Your 2nd mate calls you at 2 o clock night and vis is poor quesion leading to rule 19

1
FOLLOW

1.switch on the other radar, start fog signal, call for additional lookout, inform engine room to be standby for reducing speed if required.
2. assess the prevailing condition i.e
a. distance from land
b. trarffic density including concentration of fishing vessels
c. state of sea/weather
d. proximity of navigational hazards on the planned route.
e. depth of water available.
f.make assessment of visibility using radar
3. if the conditions are unfavourable, then
a.speed should be reduced to maneuvring and vessel preferably on hand steering.
b.radar to be on short range (3nm/6nm)
c.effect bridge/engine room manning as per company's sms i.e doubling of watches and operating on non UMS mode.
d.engines ready for immediate maneuvring.
e. position plotting frequency to be increased
f. more than one methods of plotting position