The steam launch hull can be almost any type hull, enough capacity to carry the weight of the boiler, engine, fuel, cargo and passengers. The aft should have enough room for a large propeller. The type of boiler has to be considered when selecting the hull design or vice versa. The vertical boiler lifts the center of gravity and the hull has to be stabile. The horizontal boiler lowers the center of gravity and stabilizes the hull, but it requires more room in a small boat.
If you want a classic steam launch you can make it your self or order it from a boat builder. You can find old steam launch plans at The Central Archives for Finnish Business Records (ELKA) in Mikkeli, Finland. You can find also plans for new building methods and materials. When using old plans and new materials you should be careful. For example when building an old steel hull design using strip planking, the hull is lighter than the original and it floats differently.
If you are lucky you can find an old steam launch hull rusting in the barn. Restoration of an old hull is usually more time consuming than building a new one. Beautifully renovated steam launch is a real jewel and you should not miss the opportunity if you find one.
Steam Launch plans
The Traditional Boatshop
Building Material and Methods
Traditionally the steam launch hulls were made of wood or steel. Strip planking and plywood epoxy are the most suitable of the new methods for DIY boat building.
Building a beautiful wooden hull requires a lot of skills and experience. If you are not sure of your competence, you should have a professional boat builder to do it.
Here you can find links to some Finnish wooden boat builders pages.
Steel is relatively low cost material and it is easy to process it. You can fix mistakes afterwards, so it is good material for do-it-yourself builders. You have to invest some money for the tools if you don't happen to have them before
Here you can find some steel boat projects:
Sami Venäläinen's steel boat project (only in Finnish, but lost of pics)
Roberts 434 steel sailing boat project
Plywood-epoxy method is the easiest way to build a boat. Making the hull itself doesn't require much skills or tools. Building the interior and finishing the boat requires some woodworking skills. When designing the hull or selecting the plans, you should remember, the plywood sheet bends only in one direction at the time. You should try to hide the needed edges under the water line.
Plywood-epoxy steam launch project:
With strip planking you can make round shapes, but it requires a bit more wood working skills than plywood-epoxy.
A Dutch steam launch project with strip planking:
The fiberglass is the most economic way when you are building several hulls, usually commercially or together whit your friends. You can also buy or sell the used molds.
A Swiss fiberglass steam launch project:
S/L Isle of Jura