Surfing above the sea : development of a hybrid hydrofoil

Abstract

Interest in hydrofoils has been increasing in popularity in recent years as a means of high speed and efficient mode of transportation across waters. However, the physics of hydrofoils is not well understood and past research did not focus on the design of hydrofoils.

The potential gain in efficiency when hydrofoils are operated at high speeds is well known. However, current motor-driven hydrofoils are powered by internal combustion engines like most other marine crafts. To further increase efficiency, a hybrid propulsion system can be used. The field of hybrid propulsion is also garnering attention in recent times, with much research conducted about how fuel consumption can be reduced in a bid to cut greenhouse gases and slow down the rate of consumption of non-renewable energy.

This objective of this project is to design, build and test a hydrofoil to evaluate its performance for use with a hybrid engine. In this phase, a fully electric propulsion was used due to safety concerns of testing the hybrid engine, but the weight of a hybrid engine was emulated. Data from this experiment provided insight into the amount of thrust required which would aid in sizing the hybrid engine.

The results from this experiment also provided more insight into the complexity of hydrofoil theory, especially the estimation of drag forces. Although full foil-borne operation was observed, the prototype experienced significantly more drag than predicted. There were many assumptions made and testing the validity of the assumptions is required.

Deeper research into the physics of hydrofoils is necessary, and the prototype built for this project can be used as a platform for future research and experimentation.