On page 55 of the report, these interesting obserations: "The R&DC project team believes that it is well within reach (considering current off the shelf and
developmental devices) to manufacture a signal device as described. As a matter of example, this report
includes an Appendix C that discusses battery requirements for an LED Visual Distress Signal Device.
The characteristic for the “electric S-O-S distress light” defined in 46 CFR 161.013 is inadequate. During
laboratory pilot testing, the project team almost immediately realized the shortcomings associated with
prolonged eclipses (“off time”) between letters and SOSs. The project team performed multiple iterations on
the SOS signal before achieving a flash pattern that achieved a reasonable level of conspicuity. "

It is almost impossible to buy a flashlight that does not have some sort of 'flash,' 'strobe", or "beacon" function. Some evaluation of these products would be useful. Most that I have seen are monochromatic - white. They are probably way better than nothing, but probably not as effective as the goold old signal mirror...