Do not count on being seen - see them, if you think they will get close call them on VHF. Ocean swell and sea clutter will hide most small vessels from Radar until you are close. That is if it is on and if they are watching it.

I like my new to me AIS receiver for that reason. The odds of being hit by a small boat without AIS in insignificant. It is the big boys that you have to worry about. They have underpaid, overworked crews that are often asleep at their watch stations, especially on ocean passages where they do not expect to see anyone.

A couple of stories:

I have asked ships how well I show up on Radar and got the reply: wait, I will warm it up and let you know. In these days of every cent saved goes to the bottom line mentality, big ship radar maintenance is based on usage - don't run it and save on maintenance costs.

I was in the Darwin-Ambon race over a decade ago and had to pass a safety inspection. I didn't want to buy a reflector and the safety officer said "go to a bar, Get an aluminized mylar wine bag from box wine and hang it from your flag halyard". It actually works as good as most reflectors. I ran tests with another boat raising and lowering a bag.