"I hadn't noticed those before, but by zooming in and out, it seems that they appear when you are zoomed out so that ship icons overlap - the number indicates the number of vessels in that area. If you zoom in, you will see the grey…"
"I feed data for Vancouver BC to both Shipfinder and MarineTraffic. I find that MarineTraffic's display is 5 minutes or more behind my local display - don't know the reason, but I think I've seen that some…"
"If your vessels are equipped with AIS transponders, you should be able to see them in Puget Sound and the Strait of Georgia. Shipfinder does show some spotty coverage north of Georgia Strait, but none in Alaska. Marinetraffic.com shows vessels…"