This is the killer question. As much as my answer : nothing !
I explain. In coastal navigation, frankly there's no point to anything. The computer does not contribute to security, does little more easily than standard GPS, does not save time. If we compare the time required to report the GPS fix on a chart (I do not mean to report dead reckoning) time lost in front of computer screen to tweak a lot of unnecessary functions, we soon realize that the computer board is a millstone round the neck.
Just the time spent in selecting material, understanding connections, solving power problems, install everything, make it working, and resolving the inexpected failures, one would spend the best time to hook some nice fish and invade the kitchen corner of the boat !
I already feel you shrug and think :
"He's not that guy well.,
it is the hospital that mocks Charity ! "
Not at all, I am simply lucid.
I address this note to those who consider themselves as "zero IT" and sometimes kind enough to ask me and ask me for advice. To them I say that the computer on board a yacht – pleasure, I specify – is not inevitable ! The pleasure of sailing is necessary for the maximum simplification of navigation. It has much to do with all that is above the bridge, rigging, sails, winches, windlass, blocks, rails, and so on, not to still be complicated life below deck.
Some nautical charts and guides, a rugged GPS that gives you your position without flinching at any time, and keep the fun and security without the technical problems. What about weather, you could say ? Honestly, 95% boaters sailing in summer along the coast, the weather is available every morning in the harbour house, three times a day with radio VHF, and even on our mobile phones. No computer required !
See Icon of the boat moving in real time on a chart displayed on a computer screen is a luxury. I mean it's the luxury of sailors who have nothing else to do – once again I only talk about yachtsmen, not mariners who have other imperatives – their days. I talk here to those fortunate 5% remaining boaters who sail "full-time", whether retired, sabbatical, annuitants or high seas runners. This category, I' unfortunately were only too rare moments, has ample time to equip a computer onboard that can give him all facilities for sailing offshore.
… and benefits
Actually it is in the context of offshore sailing that it makes sense. If you can afford, why deprive ? There is time available to devote to its implementation. It will get weather forecasts for the world, it will provide a global charting unobtrusive, prediction of tides and / or tidal streams to the world, and will provide to regularly send news, and also pictures, his family to reassure them. You will even be able to get the opportunity to write your adventures, create a blog to the attention of friends, and whatnot.
On the other hand, I refute the widespread belief that gains in security. This is wrong. Only an EPIRB officially registered can trigger appropriate and effective rescue in case of disaster. Not internet, or an Iridium phone will do. Except perhaps to alert in case of aggression on a specific area an association like STW which will relay the information.
In a previous post I mentioned the report Need / Price for choosing a computer system. Here I think we should establish, before embarking, report Advantages / Constraints : what benefits I expect to retire in connection with the sum of worries that it will cause me. This report is all the more crucial to solve for those who consider themselves as "zero IT".