Ships can appear suddenly
Action in Fog – Doug King – Boating Instructor – Boating Victoria
Fog can be one of the scariest situations at sea. With the time of year fast approaching where fog becomes a real possibility, it is a good time to discuss ways of navigating in fog and restricted visibility.
Fog is caused when water vapour condenses into tiny liquid water droplets in the air. It is particularly common over salt water due to the salt promoting condensation. The most common fogs this time of year are radiation fogs. These form when air is stable and relatively moist. The sky must be clear as well which causses heat loss by radiation. Light winds are also a requirement for the formation of radiation fogs.
Radiation fogs can be accurately predicted and normally “burn off” after the sun has risen but can be slow to dissipate over water. Advection And Sea Fogs can occur along the coast and pose the same challenges.
If possible, avoid fog by not going out on the water. If it is imperative that you make a trip or get caught out, sensible precautions and pre –planning will make it easier and safer.
Navigating in poor visibility can be stressful and dangerous. If you are inexperienced in restricted visibility it is easy to get lost or imagine that you are travelling in a direction that is different to reality.
Don’t forget that Restricted Visibility situations which includes Fog are defined as “heightened risk” If you are not already wearing a PFD on you must put one on.
There are a number of dangers in fog. They are –
This is probably the biggest danger particularly if you are operating in a busy area or in a Port area such as Port Phillip, Geelong, Westernport or Portland.
GPS is a great aid to knowing where you are but – high levels of skill are required for accurate navigation and they do not predict accurately where you might be in the future. Hazards appear suddenly out of the fog and it can be hard to assess the path of moving vessels.
- Getting Lost and Not Being Able To Locate Your Launching Position or Marina.
While GPS aids significantly in position fixing it is not acceptable as good seamanship to enter a Marina or narrow channel or river using GPS alone. Errors in placing waypoints, currents and tidal flow can all play a part in taking you off course sufficiently to have an incident that will spoil your day. Most boaties would have heard of people coming to grief by relying solely on their electronic aids.
There are a number of strategies that good boaties employ to deal with risks posed by fog and restricted visibility.
In all cases you should slow down to a safe speed and turn on your navigation lights. A safe speed is a speed which allows you take action to avoid a collision. In heavy fog you will most certainly be down to a walking pace. It is up to the skipper to determine visibility distances and set an appropriate speed.
To Minimise Risks of Collision.
- Sound a fog signal. On small boat underway the correct sound signal is one long blast every two minutes. Vessel under 12 metres may use any means to make sound signals. If you don’t have a horn, consider carrying a whistle on board for such occurrences.
- Post lookouts and keep a sharp lookout. Lookouts should also keep a keen ear out for other vessels sounding fog signals. It is a good practice to stop from time to time and shut down the engine to listen.
- Be aware on hearing another vessels fog signal that sound travels in varying ways through fog and the apparent direction of the signal or the intensity of the sound may not be what it seems.
- If you are in a port or approaches to a port, monitor the working channel for the Vessel Traffic System. In Port Phillip it is channel 12 VHF and Westernport - Channel 14. You will hear ships reporting positions and can use that information to build up a picture of large shipping traffic.
- If you are in a small boat, stay in water that is to shallow for large vessels.
- If necessary, find shallow water out of high traffic areas and drop the anchor. Wait until fog clears and continue your journey.
- You may be able to change your route and take a track that provides greater clearance from dangers such as reefs, shoals and headlands than you normally allow in clear conditions. That is – build in a greater safety margin.
- Use the GPS to set clearing distances from dangers and have the alarm set.
- Monitor depth and use a depth alarm to alert you when you start reaching shallow water. This can also help you fix position.
Avoid Getting Lost
- Good boaties will plan their trip in detail before leaving even if fog is not forecast. They also maintain situational awareness – they know where they are all the time and what compass course to steer home.
- If fog rolls in, fix your position immediately and re confirm a compass course to safety. Review your position and double check for dangers en route including the possibility of encountering other vessels.
- If you have radio contact with your local Volunteer Marine Rescue Group (VMR), radio your position and intentions to them.
Use your compass to steer a course. GPS units and plotters will have screens such as a “roadway” to guide you but they take your eye off a wider outlook. Compass steering allows you to maintain a steady course without your eyes being diverted constantly to a screen.
If you have planned your trip before heading out, getting home will be a little slower but won’t pose too many problems. If you haven’t planned you have put yourself under unnecessary pressure when fog rolls in having to plan “on the spot”.
Don’t rely solely on the GPS to solve your problems as they arise. It is easy to become confused or hit the wrong button. In fog, preparation is everything. But then preparation is good practice all the time.
Safe boating in fog or restricted visibility relies on seeing and being seen, hearing and being heard.
There are a number of legal requirements such as Sound Signals, safe speed and lighting requirements. These are only a re enforcement of good seamanship practice.
Put your PFD on, fix your position and radio your position to the local VMR.
A good tip if travelling with other vessels is to have the lead vessel trail a life ring or other suitable floating object on a light line behind them. This object creates a wake that others can follow at a safe distance.
Practice steering a compass course in good weather and it will be easier in fog. At the very least know the compass course back to your base before you leave.
Remember, the one good thing about fog is that at this time of the year, it generally means a fine sunny calm day once it has lifted.
This article is general information only. It should not be viewed as operational instructions or as a substitute for proper training.