Precautions 1

The first thing to do when you notice approaching fog is to plot an accurate fix on the chart as soon as possible. If for any reason you cannot get an accurate fix, then rely on your Dead Reckoning or Estimated Position.
Start sounding your foghorn.
Sailing vessels must sound one prolonged blast plus two short blasts every two minutes.
Turn on your navigation lights.
Rig up the radar reflector as high as possible if one is not permanently fitted. Remember, the big ships are more likely to maintain their speed, relying on their radar to detect other ships.
If the sea is rough, they probably won’t detect you, since the echoes from the waves cover the small echo from your sailing boat
Make sure that all crew wear their life jackets and that the life raft is clear and ready to use.
In addition, have some red and white flares handy.