Sensor system for pressure measuring over a sail : Construction and implementation of a sail pressure measuring system

Abstract: Wallenius Marine, KTH and SSPA are working together on a wind powered car carrier, that will ship cars over the atlatic. KTH has a small scale prototype of this vessel, and uses this prototype to test performance and new sensor systems, that can be used on the full scale vessel. The KTH research group wanted to add a sensor system that measured the pressure on the sails of the prototype ship. This thesis is about the design, construction and implementation of this sensor system. The system was first designed. The pressure measuring system would be divided into blocks where one block would measure one part of the sail. Each block would be connected to a common communication bus. This bus was then connected to the current control system of the ship. The pressure was going to be measured through pressure taps in the sail. After the design was done, the construction began. Here the choice of components was made. The sensors were from Honeywell, the microcontroller was a Teensy 4.1, communication was done using a RS-422 transceiver from Digilent and the power components were a 24 to 3.3V regulator and a 24 to 5V regulator. A circuit board was designed and created to fit all the components. The system was tested in a wind tunnel to verify that it worked as it should. The next step was the implementation. Three segments of the sail surface was removed. A support structure and fittings was added to the removed parts, so that they can be removed and attached. The taps was added and the system blocks were fitted. The measuring system was tested on the ship out on the sea. The results were that the system was able to measure the pressure distribution over the sail surface. The resulting measurements matched what was expected from viewing the tell tales on the sail. The system worked as specified, but more testing is required to see how the measurements are affected by factors such as the other sails and the hull. This system will continue to be used by the KTH research team in their future research projects.