Piloting in Limited Visibiliy

The Golden Gate is one of the most challenging and dangerous harbors in the world. This is caused by a number of factors: winds, swift currents, rocks and shoals, wave action, fog and ship traffic. This essay will deal with the dangers of ship traffic and strategies to ensure a safe passage. The Golden Gate has been an important shipping port after the first Spanish ship sailed in. It is now the port of call for container ships, tankers, grain carriers, scrap steel carriers, barges, cruise ships and naval vessels – to name a few. As such, the port is a 24 hour, seven day a week affair with no real “commute” time. Ships come and go at all times with some times of very little traffic to times of ships lined up one after another – sometimes even passing each other. To make matters more complicated the Golden Gate is often enshrouded by fog reducing visibility to mere feet. Take huge, hard to maneuver ships and then limit the visibility and you have a recipe for a collision.


It can easily be argued that radar is the most important navigational tool since the lighthouse – possible even since the compass. While for decades radar was something only ships and expensive yachts had, radar has become both affordable and small. Good units can be had for around $1000. However, often boats will have radar but the skipper either does not know how to operate it properly or interpret its information. This is where practice is key. Use your radar on clear days and look around. See what the screen tells you and then match what you see visually with what is on your screen. Adjust the tune and gain to maximize your targets without getting false echoes. Learn to know what a real target looks like as compared to a false echo. Almost all modern radars have a “wake” function that puts a lighter shade on the screen where the target was previously. This function can help greatly to determine whether a target is a potential collision threat or not. Remember that targets that are a threat are ones that have their wakes pointed away from you. Note that this is “relative” movement and do not get it confused with movement over steady ground. Take a look at the radar screen below. Assume that you are going forward at 10 knots. Which target should be of most concern to you? Many say the one on the upper right because it looks as if it is going to cross our path. Yes, will. However, it will be far in front of us when it does. That target is actually ahead of us doing a slightly faster speed and on a course more to port than ours. The target that is on the left is the threat because the wake points away from us so it is on a constant bearing relative to us and its range is decreasing.

If your radar doesn’t have a wake function you can use a grease pencil or dry erase marker to track the targets. It is not as easy as a wake function but this is how it was often done before the wake function. Another tip for proper radar operation to change the range often from approx ! mile to 6 miles or more and back down – always knowing what range you are on. Small targets that are nearby can get lost in the clutter at a larger range yet ship traffic is speedy and a larger range and the time to make avoidance maneuvers is needed. Now it is time for the real test. Take along a reliable first mate to be your look out. Cover your windshield or pull the bill of your hat down low so you can only view your radar. Now navigate to a buoy a few miles away and back with your first mate as a safety look out. Practice makes perfect. MARPA MARPA stands for (Mini Automatic Radar Plotting Aid). This is a great tool for collision avoidance and is available on most higher end radar units. The radar takes information from the GPS and can track up to 10 targets giving course speed and time of collision if a course or speed change is not made. However, MARPA is not perfect and since unlike a true ARPA system that gets position, speed and course via radio signals from the other ship MARPA has to calculate this. As Terry Tifft sometime about the oil rig we clocked at five and a half knots off Pt Conception one night! It eventually got a better read and slowed it down to a half knot of less – and that error is to be expected. GPS Like radar the GPS and the GPS/Chartplotter is a wonder of modern navigation. The GPS will tell you exactly where you are and which way you have to go (in a straight line, of course) to get to your next location. However, it does not tell you if there is a ship bearing down on you or another boat in your path. It is a great tool to let you know where you are but is by no means a substitute for radar. Shipping Lanes The shipping lanes both in and outside the Gate are well marked on the NOAA charts. Outside the Gate the lanes are quite simple and logical. Shipping traffic leaving the bay crosses the bar through the “Main Ship Channel.” Once across the bar the pilot boat will come alongside and take their pilot off and the ship will go to sea via three routes depending on its destination. If it is going north the ship will turn right towards “N” buoy leaving the buoy on their port side. If the ship is intending to go west then it will head west-southwest towards “W” buoy leaving that buoy to port. Finally, if the boat’s destination is to the south then the ship will turn to the south towards the “S” buoy – again leaving the buoy to port. The area between the S, W, and N buoy and the western end of the Main Ship Channel is known as the precautionary area and is an area where ship may go in any direction. As such, it is important to be very aware of traffic while transiting this area. From each traffic buoy to the “reporting area” there is a shipping lane – the Southern in the south, the Western in the west and the Northern in the north. The inbound and the outbound lanes are separated by a one mile buffer zone. Vessels must report when they enter the reporting area. The vessel traffic reporting area is a radius of 38.7 miles from Mt. Talmapias. From the south it is approximately off Pigeon Point, to the west it is past the Farallon Islands and to the north it is approximately off of Pt. Reyes. If a ship is beyond this area there is no formal traffic scheme and the ships can go just about anyway they choose. When a ship enters the precautionary area the ship will begin to slow somewhat and the pilot boat will rendezvous with the ship so a pilot may come aboard. The ship will then proceed towards the gate. The same will happen in reverse for ships leaving the gate. It is important to know that the pilot boat is always on station between the main ship channel and the SF approach buoy (often called the lightbucket) since in limited visibility you can expect to see a target either drifting in this area or running to a ship in it.

