Jeff, I have used the Magellan SporTrakCOLOR for some time now. It has some fine maps but it also has a lot af fancy stuff that I appreciate. Worse, the display has low intensity and it just eats the batteries if you activate the backlight which happens every time you touch a button. So be carefull about colorscreens although they make reading easier. If you keep it on deck to read it's very fine and responsive. Jens Viggo, Denmark "I don't need a ton of fancy stuff that I will never use. I would like to be able to read it without my reading glasses. Of course, I want it as waterproof as possible. Does anybody have an opinion on which is the best brand and model? *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
I have used a Garmin Eterx Venture for a bit over two years now. Very basic unit and mine has proven quite waterproof. I cannot begin to count the number of times it has been submerged. Keep the battery compartment gasket clean and lubricated. The screen is small but you can enlarge the font in some of the screens. You will, of course, have to settle for less info displayed with the larger font. I use mine primarily for travel time and distance documentation and occasionally use the compass feature. Both fields are user programmable allowing the larger font. My biggest issue with the Venture is when I'm posting waypoints; the fonts are small when entering descriptions so I've become creative with my abbreviations. I'm a 50 year old who normally wears progressives but I don't wear my Rx glasses when paddling. The Venture is easy for me to read when set up correctly. I do, however, have to grab the readers when I'm studying a map. Pleasant waters. ~Holmes *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
~Holmes wrote: >I have used a Garmin Eterx Venture for a bit over two years now. > > >I use mine primarily for travel time and distance documentation and occasionally use the compass feature. > A GPS does document everything well but I still haven't bought one and really don't plan to. Am I becoming a dinosaur by holding on to my paper chart and deck compass and never planning on giving them up? A GPS is a very useful tool. I simply get a kick out of doing it all on paper and by eye. Especially the eye part. Makes me feel more connected to whats going on around me. Oh......and I am cheap too. If you gave me a GPS I would play with it although I would still prefer to do locations and crossings manually. I rarely paddle far enough to need to plot a course. Jim et al *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Jim Farrelly said: > A GPS does document everything well but I still haven't > bought one and really don't plan to. Am I becoming a > dinosaur by holding on to my paper chart and deck compass and > never planning on giving them up? A GPS is a very useful > tool. I simply get a kick out of doing it all on paper and > by eye. Especially the eye part. Jim, I try to do most of my navigation by map and compass, but when paddling around the shipping lanes or crossing them, the GPS provides important information. Since the lanes aren't marked on the water, and at least where I paddle, they are far enough off shore that it is impossible to take a bearing to a known site, the GPS is the only thing that lets me know where the lanes start and stop. Steve Holtzman *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Jim wrote: - >Am I becoming a dinosaur by holding on to my >paper chart and deck compass and never planning >on giving them up? A GPS is a very useful tool. G'Day Jim and Paddlewise, Here's an account I wrote up some months ago of a navigation training session during which we compared dead reckoning with GPS: - Was it 1.8km to the Red Point campsite turn off? or was it 2.7km? The directions had been carefully measured by GPS. Latitude and longitude were supplied. And yet that puzzling discrepancy! Anyway our coterie of navigation students passed the first test. It was a good trip - everyone arrived! So Saturday morning and we're all parked around two tables peering at maps and puzzling over protractors, while Stuart gives an introduction to navigation with a thought provoking description of dead reckoning and how it was used on long trips when you just had to get it right; plus a hair raising tale of what can go wrong when you rely too much on a GPS. It involved a naked blue man, standing on the beach, trying to attract the attention of an aged and perturbed couple. You had to be their to understand - but I'm sure if you ask nicely Stuart will repeat the story. And then we went to our kayaks and Stuart had us line all 14 of them up to magnetic north east. Well either Red Point shows alarming geomagnetic anomalies or we had learnt a lesson in how variable compasses can be. The lesson was to be careful with those cans of baked beans, those radios and metallic sail fittings and check the deck compass against a quality hand bearing compass. Finally we puzzled away on paper, trying to locate the Shangri La's of Jervis Bay, the elusive POINT A and the mystical POINT B. That well known navigational witch, Dee, applied her Portland Square dexterously and finished hours ahead of the rest of us, while we fussed with set-squares and protractors and struggled over the precise meaning of "east is least and west is best". And so it was we found ourselves paddling many kilometers along a variety of courses, which we have all sworn to keep secret. Then after much skillful navigation and accompanied by twenty dolphins playing in our wake, we arrived at a point within Jervis Bay of unmatched beauty and serenity, a point in which golden shafts of sunlight played and refracted and where Mariners, Mirages, Nadgees and Pittaraks were at peace together. A place, which we were told was TOTALLY the wrong place. Out by 900 meters if you checked by GPS. Was this the self same GPS which measured the turn off at 1.8km instead of 2.7km?? We analysed our results and the average dead reckoning error over a 10km paddle was 900m. There had been plenty of opportunity to select clear bearing points. But we were novice students in navigation. The most common error was to have calculated bearings in advance which were difficult to sight once on the water. It was the GPS, which was likely to have been correct. However, we did receive feedback that GPS could be quite badly in error when satellites were low on the horizon and cliffs affected the signal. I'ld be interested to know if anyone has experienced this? I personally learnt a great deal, much of which could not be found in books and most importantly the absolute necessity of practising theory in "on the water" exercises. And perhaps one day, when their is peace in the world, and yellow finned tuna jump from the sea into our frying pans, and Mirages, Pittaraks, Mariners and Nadgees paddle together in contented synchronicity, perhaps then we will find the elusive Point B! All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
