I think that you are correct that the most likely problem with a PC based system is the hard drive. I worked with lots of PCs for a shore based company and hard drive failures seemed to be the most common cause of PC death, with fans a distant second, and power supply problems a way distant third. I'm talking about fatal problems, many times you could fix things by just wiggling a board or a cord back into place. On a boat you have additional problems of vibration, corrosion, and dirty power. My laptop seems to be relatively immune to those issues, but I use it rarely as a backup to my C-Map based Raymarine system. Note that as machines approach the five year mark the onboard backup battery tends to die. This can cause all sorts of strange behavior that is fairly easy to take care of on shore (if you know what to look for), but could be a major problem at sea. I would make sure that my backup PC boots before a major trip, don't just assume that it will work after sitting in a locker for three years. Many machines (especially laptops) use specialized batteries, and some are soldered in. Laptops are a bit fragile, I have lost the screen on two of them due to hinge failures (one caused by a misplaced foot.) I would make sure that any laptop was well secured to resist Bay..., uh, "Big boat" wakes. My Raymarine dedicated chartplotter has been a fair performer (touch wood). I have had a few issues; the main one is that it is far more sensitive to voltage levels than I would expect marine hardware to be. The SeaTalk network stops working (with the message "Seatalk Failed") after a day at anchor, and this has been since the boat and batteries were new. I was tearing what hair I have left out until my wife noticed that most instruments came back on as soon as we started the boat. We had a bad wire in the autopilot remote which also caused random "Seatalk failed" messages; the combination of the two issues caused me to hunt gremlins for a long time. Now for some reason, my RayNav GPS became less and less able to pick up signals; after messing with the antenna a lot I gave up and bought their new RayStar GPS. I haven't found the Raymarine software to be any more or less buggy than PC based software; I notice that they do a hard reset when they crash rather than print an error message. This can make you think that it is a hardware problem until you reproduce the behavior (I was a programmer so I am pretty alert to bugs and how to reproduce the steps that cause them.) I would insist that any PC navigation system be completely clean; use another computer for downloading games or connecting to the internet. I consider this issue a wash; it is fairly easy (less than 10 curse units) to update Raymarine's software when necessary. The biggest issue with dedicated systems is that you are locked into that year's hardware technology; my expensive RL-80 is pretty close to obsolete after five years! Meanwhile, I'm still using my five-year-old computer navigation software which I just transferred to my new laptop. I have had no problems with my C-Map chips, although they can be damaged by static electricity in theory. My biggest fear is that I will lose one because they are pretty small for something that is so expensive and critical. Newer systems use even smaller chips just to make life difficult for us aging boomers. Fortunately the super-wide coverage means that I rarely have to swap them out anymore. Everything is changing in the charting world with NOAA releasing their charts for free, on disadvantage of the dedicated chartplotters is that they do not (as yet) take advantage of these new (S-57) charts. For a laptop you only need a small travel inverter that can plug into your 12V outlet. For towers, you can get 12V and 24V power supplies which are used in car based PC systems. It is also possible to get solid state disk drives that use the CF cards that you probably use for your digital camera. They do not store as much as hard drives, but should have enough for the operating system and charting software. If you do it right, the only moving parts will be the fans. I'm thinking of making a system like this for my next boat -- although I will also have dedicated hardware like Furuno or Simrad. I'd bet that the fishing captains in Nova Scotia don't consider electronic (or paper!) charts to be essential. After a few decades you get to know where all the rocks are. The young guys just follow the others. Us explorers in fragile and expensive toys need to be more obsessed. George