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Jim Donohue wrote:
"Jeff Morris" wrote in message ... Jim Donohue wrote: Anyone who has been on a boat knows that a GPS *DOES NOT* for all practical purposes work all of the time. I've had a GPS fail several times, I've seen charting inaccuracies a number of times. Similar things have happened to almost every cruiser I know. You lead an unlucky life. I have never seen a significant outage of the GPS. I follow the tech literature on the subject. Aside from deliberate military actions the outages are very few, far between, and limited in time duration. As I said I have never seen one. You mean, other that the outages that have happened, there have been none? I'll admit the system has been pretty stable but individual satellites are taken down which causes minor hiccups. Several weeks ago, my wife's car GPS was off by a quarter mile for about 5 minutes - I have no idea what the cause was, but it could have been a problem on a boat. It is of course possible that you have a source of interference on your boat. That does happen. It is one of the reasons that multiple GPSs are sensible. Different devices have different weaknesses. I am sure there are also some specific locations that have a multi-path problem. Again though few and far between. GPS ain't perfect but it is very close. Done with redundant instruments on the open sea it is, for all practical purposes, perfect. The problem that has bit me a few times is that I use a handheld which is connected to its cable every time I use the boat. If the power connection isn't solid, it can fall back to battery power, and then shut off a few hours later. I keep spare cables and batteries, but when it happens, I'm down for a few minutes. And although I often have a chart cartridge, I've found occasional "dropouts" in the coverage - rather disconcerting when you're in a tricky section of the ICW and the chart screen suddenly goes blank. On my previous boat (Nonsuch 30) I would lose signal sometimes. I assumed it was from the wishbone boom, but others claimed the antennae was too low and the signal was blocked by crew members; perhaps both causes were factors. I've never been hit by lightning, by I know many others that have, and the GPS is frequently a victim. I've also heard of GPS's damaged by power spikes. Actually, the first time I took a GPS on a trip its menu button was damaged so it was virtually useless. Having a spare GPS, and batteries, cables, etc. on board is useful and prudent, but it doesn't help when you lose the primary in a tricky situation. While these problems are infrequent, and often "operator error" it does not mean they don't happen. And having a strategy to cope, such as carrying a redundant GPS doesn't help you for the time it takes find it and fire it up. The present cruiser population is certainly and effectively completely dependent on GPS for off shore navigation. At this point I don't think there are many exceptions left. I have not come across a report of a significant problem with that in a long time. What's your point? The vast majority of boaters don't go offshore. And obviously, piloting techniques are not commonly used off shore. You keep trying to equate piloting with celestial; they're are not the same thing. Charting inaccuracies are chart problems very close to completely. Without gps they are hard to detect. The ones on the West coast of Mexico however are detectible with a good LORAN. Without GPS the charting inaccuracies would not be as important. As I mentioned before, I watched a trawler run aground because they trusted the GPS and didn't watch the depth. None of these incidents were a major problem for me because I was using other techniques and was able to recognize the situation and compensate. The issue here is not which technique is the most accurate, or which should be used to the exclusion of the other. Continuing to cast it in these terms make you look like a jaxian fool. One uses all reasonable methods available. The first and primary of these is GPS. Your inablity to understand this simple statement is almost jaxian. The question isn't what should be used first; the question is what should be taught first. Your inability to understand that is beyond jaxian. Teaching someone GPS before basic piloting is like teaching children how to use a calculator before teaching them the addition table. The issue is that you claimed it was foolish to teach someone basic piloting, even when the person was eager to learn. This attitude marks you as a complete fool, Jim. I hope I never meet one of your students on the water. No my argument was that basic navigation...not piloting...was better taught with GPS as the primary technique. It was in response to an individual teaching basic navigation with electronic aids removed. Actually, the case was that someone was learning how to do LOP's and DR and wasn't interested in LORAN. You called this "utter nonsense." I call your attitude "sheer stupidity." It is even possible that the individual involved and I would end at the same end point. Just different routings. It is remotely possible, but someone who learns how to use a GPS first is rather unlikely to then learn basic piloting. And this is the essential point of my argument. Anyone can teach them self how to use a GPS; learning piloting usually takes instruction and practice. If I only have a student for a few hours, I'd rather spend time on something that's harder to learn, and