> However, we did receive feedback that GPS could be quite badly in > error when satellites were low on the horizon and cliffs affected the > signal. I'ld be interested to know if anyone has experienced this? GPS normally displays its range of precision, which depends on the number of satellites that can provide a good signal at given conditions, i.e. geographical position, obstructions etc. I don't remember what is the lowest precision of my Garmin Legend (when it still gives some location), but must be better than 900m error of dead reckoning. I've heard of possible fog-induced distortion of signal, but haven't had a chance to check it personally, so don't know whether it is just "honest" weakening of signal (= honest lower displayed precision), or really distortion of data beyond stated range of precision (this would be much worse). *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 28 Aug 2004 at 13:39, alex wrote: > GPS normally displays its range of precision, which depends on the > number of satellites that can provide a good signal at given > conditions, i.e. geographical position, obstructions etc. You have to remember that the key word in EPE (estimated position error) is _estimated_. The GPS receiver has no way of knowing what the error is so it only estimates it. However, I frequently see my GPS showing an EPE of less that 15m. Note that 15m is the error that you can expect without SA. EPE is one thing on the GPS I choose to ignore unless it's significantly greater than 15m. Mike PS - Navigation is what you do with a sextant, timepiece and chart. Piloting is what you do with chart, compass and land references. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Mike wrote: - >Navigation is what you do with a sextant, timepiece and chart. >Piloting is what you do with chart, compass and land references. G'Day Mike and Paddlewise, Thanks for that it certainly got me thinking. But I have some questions on terminology applied to our "navigation exercise". We were using crude angular measurements (eg kamals and thumbs) to compare height and horizontal separation of land marks to estimate distance travelled, timepieces and an assumed speed to estimate distance travelled, compass bearings to landmarks to compare against precalculated chart measurements to estimate position and speed through the water. Was this pilotage, dead reckoning or coastal navigation, or all three? We used the GPS, i.e timepiece based distance and angular measurements to satellites to check our position against a chart. Would this be regarded as celestial navigation? Also I'm unclear about the differences between celestial navigation and navigation. Also to what extent is the word pilotage mainly used to describe guiding ships into harbour as opposed to coastal navigation which seems to be used to describe pilotage to find your way along the coast? All the best, Peter *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 29 Aug 2004 at 8:29, PeterO wrote: > We were using crude angular measurements (eg kamals and thumbs) to > compare height and horizontal separation of land marks to estimate > distance travelled, timepieces and an assumed speed to estimate > distance travelled, compass bearings to landmarks to compare against > precalculated chart measurements to estimate position and speed > through the water. Was this pilotage, dead reckoning or coastal > navigation, or all three? Dead reckoning and piloting. > We used the GPS, i.e timepiece based distance and angular measurements > to satellites to check our position against a chart. Would this be > regarded as celestial navigation? Actually, the GPS doesn't verify angular measurements, it determines distances to the satellites. The satellite transmits its position and time information. The receiver is able to use the time info to determine time of travel of the signal and hence the line-of-sight distance to the satellite. Conceptually, if you know the distance to four satellites and their exact locations, you can determine your own position. I think that atmospheric refraction and other effects are included in the calculations, but I'm not sure. The real calculations are done on earth-centered coordinates IIRC. BTW, if only three satellites are visible, then the receiver will _assume_ your current altitude (based on the most recent determination) and use that. Hence the greater uncertainty with only three satellites. GPS is essentially celestial navigation, however the constellation is not the stars, but 24 satellites (min) in six orbital planes. > Also I'm unclear about the differences between celestial navigation > and navigation. They are the same thing traditionally. > Also to what extent is the word pilotage mainly used > to describe guiding ships into harbour as opposed to coastal > navigation which seems to be used to describe pilotage to find your > way along the coast? Historically, they are the same thing. If a ship entered unknown coastal waters, they would use the services of a pilot. The pilots for Montreal harbour would board the ships downstream of Quebec City harbour in the old days. That's a couple of hundred kilometers outside the harbour proper. I had a relative that was an undercover RCMP officer and he would board Soviet vessels as part of the pilot crew back in the cold war days. It's interesting that the pilots were considered critical in those waters, since they were well surveyed. The first accurate survey of the St. Laurence River was done by a British officer named Cook. Seems he visited your part of the world, too, Peter! Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Mike wrote: - >The GPS receiver has no way of knowing what error >is so it only estimates it. However, I frequently >see my GPS showing an EPE of less that 15m. G'Day Mike and Paddlewise, Thanks also for the point you make about GPS estimation. I am pretty sure that the 900m error (i.e. a 10% error) on our "navigation exercise" was due to our inexperience with charts, compass and dead reckoning. Nevertheless we did hear a report of a GPS measurement that had caused a 1km error near Jervis Bay in the position of a yacht. This was ascribed to satellites being low on the horizon and cliffs interfering with the signal transmission path. If this kind of error really is possible do you have a feel for how the estimated error would be displayed on most GPS's? All the best, PeterO *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
I usually get an Estimated Position Error of about 12 feet with my old trusty old Garmin 12. And I've confirmed that accuracy many, many times visually over the years I've used it. Beware of the accuracy reduced intermittently when paddling under tree canopy as the distance logged may be understated. I find the GPS a valuable tool when navigating complex mangrove swamps and wetlands in Florida. They are particularly effective in combination with aerial photos or topos with lattitude and longitude lines. Thanks to everyone who shared information about their newer model GPS. I'm shopping, but still waiting for a model with Bluetooth. Al Vazquez KayakGuide.com - Places to Paddle - On Saturday, August 28, 2004, at 05:52 PM, Michael Daly wrote: > On 28 Aug 2004 at 13:39, alex wrote: > > However, I frequently see my > GPS showing an EPE of less that 15m. Note that 15m is the error that > you can expect without SA. EPE is one thing on the GPS I choose to > ignore unless it's significantly greater than 15m. > > Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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