Inside the bay there are also shipping lanes in the main bay and towards the south bay, the Oakland terminals and through San Pablo Bay but as the ships move to different docks, wharves and anchorages the traffic may not stay in the lanes. In the main or central bay there are three lanes – one along the city front and another north of Alcatraz. The deepwater channel runs south of Angel Island and that then passes above Harding Rock before heading towards the Gate. In all but the deepest draft vessels, the southern lane along the city is used for inbound traffic while the northern one is used for outbound. Deep draft vessels will use the deep-water lane as it is deeper and both inbound and outbound ships will use it.

Vessel Traffic Service

After the collision of two Standard Oil tankers in the bay in 1971 one foggy night the Vessel Traffic Service was established to avoid another such disaster. VTS uses radar and a control room much like an air traffic control scheme. Ships must report when they enter the reporting area and they are then tracked until they are docked or leave the reporting area. Although VTS is tracking them at no time will VTS take navigational control like an air traffic controller. They can and will give recommendations. However, at one time they would take navigational control if asked. But in 1980 they took control of the charter fishing vessel Dora Bella which was lost in the fog but the vessel went aground at Baker Beach. Since that time it has been the rule that VTS will not take navigational control. They will only give you what traffic is in your area and may make recommendations. You are still completely responsible for your safe navigation. VTS gives a traffic report every 30 minutes at the quarter past and quarter to the hour (i.e. 8:15 and 8:45) on channel 12 in the offshore area and channel 14 inside. The VTS controller will give the ship name, course, speed and time the ship will arrive at a location (i.e. the SF sea buoy, Pt. Reyes, etc). It is wise to have a piece of paper handy to write down this information – including the ship name – since the read it off very quickly. If you are quickly entering or passing through and area of possible ship traffic you may contact VTS on the appropriate channel (12 or 14 depending on your location) and ask for a traffic report for your area. Note that they will not give you advice as to whether or not you should cross at a certain time or other navigation decisions. This responsibility is yours and yours alone. They will only give you the reported traffic and its’ reported movements. Contacting Ships While in the VTS control areas, ships are asked to use channel 13 for ship-to-ship communication. It is perfectly appropriate to contact a ship on channel 13 (or 16 for that matter if 13 does not work but then switch to 13) to discuss crossing or passing maneuvers and strategies. This is where writing down the name of the ship from the traffic report comes in quite handy. If for some reason you cannot contact the ship you can contact VTS on channel 12 or 14 (again, location dependent) to help you contact the ship. It is important to note that proper VHF radio etiquette and terminology will get you a long way here.

As fishermen we often have a channel that the fishermen can talk. However, the law requires that you monitor channel 16 while underway. This can be done with one radio with “dual watch.” But before and when transiting an established shipping area it is only prudent to monitor 12 or 14 to listen to both the scheduled traffic reports and the communications of VTS with the ships in the area. A second radio is needed to do this effectively but they are now inexpensive and small in size.

On Fishing Luhrs we monitor 16 on one radio and have the other radio tuned to the channel we talk with other fishermen with. As we approach the shipping lanes we turn one of the radios to channel 12 to get the reports and we do this until we are clear of the shipping lanes. It has come in very handy. See this website for more info on VTS: http://www.uscg.mil/d11/vtssf/ Tug and Barges One of the most common vessels in the shipping lanes is a tug with a barge. If you see two or more targets close together and moving quite slowly assume that you are seeing a tug towing a barge. Although these vessels move very slowly (5 knots is not unusual) you need to be aware as to not cross between the tug and the barge. The cable is often just below the surface and can come clear or the water slicing your boat in half in the process like a wire cheese slicer. Equipment Failure – What to Do Electronics do fail – plain and simple. And since we rely on them to navigate on a daily basis we often have either not learned or are rusty on the way mariners navigated for centuries. Charts We get so dependent on our chartplotters that boats that have charts aboard are often a rarity. One reason is that the charts are often large and most small vessels do not have the space to easily roll one out. However, Bay and Delta Yachtsman publishes a rather handy chart book with most of the charts you would need for Northern California and the paper is water resistant. It is a great solution to the problem and you can find them at most West Marine stores. Compass Do you use yours? Is it accurate? The compass has been used for centuries and it is one of your most important navigational tools. A good compass can be quite accurate if set up and calibrated properly. Its is also important to routinely navigate via the compass in good weather and get used to how the compass rose reacts to changes in course and sea conditions. In general, a larger compass is easier to read and will swing more predictably. Depth Sounder Taking depth reading is probably the oldest method of navigation along with the sun and stars. However, unlike years ago, you don’t need to heave a lead line (although this may be needed if all of your electronics were to fail). With a chart, a compass and a depth reading one can follow the bottom contours. It is not terribly accurate by a long shot but if all else fails it is your best bet to make safe harbor.

Aids to Navigation Many aids to navigation have sound and or light signals and each one has its unique pattern. This pattern and sound is noted on your chart.

Sound signals Power vessels underway in fog or other limited visibility are required to sound a horn signal of one long blast every two minutes. Many loud hailers and some VHFs have this capability where it done automatically freeing the crew of this duty. Also, note that if another vessel is encountered in limited visibility and you are unsure of their course and speed and it is a possible collision situation five long blasts of the horn should be given. This signal means, “I am unsure of your intentions or course.”


Since we live in an area that has many days and nights of thick fog it is almost impossible to avoid it. I have talked with many boaters who say they won’t buy radar because they “don’t need it because I only go if it is nice.” Well, given enough time on the water they will eventually get caught in a limited visibility situation and they will unprepared.