The question is what instruments are needed and what are not. IMHO the wind isn't. Why? Cause it's easily discernable. Who really cares if it's 17 kts or 16.5 kts? You can easily see and feel that know what's happening. I don't have clock that tells me when sunset is either. LOL

However, yes you could calculate closest point of approach, speed with some bearins and if you know the height of the vessel you might get close to how far away he is. However; to my knowledge, no matter how good the hair on the back of your neck you won't know the name of the vessel should you need to contact them, nor the MMSI. Both of those are valuable pieces of info.

That said, I'm not suggesting you give up anything. I don't have all the bells and whistles aboard. I've personally known 3 boats here (S of the hurricane belt) that have been hit by lightening - two in the last year; and both had so much instrumentation that it took them 6 months to get it all sorted out and back on the water. That and even with insurance a nice bucket of money. Without all that electrical gear hanging around no matter what happens my life should be much easier. And before anyone say's anything, on non of the boats was there any damage to any laptops, those plugged in or not. And no laptops were stored in the oven.

Go Slow
Sail Far
Stay Long