8
6 Limitations
Our study is subject to limitations, which we particularly emphasize here and should be taken into
account for interpreting this study and for future research.
For validating purposes, the described phenomena were observed multiple times. Nevertheless, the
total number of observations to date is still too small for robust statistical based evidence.
To determine the detection range, the distance between the position of the detected PIL and the
observing ship was used. The positions of the ships and PIL-platforms were determined using GPSbased
AIS data. The respective AIS transmission intervals, in combination with the fundamental GPS
inaccuracy, led to small deviations in the determined distances. A dynamic measurement procedure
was used where observers approached free floating test objects at a constant speed. With a relatively
stationary PIL platform and ships moving steadily, the small distance inaccuracies are negligible
compared to the detection range differences between the LED and incandescent bulb. This has no
effect on the observed detection range.
Test objects anchored to the seabed might create changes in the wave pattern (e.g. spray, foaming)
around the test object. To avoid these artificial effects this study completely relies on free floating test
objects, which is also as realistic as possible as people in life jackets are commonly also free floating
but also leads to increasing deviations in the arrangement of the test setup.
7 Acknowledgement
Parts of this measurement campaign were carried out as part of the research and development project
SmartShip and funded by the Center for Digitalization and Technology Research of the German Armed
Forces (dtec.bw) and the European Union, NextGenerationEU, under grant no. UT7007.
References
[1] IMO, ‘INTERNATIONAL LIFE-SAVING APPLIANCE (LSA) CODE’. International Maritime
Organization, 1996.
[2] IALA, ‘MARINE SIGNAL LIGHTS - CALCULATION, DEFINITION AND NOTATION OF LUMINOUS
RANGE’. International Association of Lighthouse Authorities (IALA), 2017.
[3] IMO, ‘REVISED RECOMMENDATION ON TESTING OF LIFE-SAVING APPLIANCES’. International
Maritime Organization, 1998.
[4] CIE 070, The Measurement of Absolute Luminous Intensity Distributions. Commission
Internationale de l’Eclairage Vienna (Austria), 1987.
[5] IALA, ‘MARINE SIGNAL LIGHTS - DETERMINATION AND CALCULATION OF EFFECTIVE INTENSITY’.
International Association of Lighthouse Authorities (IALA), 2022.
[6] C. A. Douglas, ‘Computation of the effective intensity of flashing lights’, National Bureau of
Standards, Gaithersburg, MD, NBS report ; 4554, 1956. doi: 10.6028/NBS.RPT.4554.
[7] Y. Ohno and D. Couzin, ‘Modified Allard Method for Effective Intensity of Flashing Lights’, Aug.
2002. [Online]. Available: https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=841689
[8] W. E. K. Middleton, Vision through the atmosphere. University of Toronto Press, 1952.
[9] T. Fang, Y.-G. Kim, I. Gong, S. Park, and A.-Y. Kim, ‘Development of performance measures based
on visibility for effective placement of aids to navigation’, International Journal of Naval
Architecture and Ocean Engineering, vol. 7, Sep. 2015, doi: 10.1515/ijnaoe-2015-0045.
[10] BIPM, ‘Principles governing photometry’. Bureau International des Poids et Mesures, 2019.
