Stability measurements on rubble-mound breakwaters

This paper describes methods and equipment for testing the stability of rubble-mound breakwaters. One instrument, called the OBDS (Optical Break-Down Sensor), is intended for global evaluation of the break-down process as a function of time. A second instrument, called the BCOM (Blink Comparator), is for observing and measuring the break-down process in detail. The instruments have been tested and found to give reliable results in the laboratory. Suggestions for improvement are made and it is believed that these will increase the usefulness and make this new technique applicable in the field.