Just Run Over the Little Guys

Steve Dashew has a good post on selective-use AIS features. I have ranted on this before, but features that allow you to ignore Class B, small vessel AIS signals continue to accumulate. AIS works in a range that largely intersects the coverage of radar and visual monitoring. Since both radar and visual monitoring can usually detect large vessels, small vessel detection is one of the main benefits of AIS.

There seems to be a widespread notion among mariners that class B signals will create too much noise and clutter on displays, so it needs to be turned off. I have even seen this attitude among single handers sailing small craft.

Large carriers have great difficulty seeing small boats because they are so high off the water. At a distance, small boats do not show up against larger waves. Up close, small boats may fall in the visual shadow of the ship. On radar, a small craft may appear to be sea clutter. Class B AIS is the most effective method of avoiding the rundown of small vessels by large carriers. Please don't turn it off.