Like any addict, I really like to get my fix. I know that I can navigate coastal waters by bearings, soundings, dead reconing and my paper charts. I even know enough celestial navigation to make sense of all of the references and tools that I have onboard for when I go offshore. But I prefer to have a Global Positioning System fix.
The problem is that when I turn on my GPS devices, they sometimes take half an hour to obtain a fix, and rarely get a fix is less than five minutes. I understand that the average time for a fix is supposed to be less than a minute. But with my dedicated antenna 8 feet above the stern or my hand held in the cockpit I never see that kind if behaviour, even when I literally have not moved since the last fix.
GPS is really useful. We would never have gone into some of the coves where we anchored in the broken group without it. But it's failure state is terrible. GPS either tells me my position to less than a boat length, or it tells me nothing at all. If my GPS is getting a clear signal from four satelites it tells me nothing. If there happens to be a mountain in the way of the others or whatever else causes my problems, I get nothing. Not a position plus or minus 1 degree, nothing at all. And that tells me that I can't rely on it.