200808 Navigation in restricted visibility
Official Report Source: USCG Safety Alert HMRMS 04-07
A ship strikes a highway bridge, causing damage to the fender system and a 53,000-gallon oil spill. A barge strikes a US Navy facility, causing extensive damage. Two tugs, one pushing a loaded gasoline barge, collide, narrowly avoiding a disaster. What do these recent marine casualties have in common? All the vessels were navigating in restricted visibility.
Although the investigation of these incidents is ongoing, they provide an opportunity to remind mariners of the hazards of navigation in restricted visibility and the procedures required to do so safely.
Of course, the best way to avoid an accident in restricted visibility is not to get underway, or to seek a safe haven if conditions change while underway. But that is not always practical, so every vessel must be well prepared for navigation in restricted visibility every time the vessel gets underway. Companies should adopt written policies emphasising that a delay to the vessel is preferable to the undesirable consequences of an accident. Those policies should place the responsibility for sailing a vessel with the vesselÅfs master, and prohibit interference or second-guessing by shoreside managers.
If a vessel must navigate in restricted visibility certain procedures must be followed:
* Sound fog signals: Fog signals are required when navigating in or near an area of restricted visibility.
* Reduce speed. The state of visibility is one of the most important factors in determining safe speed. Speed should be reduced - to bare steerage if necessary. Slowing the vessel reduces the likelihood of a casualty because it gives more time for the operator to assess the situation, and keeps power in reserve if emergency manoeuvres become necessary.
* Post lookouts. Additional lookouts must be posted, at least one as far forward as safely possible. Lookouts should be well rested, have no other duties, and receive periodic training on proper lookout procedures. Lookouts should be relieved regularly to ensure they remain alert. At a minimum, a lookout should have binoculars and a means of communicating with the bridge. Most importantly, lookouts should wear a personal floatation device and non-slip shoes.
* Take frequent position fixes. Too often mariners fail to appreciate the importance of frequent fixes while navigating in restricted visibility. Over-reliance on radar and electronic navigation systems can cause a mariner to lose situational awareness, in part because of time delays while the image is refreshed. A vessel can travel several hundred yards, especially if the operator fails to reduce speed, in the time it takes for the track line to update on an electronic chart. In some cases it may be necessary to take fixes as often as every three minutes.
* Monitor other vessels. The bearing, range and closest point of approach (CPA) of other vessels should be closely monitored. Communications should be established early to determine the intentions of other vessels. Short and long range scanning by radar should be used to identify targets before they get too close.
* Summon help to the bridge. A one-person watch cannot safely navigate in restricted visibility. One person cannot man the helm, monitor the radar, serve as lookout, plot fixes, communicate with other vessels and the bow lookout, and so on. And finally:
* Train, train, train. Most well-managed vessels conduct regular fire, abandon ship, and man overboard drills, but very few practice restricted visibility procedures. Every vessel should have a written restricted visibility procedure and hold regular training. This training should include practising taking and plotting fixes by all methods available, in case of a failure of one of the position fixing devices occurs.
FEEDBACK - November 2008
Low visibility is seldom a factor for not sailing. Most professional mariners sail their vessels in all parts of the world safely and in dense marine traffic lanes and with full appraisal of current situation. However, when vessels are in regulated navigable waters controlled by a VTS, mariners expect professional advice from them. As part of a port system, a VTS must also ensure that the pilotage and VTS services are manned by professionals and that aids to navigation are reliable. In very adverse conditions, instead of issuing a mere advisory to vessels that does not really assist the master in decision-making, a more positive 'no movement' order will ensure greater safety.