Question 1: do I really need the combination fishfinder sonar to replace my DS? These seem nice but I don't care about fish. Stupid sub-question: does a GPS chartplotter display the chart's theoretical depth with sonar or do I have to have the dual frequency fishfinder sonar to display the depth?
No you don't need it...Chartplotter displays the CHART...depths are from the last survey...not necessarily related to current reality...but mostly!
Question 2: What is the advantage of horizontal vrs. vertical chart orientation? The Furuno and Garmin have vertical orientation whereas the others are all horizontal (which seems better to me).
I agree with CD...I like Vertical and a track up orientation.
Question 3: Radar seems like a nice-to-have feature to me, whereas others would say it is more important than GPS in the cold waters on New England. How much more does the extra radar gear cost for the Furuno/Si-Tex/Northstar add (I couldn't get a straight answer out of the guys at Boston Boat Show)?
Radar is kinda necessary for offshore or fog work...a chartplotter is all you need if you don't do either of those....but radar is always nice to have. Adding the Garmin 18 to the new Garmin Plotters will set you back LESS than a grand.
Question 4: What is in a brand name in terms of reliability and service? I've heard great things about Raymarine's service, questionable things about Northstar, and I have no experience with Si-Tex or Furuno. Garmin is a mixed bag in my experience.
Northstar is high end and quite expensive. I think Raymarines service really sucks. Pretend you own a radar and are having a problem...now try to speak to someone about it!! They do make good products though! I would recommend Garmin for what you need.
Question 5: Do these units get ripped off when the boat is at mooring? Should I install it so that it can be stowed away during the week? YES
Question 6: Is an external antenna necessary? The boat has a bimini that isn’t used much. Most of the units require an external antenna and I am assuming that I'd replace the Loran antenna with a GPS one. NO external is not required.
Question 7: How do you install the associated electrical, antenna, sonar, and radar cabling? Does it go through the pedestal or into the deck near the pedestal? Should I have a professional do this?
(It will be snaked up through the pedastal...get EVERYHING at the same time and let a pro do it while you "help" so you know where to find everything! )