Walt C,
I have been using radar since I got my boat in 2006-7. it runs if the boat is running, not dependent on the visibility condition. That is done for 2 reasons, one, if you have it, according to my understanding of the ColRegs, it is considered a navigation aid and thus should be deployed,; and two, it sees all around me even when I don't -- ie it watches my back while I am looking forward.
I have been in fog, various times, and variable densities. Believe me, it is not always light. I left Stuart Island one time, planning on some whale watch time, and the weather was reported patchy fog. It was, from a 2-3 mile visibility down to a Really 2-3 feet. There was a time I could not see the water from the window at the helm seat. At That point, I was relying fully on 2 GPS screens, and radar. I was hearing a BIG foghorn, and thanks to the Radar and AIS was able to talk to a container freighter heading down Harro who reported that he had not seen the bow of his ship for a couple of hours. He was traveling at a reduce speed of 12 knots. He could see me on his AIS and radar. (Wheeuu!!!) BTW, I never saw the Orca.
On another occasion, I was out to photograph the Canoe Journey canoes as they pass between Protection Island and Travis Spit, in the fog. (Makes for some neat pictures.) Visibility was about 150 feet and fairly steady. As I am watching 2 canoes and a support vessel about a half mile away, on the radar, approaching in the fog, I notice another blip, approaching from my stbd beam at a fairly rapid rate. It is lined up almost directly towards me, coming from 3 o'clock. I turned 90 to stbd, and then another 25 and it is now about 1/4 mile and still closing fast. As it went by me, now on my port bow, it is an aluminum boat about 20 feet, with a single person sitting at the wheel, head down, and apparently watching his GPS track. He sat up pretty straight when my canned air horn woke him to my presence. BTW, my fog horn had been cycling every 2 minutes as required. I credit my radar for avoiding a very possible BAD situation.
As to the radar watching my back, I have had a Washington State ferry sneak up behind me, and the rather huge BLIP closing from behind, alerted me to the ferry coming through the pass between Shaw and Crane Islands. The visibility was clear, but that 20 knot cruise they do sneaks pretty fast when I'm doing 6 knots.
The note to be sure and include an AIS receive VHF is a very good plan due to the multiple advantages of AIS info on you screen. That is discussed in many other places on this forum.
Harvey
SleepyC :moon
