What two modern day ways of signaling SOS distress while sailing?

#1: If at night, by use of a searchlight to send Morse Code. A regular flashlight will only work if you are in front of a very DARK background.

#2: Day or night: Radio Morse code.

#3: Daytime: Signal flags along your forestay or backstay.

#4: Daytime: Semaphore flag signalling.

#5: Day, or night with searchlight shining on it: Hang your country flag upside-down. This is the internationally-recognized sign of distress.