Fog - During periods of reduced visibility, the navigator's work is more difficult. At sea you can't make celestial observations. Even when the fog is so shallow that celestial bodies are visible, the horizon is not available as a reference. Unless the vessel is approaching, land, there is no cause for concern regarding navigation only danger being in a collision with other vessels.
The safety of your ship requires reliable position information. Along a coast where the shoaling is gradual, the echo sounder can be of assistance indicating the distance off.
The decision of whether to enter a fogbound harbor should be made carefully.
Once committed to the channel, the vessel may have no alternative but to continue on to anchorage or the wharf, for some areas there is not room to turn back, and anchoring is unsafe. It is sometimes wiser to stand off or anchor for a few hours than to risk grounding or collision.
If the decision is made to enter the proximity of danger and the currents make it necessary the maintain a good position at all times. Fog limits the number of objects that can be used for fixing your position.
During periods of reduced visibility the practice of steering exact courses, with changes at definite points, is a must in pilot waters. If the fog is dense,this requires careful steering and attention to all details, such as current, changes of wind, etc. If a single buoy is missed, consideration should be given to anchoring and waiting for improved visibility.
With the possible exception of radar, the most important navigational aid during in pilot waters is the echo sounder or hand lead. Continuous soundings, compared it to
the chart, can provide information on the position and safety of your ship. During fog one should keep a sharp lookout for any objects that might appear in thin places in the fog. It is well to have a lookout stationed forward on the the bow.
The lookouts and all persons on the bridge should listen for fog signals.
As soon as a signal is heard, an effort should be made to identify it and determine its bearing. Remember that at reduced speed the relative effect of current is greater.
