the heat is evenly distributed into the ship. You will want to keep the welds fairly small 3/4 to one inch in size. be sure to jump around put a weld at the left side front then opposite side. that way the metal can push and pull against itself evenly distributing the shrinking forces.

installing the motor is simple drill two holes in the botom of the hull and stick the copper tubes throu it. solder the pipes into the steel hull to create a watertight joint

  1. DECK - flip boat over on sheet of steel, scribe a line ontothe steel along the side of the hull as a guide. stop about 1/2 way down the hull this will be the bow deck after you cut it out.
  2. tack weld the bow deck section to the hull. start at the tip of the bow and work your way down
  3. start to fabricate the stern deck as the same way as the bow deck. befor you weld it in cut out a section for access to the boiler. it should look like a horsehoe shape about 1/2in thick.
  4. CABIN - using the cut out part of the rear deck snip out two triangles as seen in the picture.
  5. in the same mannor as the bottom of the hull bend it over a hard edge such as anvil using hammer into the classic cabinshape. cut out a strip the same hieght. hammer it around a pipe to create the curve
  6. tack and weld it together.
  7. UPPERDECK. pick a style and size for the upper deck and draw it out on paper cut it out and transfer it to the metal. i use magnets to hold it while tracing. cut out and debur with sandpaper
  8. cut out a strip about 3/4 the height ot the cabin. shape it around a pipe to match the shape of the upper deck.
  9. tack and weld it to the bottomside of the upperdeck.
  10. sand down all edges of the hull cabin and upperdeck
  11. tack weld the cabin to the upperdeck.
  12. SMOKESTACK. using the same copper pipe as the burner cut off a piece about three inches.
  13. I decided to solder the copper pipe onto the steel upperdeck using the tig welder instead of the torch. for this i used a sillicon bronze brazing rod. it works the same as tigwelding with the steel fillerrod the only difference is that you dont melt the base metal just the fillerrod. you are going to need to aim the torch more at the copper pipe for two reasons because the copper a)dissipates heat very quickly and b) is much thicker than the thin steel.
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