It’s a moonless night the fog hanging low on the water as you navigate your way down the coast. Your running lights flare back at you from the fog. How do you keep from hitting “stuff” , stuff like freighters, fishing boats, rocks, or buoys. One of our readers Dennis, wanted to know.
Like driving a car, somethings you can control and others not. You never know for sure that a piece of plywood won’t fly out of the dump truck ahead or a rock will have rolled off the hillside just around the next bend. We drive anyway, we are used to the risk, basically most people don’t think about it.
Likewise with sailing. We can do pretty well with things that stick up above the water a few feet, especially if they are made of steel or rock. But things in the water are a little tough. Most offshore boaters would list whales and cargo containers as the biggest risks. The odds of hitting something like that are pretty low, but at night, we slow down a bit, following the boater’s adage, don’t approach something faster than you want to hit it… We hope the whales will look up from their cell phones and hear us coming… Oh wait that’s a human trait.
Radar is a device that sends out a beam of energy and then looks for that energy to be reflected from the objects that it hits. Our radar can probably “see” about 30 miles.
A newer device that we love is called AIS. AIS is a small box that boats carry that announces by radio what kind of ship it is, the name of the ship, how fast it’s moving and what it’s course is. These are now mandated for commercial shipping internationally. The thing we love is that it also calculates the CPA, closest point of approach, and TCPA time to closest point of approach. When you change course to avoid, you can see the numbers improve, even if the ship is not in sight.
We sit outside and watch a split screen. The left side has a chart which shows the depth, the buoys, rocks and other navigational challenges. The right shows the radar. When we know there are no rocks about, we zoom the chart out so it covers about 40 miles around the boat. The AIS triangles are on the chart so we can see the big ships moving. The radar portion is usually set to about six miles so we can see fishing boats and smaller objects close to us. Unfortunately fiberglass boats tend not to show up as well, but it’s what we have.
As we approach San Diego Bay, A stream of freighters are converging on the entrance. At 4 pm a small fishing boat, invisible to radar, throws on his search light as he passes…. No running lights. The radio squawks to life “This is Warship 6 located at 32 degrees 15 minutes north, 120 degrees 20 minutes west preparing to conduct live fire exercises, maintain a 50 mile distance from my ship.” In southern California there is a lot of military activity. We are about 4 miles out from the entrance buoy to San Diego harbor. I peer ahead through stabilized binoculars and see a dark shape in the channel, the silhouette of a navy destroyer, illuminated with the minimum of lights and NO AIS. Luckily this is not warship 6. Now, a stream of fishing boats are zooming out of the harbor into their familiar waters. We slow way down and wait 45 minutes for sunrise. As we enter the harbor three Navy tugs race out to greet an aircraft carrier.