just as important. Most of the concepts of piloting relate to GPS usage, so nothing is wasted. And you again utterly misstate my position. GPS is the first skill taught...it should be the centerpiece of the navigation system. Then others. Certainly even the dullest of students can learn to check a chart position via eyeball or radar. Are you daft, man? Are you claiming now that piloting need not be taught because "even the dullest" can do it without training? And radar too? Bizarre, considering you've confessed to have weak radar skills! Listen carefully. Pilotage is important. One teaches navigation with the GPS first. One person might do that, the rest of us will teach properly, thank you. The first portion of that instruction is the use of charts. agreed. A current student however should learn with the GPS positon centric techniques rather than the LOP techniques of conventional DR. DR doesn't involve LOPs. Its clear your understanding in this area is weak. Yes eventually these get taught also...but secondary to what is the real world. Eventually? Yea, right. You asserted that learning LOP's and DR was "utter nonsense." I think no one should be trusted with a GPS until the learn these basics. Uhhh where did it state that learning LOPs and DR was "utter nonsense"? I think I made such a comment about teaching a student navigation with such techniques emphasized to the exclusion of electronic navigation. Still do. Perhaps you should re-read your fist post in this thread. Dave said his daughter was enjoying learning LOP's and DR, and wasn't interested in the Loran. Your response was "Ohh stop...what utter nonsense." You went on to spew more silliness which only served to make you feel important and make everyone else think you're a fool. Nowhere was it mentioned that Dave's daughter would not go on to learn other techniques, or that she was even destined to be a boat's navigator. It was only stated that she enjoyed learning basic piloting. Frankly criticizing anyone for wanting to learn almost anything is a mark of a very small mind. You correctly point out that it will be difficult to teach DR/LOP after one learns electronic navigation. That is because it is difficult to convince the student that sufficient value exists in such techniques. You deal with this value problem by teaching DR/LOP first. There's a bit more to it, but OK ... I claim simple that this in no way prevents the knowledge of DR/LOP going away real fast. I think we need to develop that set of DR/LOP skills that will actually stick after electronic navigation is learned. If we can't develop such a set and convince the newby of value then the outcome is the same. The way to do this is to actively practice "manual techniques" even while using a GPS. I've never known someone who learned GPS first who did this. However, once you have actually navigated by LOP's, or following depth contours, or watching "danger bearings," it starts to become automatic. When I see a buoy line up with a point of land, I mentally follow the line on the chart and check the depth I should be in. It only takes a second, but would someone who had never done that "for real" bother to do it? I stress the electronic navigation first because I think it more important they do that well than that they master an initial set of techniques they will abandon upon learning the electronic version. First good at the primary system then good at the secondaries. Too bad the world doesn't work this way. We could teach calculators in the third grade because the kids could be trusted to learn long division later. I introduce VOR/DME and RDF merely to demonstrate that we really don't propose to teach all available navigation techniques...only those that we believe useful and reasonable. There are lots of techniques that are arcane or obsolete. They may be of interest to the advanced navigator or hobbies, but they are in a different category from piloting, especially when the equipment isn't often carried on board. The NTSB study blamed several "probable causes:" over reliance on GPS, and lack of training of the officers, and the failure to recognize the problem from other cues. This is a perfect example of problem with your approach. Claiming that your strategy works, but in this case they were incompetent is foolish. http://www.ntsb.gov/publictn/1997/MAR9701.pdf I am reasonably familiar with the report. Find for me any mention of over reliance on GPS. It does find fault with over reliance on the automatic features of integrated bridge systems. Calling it a "system" was a euphemism. It was a GPS attached to an autopilot. They ignored the depth sounder, the radar, and visual cues. Actually, the same thing could have happened to most anyone with an Autohelm and a Garmin, except the the Autohelm (now Raymarine) gives a better indication of faulty input. It also discusses flaws in the design of such systems. I agree that total reliance on a single GPS is not wise. I generally run three...and two are active in the process to try to avoid the entry errors that I believe are the worst problems with GPS navigation. When the europeans get their system operative or the Russians complete theirs I will almost certainly run one GPS off another system. I will also use other inputs like depthsounders and radar to help prevent errors. So you turn on 3 gps's for a day sail? I think you'd be better served by brushing up on more basic skills. |
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