It does depend
If I sailed in Florida, I might find it slightly more difficult to justify the radar...maybe. But I sail in San Francisco Bay where fog is common and vessel traffic and currents are even more common. The question came from New York, where I presume conditions might be similar.I have been in severe fog (barely see the front of the boat) just once without radar. That was enough to justify the expense. Where I sail, waiting out the fog is not really much of an option. If the current doesn't take you somewhere you do not want to go, then perhaps a radar equipped and fast moving ship constrained by draft will off you by surprise. If your radar reflector made you large enough you will have the additional pleasure of hearing the five blasts of his horn, but perhaps not knowing exactly which direction to go.GPS can sure help keep you out of the deep water channels, so maybe you get run down by something a little smaller instead, the ferries don't take much draft. It also can keep you off the rocks. So, I would spend the money on that before a fishfinder. In a low vis situation, I'm not really interested in where the fish are, ok maybe the whales.My order is something like this for electronics and safety. VHF, backup VHF, radar, depth sounder, gps. It may seem odd to put the gps last, but frankly, if you think about the worst situations you can be in the order makes sense.Communication is critical, so two. Radar will keep you off the rocks and let you know what is out there, particularly big stuff. It also can tell you where you are when in proximity to things you want to not hit. So in the critical situations, it is multipurpose. Gps will keep you off the rocks, but does nothing to identify that large ship moving towards you.Besides fog (very low visibility) we also get conditions offshore, and even in shore, where visibilities might be significantly reduced for several days. I've sailed a few miles off the coast all day long without seeing land. So conditions are important, as are your options when those conditions occur.I think a good test is to sail out into your nomal sailing area, then close your eyes and imagine that all you get to see is the compass. Feel comfortable? Got Radar? That's what it felt like to me caught in that fog. I knew how to navigate, knew how to ded recon my way out of it, and I did. But it was very uncomfortable not knowing what else was going on around me.The radar went on our new 290 prior to the mast hitting the deck on delivery.Dan Jonas (S/V Feije)