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Go Back   SailNet Community > General Interest > General Discussion (sailing related) > Over reliance on electronics
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Topic Review (Newest First)
12-21-2012 06:17 PM
Brent Swain
Re: Over reliance on electronics

While crossing the Pacific, I have always kept an eye on other indicators of my whereabouts, like the height of Polaris and other constellations , birds , wave patterns etc.
Once, leaving Ensenada for Todos Santos , the fog rolled in and blacked everything out. I had cleared out, so I headed out. That was back in the days of satnav, before GPS. When I got there, a few of the Newport to Ensenada race boats were anchored there, and one invited me aboard. They asked if I had got any satellite fixes and I said "No." They asked how I found the place in the fog. I simply told them that,as it was late afternoon, all the birds were flying home. Those headed to my right were heading for the mainland, those heading to my left were heading for the point on the south end of the bay.Those flying up the middle couldn't be heading for anywhere else but Todos Santos, so I followed them in.
No problem.

Oh, you've done this before" was their reply.
12-21-2012 05:57 PM
travlineasy
Re: Over reliance on electronics

Quote:
Originally Posted by JonEisberg View Post
Would you consider doing that same passage, for the first time, at night?

That would be an example of what I would consider to be "over-reliance"...
After going through the first time, during full daylight, yes, I would make the same passage at night, but keep in mind I would follow my daytime trail that is recorded on the GPS/Plotter. I may be old and somewhat crazy, but after more than a half-century on the water I didn't suddenly become stupid. Now, it it was an emergency, at night, I would make the passage through the reef solely on my GPS/Plotter. Granted, it would be somewhat risky, but not nearly as risky of doing the same passage at night relying solely on paper charts. In that instance, the odds are squarely in favor of the electronics. Essentially, the same chart is on my GPS/Plotter, but with the GPS I know exactly where I am on that chart at all times.

Cheers,

Gary
12-21-2012 05:08 PM
JonEisberg
Re: Over reliance on electronics

Quote:
Originally Posted by travlineasy View Post
The depths on the GPS plotter, and the locations of the very shallow shoal areas were extremely accurate. When the chart-plotter revealed a 21-foot deep passage through the reef to the Atlantic's azure blue waters, the depth plotter's depth finder and bottom contour information was dead on. It also revealed a 4-foot deep patch of coral that was about 50-feet south of where I passed through the reef, and that's exactly where it was.

I guess my point here is that yes, this information is on the paper chart as well, however, the only visual reference point was Sombrero Light, which was about a mile away. The GPS/Plotter provided pinpoint accuracy, thus allowing safe passage through the reef. The passage area is about 150 feet wide, no one else was on the boat to sling a weight to test the depth, the waves were about 4-feet, thus the captain was glued to the helm in order to maintain course control. In this, and many other instances I've encountered in more than 6-decades on the water, that GPS/Plotter is far superior to paper charts. And, with the 20-MPH winds, that 3X4-foot chart would have blown overboard as soon as it was opened.
Would you consider doing that same passage, for the first time, at night?

That would be an example of what I would consider to be "over-reliance"...
12-21-2012 04:57 PM
noelex77
Re: Over reliance on electronics

It's rare to see anything other than WGS84 these days. Even with the right datum, however, the maps are still often wrong.
12-21-2012 04:17 PM
PCP
Re: Over reliance on electronics

Quote:
Originally Posted by travlineasy View Post
...
The depths on the GPS plotter, and the locations of the very shallow shoal areas were extremely accurate. When the chart-plotter revealed a 21-foot deep passage through the reef to the Atlantic's azure blue waters, the depth plotter's depth finder and bottom contour information was dead on. It also revealed a 4-foot deep patch of coral that was about 50-feet south of where I passed through the reef, and that's exactly where it was.

...
Most of the time is accurate but you have to know that sometimes isn't and if you have a over confidence on that accuracy you can get in real trouble. It had happened to me several times, not to be in trouble, but the accuracy being very poor, not to say misleading.

That has nothing to do with the GPS accuracy but with the charts that served as support for the information on the map in your plotter. The earth is not flat and the chart makers used different projection systems to make them flat. A good plotter has on the menu a choice of about 20 different projection systems used to make maps, to permit an adjustment between GPS position and the position marked on the map.

Many just don't know about this, other used cheap plotters that only have the most common reference system and even the ones that have god marine plotters will find that sometimes the system used for making the map is not available on the plotter. Those at least will know that in that region they will get inevitable errors, some with hundreds meters differences. And I am not talking just about exotic places, that happens for instance in Croatia that is one of the most common sailing destinations.

Believe me, many don't know about this. The guys on the Croatian charter company did not know nothing about it or that the plotter they had in the boats had the wrong setting or even that their plotter had a menu with different settings for different map systems.

Regards

Paulo
12-21-2012 11:59 AM
travlineasy
Re: Over reliance on electronics

A couple days ago, I decided to head offshore and try to find some dolphin just outside the reef, east of Sombrero Key Light. When conditions are right, the Sargasso weed stacks up in large patches this time of year, and when you find a good size patch of Sargasso weed you will usually find lots of Mahi-Mahi lurking beneath it.

