Engineering Design Report: Optimised Steam Powered Speed Boat

This report presents the results of an optimised steam powered speed boat which was built by students. They were required to work in groups of two to achieve this. This prototype was tested multiple times. For the first test, the boat was tested without the engine (floating capabilities) and the second test involved an engine which was the heating the coiled copper with flame. The heating of coiled copper wire was essential for the speed of the boat. The higher the fire flame, the faster the speed. The testing was done in a 4 m through and it took the boat 32 seconds to cover the distance.

Introduction

Boats are water transports which are mostly explained by their floating. They are mostly said to be a small vessel for traveling over water, propelled by oars, sail or an engine. Even when boats are a source of transport, their functions vary a lot depending on their size and designs. The design of a boat has an impact on the speed and the floating of the boat.

Background

For a boat to sail successfully it must have a centre of mass. Also, for a boat to sail and speed up, the structure of the hull must be carefully taken into consideration as the boat has to cut through the water. Density is an important property in many material used in engineering application and so it is with the boat. For a boat to float, the density of the material used to design the boat must be less than the density of the water the boat is floating on. For a boat to float successfully, the buoyant force must be greater than the gravitational force and this is by the Archimedes’ principle. For speeds boat the Flat-bottom hull is the best option as they skim across the smooth water of lakes and rivers to achieve maximum speed. For boats to keep sailing for a longer time, they need some power to the thrust for lift and forward movement. If a boat is not balanced or it does not have a centre of mass, then it will sink or tumble over one side.

Steam Powered Speed Boat (SPSB) is a simple self-made plane which requires basic engineering design technics for which the flame from a candle is used as a source of energy to heat the coiled copper tube to boil the water inside it. When the flame is sufficient to boil the water inside the coil, the hot water will make the copper tube hot and it will create the difference in pressure. The hot pressure inside the pipe takes in cold water from where the boats is sailing and exits the hot water from the pipe. The difference in pressure from the hot pipe to the water causes a pop-pop sound which causes the boat to accelerate faster.

Design and Methodology

In building the boat, students decided to recycle waste materials instead of buying a boat or fancy material. Styrofoam, foil, cans and milk carton were collected as they are light in weight. These materials can float hence they were used to build the prototypes. The first prototype was made of Styrofoam and foil as they are light in weight. Cans were used to build the second prototype and milk cartons were used to build the last prototype. The engine used for the first two designs mentioned was the same, which was the coiled copper tube and a tea candle. For the last design (3rd), several changes were made which included the engine changes. For the last prototype a milk carton was used as the body of the boat and cans to make a boiler.

The design of a new boiler introduced a boat with two engines, the first engine was the coiled copper tube as it was a constraint and the second one was the boiler made of cans with straws as the pipes to take water in and out as per pressure difference. The pipes of both engines where placed below the boat. Student realised that as the design has two engines, it also needed a bigger flame. A decision was taken to optimise the tea light candle by melting the provided wax into pieces of cardboard and used that to produce more flame. Pattex Epoxy glue was used to merge the pieces in designing the boat and making sure that there is no water linkage in the boat and boiler.

Testing

In testing the operation of the SPSB students were given a specific testing area which consisted of troughs of 4ʺ in width, 2ʺ in depth and 177ʺ in length. The testing site was susceptible to wind and that might affect the results and jeopardize the idea of the project. The recording of the time started immediately when the students lit the candle or source of flame. The first time to be recorded was the time it took the engine to start pop popping and then the time the boat took to reach the finishing line which was at a distance of 4 m.

Results

Since the students ended up with three different prototypes of the speedboat, all boats were tested for performance focusing on the pop pop time and time taken to reach the end of 4 m. The first boat made of Styrofoam performed well and reached the end within 1. 5 minutes. Because of the flame this design melted. The second design made of cans also floated well but it lacked a balance and had no hull to cut through the water. The last design made of milk carton floated and moved fast enough to reach the end with less than 40 seconds having a pop pop time of less than 10 seconds when tested 3 times in different troughs. The best time recorded from this project testing was 32 seconds for 4 m.

For a boat prototype to move, the energy conversion from chemical energy to heat energy to sound energy and them kinetic energy happened successfully. The heat from the tea light candle supplied approximately 2242. 5 watts of power. The thrust force of the boat supplied 1. 729 watts of power to the boat as water was being heated up. Efficiency of the testing was 0. 078 %. The mass of the prototype used was approximately 70 g with water in the pipes.

Recommendations

During testing of the SPSB prototype, it was observed that the boat was not moving directly straight and it was experiencing friction, which reduced the speed. For the boat to move straight a rudder should be attached at the back and a centreboard in the middle. To increase the efficiency of the SPSB a bigger flame and bigger boiler can be used.

Conclusion

The SPSB prototype was tested and it was concluded that speed depended on the amount of flame produced by the candle. The mass and centre of mass of the boat was also a factor. The more mass the boat had, the more it sank. For the boat to float at all times, buoyant force must be kept equal with weight.