I agree with 'otn' on all points.

I'll just comment on my watch keeping methods.. On my last boat I had the
Furuno 1721 (crt) on a swivel mount that let me swing it from it's normal
chart table location out into the companion way.. I could see it from the
wheel.. On my present boat I have a Furuno 1720 that is fixed mounted at the
chart table but when I sit in the companion way I can see the display fairly
well. If I need to switch ranges or take a bearing, I'm only a single step
from my companion way seat (autopilot does most of my steering but I remain
in the cockpit/companionway). So, bottom line on display location, is where
you can see or access it while in your normal watch/lookout position. Don't
rely on any alarms zone 'bells or whistles'.. I have had too many boat enter
my alarm zones without these systems catching them (mostly when a vessel is
over taking me).

Something else to consider when you equip your boat with radar.. In the
event you are involved in a disputed accident, the boat with radar will be
held to a higher degree of responsibilty and the operater is expected to
know how to use his radar to observe other vessels manouvers, calculate CPA,
etc. (I can't quote Chapter and Verse, but that is what I was taught.)

Steve
s/v Good Intentions