The trip wasn't far from Boot Key Harbor, just 9 miles. The first leg involved passing through Sister's Creek, which is fairly deep until you get to the mouth of the creek, where the bottom quickly comes up to 5 feet. That means I have about a foot of clearance if I'm in the right slot through the channel, which is very narrow. That depth is displayed on my GPS/Plotter and an alarm goes off when I enter the 5-foot zone.

Once outside the creek in Hawk Channel I have two options - proceed down Hawk Channel, or head out through the reef. Heading down Hawk Channel would add a couple miles to the distance, so I opted to go through the reef. Now, I'm one of those individuals that loves to sail through the reef. I love watching the beautiful underwater world unfold beneath the boat, I enjoy seeing big grouper and barracuda fleeing as I approach, and the schools of reef dwellers can be fascinating.

The depths on the GPS plotter, and the locations of the very shallow shoal areas were extremely accurate. When the chart-plotter revealed a 21-foot deep passage through the reef to the Atlantic's azure blue waters, the depth plotter's depth finder and bottom contour information was dead on. It also revealed a 4-foot deep patch of coral that was about 50-feet south of where I passed through the reef, and that's exactly where it was.

I guess my point here is that yes, this information is on the paper chart as well, however, the only visual reference point was Sombrero Light, which was about a mile away. The GPS/Plotter provided pinpoint accuracy, thus allowing safe passage through the reef. The passage area is about 150 feet wide, no one else was on the boat to sling a weight to test the depth, the waves were about 4-feet, thus the captain was glued to the helm in order to maintain course control. In this, and many other instances I've encountered in more than 6-decades on the water, that GPS/Plotter is far superior to paper charts. And, with the 20-MPH winds, that 3X4-foot chart would have blown overboard as soon as it was opened.

I guess from my perspective, particularly as a single-handed sailor, the advancements in electronic navigation are essential tools - not just fancy gadgets or toys. Over the years I've found them extremely accurate and reliable. In my case, I've only had a single GPS failure, which occurred shortly after a near miss lightning strike in Chesapeake Bay, and a Loran-C problem, which was interference during a thunder storm. In both instances, I had no problem finding my way home.

Almost forgot - I didn't find the dolphin, probably because the wind had broken up the organized patches of Sargasso weeds.

Cheers,

Gary
12-21-2012 10:34 AM
JonEisberg
Re: Over reliance on electronics

Quote:
Originally Posted by MarkofSeaLife View Post
I never said i couldnt navigate. I have just finished an intricate overnighter from Ft Lauderdale to Key West, 175 nms , outside the reefs but out of the gulf stream so was within 500 yards (meters) of the reefs for much of the time, including sleeping, arriving refreshed enough to go out on my night of arrival.

It was a passage that no person could do without electronices but completely safe no matter what...
That would be news to any of those navigators aboard SORC raceboats in the St. Pete-Lauderdale Race from 1961 onward, just to name a few...
12-21-2012 10:14 AM
Flybyknight
Re: Over reliance on electronics

Quote:
Originally Posted by capta View Post
And I suppose you were able to get at least 2 LOP's for a fix in 2 hours and have as good a position as when the GPS came back on?

Yes.
12-21-2012 04:28 AM
noelex77
Re: Over reliance on electronics

Quote:
Originally Posted by Omatako View Post
Can't say I support that. Getting a fix on a GPS is easy, quick and generaly very reliable so to learn how to effectively do celestial nav in these times is, to me, a waste of time. If you have it and use it as a hobby and maaaaaybe in an emergency that's cool but starting now? No, I don't thinks so
Yes I do agree. I meant running fixes, DR etc. some people call this pilotage and some navigation.
I don't think cellestial is essential.




Quote:
Originally Posted by Omatako View Post
That level of redundancy is extremely rare on any boat - I'd be interested in what the 9 independent battery systems you have look like.
I am not sure it's rare these days, its hard to buy a phone without a GPS. For cruising sailors like myself our yacht is home so old computers etc accumulate. For the record between my wife and myself I have on board.
4 laptops.
2 iPads
2 phones with GPS.
2 handheld marine GPS units
2 fixed marine GPS units
2 older fixed marine GPS that still work.

My boat has 2 independent house banks plus an emergency battery mounted high up. So 3 house banks and a start bank which can be diverted to house bank. I also have a small 12v gel battery I use for testing and repairing equipment.

So that is actually 15 separate battery sources that could power a GPS and or maps. There are 10 GPS units on board.
I keep a couple of the units in a faraday cage.

So more than I thought now I have added it up. Some like the old laptop batteries are probably marginal, but the bottom line is there is lots of redundancy. This multiple level of redundancy is not necessary, but its what I have and it continues to increase as phone, computers and tablets are replaced with modern units.
12-21-2012 01:20 AM
wind_magic
Re: Over reliance on electronics

Quote:
Originally Posted by chef2sail View Post
While I aree with the first couple of paragaphs, the Bowditch example is not really a good one. Theier last major change was 1995. hardly modern
I have the 2002 Bicentennial Edition
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