A GPS routing how to

[T and C]

Tom -417

"We use a TomTom now but I am convinced it is a sin to use one while the DW is in the car. After all, the Bible says, "A man cannot serve two masters."

I hope that joke is not copyrighted! I am definitly going to use it.

Tom

[Wavery]

Originally Posted by Bill

I certainly stand corrected on one thing. I didn't realize that any consumer-oriented (as opposed to heavy commercial) GPS receivers were available in 1992 at a reasonable price. I was aware that cargo ships, for example, carried GPS, but they were quite expensive. It was Clinton's decision to turn off SA in 2000 that spurred the development of smaller, cheaper, more capable receivers.

The operator's manual for the GPS75 is pretty good. I notice that Garmin's decision to come out with lower-cost receivers included dumbing down the manual to the point where it is basically useless. When I got my GPSMap60 several years ago, I thought nothing could be more worthless than the manual that came with it. I was wrong. The manual that came with my wife's Garmin Colorado a few months ago has it beat by a wide margin.

I noticed one other thing. The manual for the GPS75 states that the accuracy is 15 meters, but there is an asterisk on that number. The asterisk states that the 15 meter accuracy is subject to a "degradation to 100 meters under Selective Availability". Since SA was always on, this was a bit disingenuous. Sounds just like vehicle tow ratings that we discuss on this board!

As for a sudden 50-miles position error? Whatever that was, it wasn't SA.

Bill

I (and other sailors) actually found our old GPS to be quite accurate.

For thousands of years it was a sailors vow to "never (under any circumstances) enter a strange harbor at night".

After the advent of GPS, it was quite common for sailors to guide a vessel into port by quoting the GPS waypoints that they noted from their own port entrance earlier in the day to a sailor that was trying to enter late at night, to avoid fowl weather or something.

The problem (as I stated before) was that the marine charts were so far off from the GPS coordinates that plotting the GPS coordinates on the chart would often show the sailor a course that would run him aground. It took a lot of faith to use the coordinates that some other sailor was quoting you over the radio aqnd ignore your own chart to enter a port in the blind (darkness or worse, fog).

In my many years of being helped and helping others with this sort of thing, I never heard of anyone having a problem. That tells me that the accuracy of the GPS had to actually be within a few feet early on. I once navigated a wide channel in Whangerai, NZ in just this manner. The bay entrance was about 2 miles wide but it was only about 3' deep in most parts (low tide). There was an old channel that was dug by the military during WWII. It was extremely windy and impossible to navigate the channel at night (even with lighted markers).

Our friends made landfall (sailing from Tonga) at ~noon that day. He made a waypoint for every bend in the channel and gave me the coordinates. I trusted this guy because he had been sailing longer than I had. We arrived at midnight with a historical storm (70-100kts of wind) bearing down on us. I used his GPS coordinates and had no problems. The bottom was mud and I motored up the 10 mile channel slowely so it wouldn't have been a big deal if I did run aground but I didn't.

This took place on June 5th, 1994.......
http://www.malenyweather.com/2010/06...irthday-storm/

I'll never forget that week as long as I live. That passage from Tonga to Fiji was the worst I ever experienced......Including Cyclone Bola in the Tasman Sea in 1988.

[T and C]

HarveyRV,

1. A man with 13 grandkids, (congratulations on the new one), has to have had some kids at home for many years. Did you take them to sea with you?

2. I am a retired teacher. Many history books state that early sailors stayed near land for safety reasons. I am of the opinion that the land is what a sailor wants to get away from for safety reasons. What do you think?

Tom

[Wavery]

Originally Posted by T and C

HarveyRV,

1. A man with 13 grandkids, (congratulations on the new one), has to have had some kids at home for many years. Did you take them to sea with you?

2. I am a retired teacher. Many history books state that early sailors stayed near land for safety reasons. I am of the opinion that the land is what a sailor wants to get away from for safety reasons. What do you think?

Tom

Exactly........most shipwrecks happen when vessels try to enter a port or seek refuge in fowl weather.

This is what happens when a ship tries to find refuge in a storm.


In most cases, we sat on a parachute sea anchor (far out at sea) during fowl weather. However, that particular storm was a killer and I was already too close to landfall.

The family thing is complicated. The kids did come sailing from time to time. The newest grandchild is 6 days old and a real sweetie. The smallest of them all (6# 13oz) and never makes a whimper.

[scrubjaysnest]

This is just to up date this thread since I wrote it originally with the Nuvi 550 in mind.

For the most part using Mapsource to load a route into the newer Nuvi's, 2XXX and above will get you in trouble. I have a work around for this.

1. Press the speed window and release it when you get to the odometer screen.
2. Press and hold the speedometer until you get the developers screen.
3. Scroll down until you get to where you change the device from MTP, mass transfer protocol to mass storage. You want to change it so any file manger program can read the device.

Note: back up your GPS including all hidden files first.

How to back up your Nuvi

The link tells you how.

4. Turn on your Nuvi and delete all favorites, (waypoints) and Trips, (routes).
You did back up everything first right.
5. Open Base Camp,( I really don't like this program), delete all waypoints and routes that are there. Back up this file if you want it later.
6. Withing nothing in BC import the route(s) from Mapsource (you have to save the Mapsource file first).
7. Now connect your Nuvi and when BC finally gets done reading it you can then send the route(s) to your Nuvi.
8. Verify its all on the Nuvi and your done.

This may also apply to 1XXX models also.