Sail Through Engineering Pre-Workshop Activity Thank you for your interest in our Sail Through Engineering workshop. This pre-workshop activity is available to help your students get the most out of their upcoming visit to the MIT Museum. The activity will provide context for the workshop as well as review important skills that students will be using. Materials Sail Through Engineering pre-activity worksheet: one per student Pencils Objectives Students will be able to visualize the relationship between a three-dimensional object and two-dimensional cross-sections of that object. Students will be able to use an offset tool to measure cross-sections of a boat hull. Students will be able to describe MIT alumnus Nathanael Herreshoff s process for designing and building boats. Activity A. Introduce the Sail Through Engineering workshop Explain to students that they will be attending the Sail Through Engineering workshop at the MIT Museum. During this workshop, they will learn about the engineering design process by building and testing their own model boat hulls. They will use modern technologies, such as CAD (computer-assisted design) and laser cutting, as well as exploring methods that MIT alumnus Nathanael Herreshoff used to design and build over 2,000 boats, including five America s Cup winning yachts. This activity will help students to practice the skills needed for the workshop. B. Pass out one worksheet to each student. They can work in pairs to go through the questions. An answer key is provided below. C. If the students are curious about how boats play a part in MIT research today, this article on how MIT researchers are designing 3D-printed, driverless boats for ease of transport and self-assembly can be helpful: http://news.mit.edu/2018/fleet-autonomous-boatsservice-cities-reducing-road-traffic-0523 1
Sail Through Engineering Introduction Nathanael Greene Herreshoff is a graduate of the Massachusetts Institute of Technology (MIT) who was born in 1848 in Bristol, Rhode Island. He graduated from MIT in 1870 with a degree in mechanical engineering, and went on to become a successful naval architect. He was an innovative designer who designed over 2000 boats, including sailboats and steam-powered ships. Five of his boats even won the America s Cup! Over 14,000 artifacts related to Herreshoff are archived in the MIT Museum s Hart Nautical Collections, which you can access online: https://mitmuseum.mit.edu/explore/collections. You are going to design a boat in this workshop, just like boat builders such as Herreshoff did, beginning by carving a model of half of the boat s hull. A hull is the main body of a ship, including the bottom, sides, and deck. Since these models were hand-carved, you might Hull imagine how it would be nearly impossible to make both sides symmetrical. This is why boat builders only created one half of the hull and took and measurements from this half. These measurements are called offsets. The measurements were then used to create full size slices of the hull, which served as molds for the wood that would be used to form the hull of the boat. You can use an apple to practice visualizing the slices that make up a three-dimensional (3D) object. Pretend that the apple pictured in the top row of the chart is the hull of a boat. The vertical lines are the positions at which offset measurements are taken. The second row shows what each cross-section (mold) would look like. Look at the relationship between the slices from a 3D object (side view) and how that slice looks like in two dimensions (2D) from the front. 2
1. Now try the same exercise with a real boat, the Robin, which Herreshoff designed in 1895. Three different views are provided to help you to visualize the 3D shape of the boat. Apply the idea of 2D slices that make up a 3D object to the Robin s boat hull and draw the cross-sections at the three labeled locations. A B C 3
2. Which of the following two-dimensional cross-sections (A, B, or C) could have come from this diagram? A. B. C. 3. Look at the image of a wooden half-hull model below. Which of the following boats, A, B, or C, is most likely based on this half-hull model? 4
4. Herreshoff used an instrument called an offset tool to measure points along his half-hull models with high precision. He used the offset tool to measure both the height of a point on the boat hull and how far that point is from the center of the boat. Use the offset tool below to determine the coordinates of the current point on the boat s hull. The arrows indicate from where to read each measurement. A. Horizontal X: Vertical Y: B. Horizontal X: Vertical Y: Offset Tool Boat Half-Hull 5. You may have noticed that the boat in question #4 is upside-down. Why do you think half-hull boat models were measured, and built, in this position? 6. When measuring offsets, a boat designer has to choose how many measurements to take for one cross-section. List one advantage and one disadvantage of taking 20 measurements per cross-section compared to only 4 measurements per cross-section. 5
Answer Key 1. 2. C 3. C 4A. X=1.75cm Y=4.5cm 4B. X=3.25cm Y=2.75cm 5. The deck (top) of a boat is usually a wide flat surface which is stable for the boat to rest on. The bottom of the boat tends to be narrower so the boat would need more supports on the sides in over to keep it from falling over while being built. 6. 20 measurements will give a much more accurate final result as smaller features, such as curves, will be measured. 4 measurements, although it misses many features on the hull, requires much less time to measure. 6