how accurate is your compass?

[DGR]

I use my GPS chartplotter 100% of the time...

Until it broke. Then I got out my chart, chinograph pencil, and used my compass (accurate to within 5 degrees, by the way) and got home that way.

The point is that technology is great, but you also need the skills (and the confidence that brings) to deal with having to 'go manual' when the brown stuff hits the fan. And believe me, it will, at the MOST inappropriate time.

D...

[Tomas]

Originally Posted by wavelength

As for not being able to get round without gps, before we had that it was Decca which was not reliable in various weather conditions and before that we used fast small boats at sea on long trips fishing etc with just the compass and a watch. I dont remember hitting anything then-although a lot of guys from our boat club did manage to end up a long way from their intended destination.
Gps is brill, and I would feel vulnerable without it now that we have all got so used to the accuracy it gives and we have chart plotters on the boats and hand helds a a back up-but life at sea did exist before gps!

Aye, there's a man with salt in his Beard!

You are absolutely correct in what you say however it's a shame you purchased a French Chart Plotter, Magellan (Just a guess from your report) Garmin is heads above the rest. When I went Hi Tech I had a Micrologic Loran that only displayed Time Differentials and had to either convert to obtain Lat/Long or have charts that displayed TD's. Not a unit for small open boats, that's for sure. I remember the first "Sat. Nav.(NAVSTAR)" I saw, it was a Motorola on a yacht and the guy said it set him back $35,000. Have we ever come a long way!

My advice to anyone going to sea, among other things is to go bust for a copy of "Dutton's Navigation and Piloting" and study all 587 pages front to back and back to front. Don't however take the book RIBING with you, take the damn GPS and a $10 compass.

All this GPS and Compass talk made me realize how much I miss my old friend Mr. Freiberger. I just had to get him out of his crate and express my continuing love! We share a few secret moments that as I recall include being scared Sh1tless.

[Tomas]

Duttons:

"It is known that there have been 12 reversals of magnetic polarity over the past nine million years and we are overdue for another. The Earth's field intensity has decreased 50% in the last 4,000 years and it is predicted that in 1,200 years or so magnetic compasses will become useless - there will be no field to direct them and they will point in any direction. When the field returns a few centuries later, its polarity is more likely than not to have reversed."

Tomas says, "Wul I think I'm going up South to do some snow skiing".

[bedajim]

Mine is crap due to all of the toys

So I've got a good hand held with light and a cheap hand held

a fixed gps and a hand held gps with separate mapping software + 2 sets spare batteries

We rarely go out of sight of land and I also carry heat sealed charts

[wavelength]

you purchased a French Chart Plotter, Magellan

bollox - have a look back in the forum for all the problems that folk have had with a certain make of marine electronics and their infamous after sales service and the ability of their kit to fail when its wet.
So no it wasnt a magellan, we have one of theirs and its fine - we do also have, and have had in the past, a number of garmin gps sets and have always been very happy with them.

[codprawn]

Originally Posted by Blackroady

Its not just your unit that can pack up - have been occasions when the whole thing has stopped at times . MOD have undertaken trials & blanked signals in the west counrty for hours at a time ................. hard to interupt the north / south pole . BUt yes handheld is well worth it for very little money compared to what they can do nowadays !

It is because of the vulnerability of GPS to jamming etc that it has been decided to continue with the old LORAN system. new transmitters are being installed - accuracy can be as good as 8m!!!

http://www.trinityhouse.co.uk/media_....html?id=15001

[Rogue Wave]

Originally Posted by Tomas

.

Reliability of GPS chart plotters is bulletproof.

Anybody that risks there life on the ability of electrical connections or electronics on an open rib is a fool.

Switch on a GPS and the first thing you see is a disclaimer telling you that the GPS is not capable or not warranted to replace conventional navigation methods. That's good enough for me!. GPS's are fantastic devices but they are electrical and electrics fail. You have to be able to resort to conventional methods.

I spend a lot of time on commercial Ships from dodgy old commercial tugs to the most sophisticated ROV/DSV's. I have never been on a ship that didn't have at least 3 stages of redundancy on the electrical supply, How many does the average RIB have.

Commercial ships are required by the IMO to manually plot there position on a chart every hour, how they gonna do that if the don't get trained in conventional Nav.

The Sea is similar to a Polar bear beutiful, large and awexome but it will kill you in an instant and it's never your friend.

As articulate and reasoned as your arguments are I think they are fundamentally flawed and I urge you to reconside. Don't forget the fundamental rule of safe boating plan for the worst and hope for the best

[Tomas]

No problem and I appreciate your comments amigo.

At no time however did I reject possession of a compass as being a good idea. I strongly suggested however that high speed rides in coastal waters simply require a GPS Chart Plotter for the first line of defense. If in the unlikely event the GPS packs it in, slow down first and go to plan B second.

I called my compass my good luck charm. That's because I believe in making my own good luck.

[Tomas]

Originally Posted by codprawn

It is because of the vulnerability of GPS to jamming etc that it has been decided to continue with the old LORAN system. new transmitters are being installed - accuracy can be as good as 8m!!!

http://www.trinityhouse.co.uk/media_....html?id=15001

Codders...I'm surprised to read that article but it says what it says. Are there small weatherproof Loran units available in Europe?

The doubts about GPS make me wonder how much of it is lack of faith in the old US. As far as I know Uncle Sam owns the entire satellite array and can do with it what they like. I was fishing full time a few years back before the Navy quit using Vieques as a bombing range and we had frequent naval exercises in the area. On several occasions when there was a lot of aircraft, surface and presumably submarine activity in our area the GPS signal would drop out completely for an hour or less. I never did know if the events were related but it gave me cause to wonder. Aircraft use GPS to transit between Vector Points and I don't even want to imagine the consequence of dropping satellite transmissions for crowded air routes.

I'm not aware of any enhancement to Loran, or frankly if it even remains operational in North America. I should have done a search first but it seems that if it were around that fact would have crossed my chart table! They did institute something called Differential GPS which offered a Loran like time delay enhancement to the coastal GPS receives, if that capability was present in the receiver. Since the military quit the Selective Aquisition business which degraded accuracy on purpose, I haven't even heard much about DGPS either?

Do they feel that terrorists would jam the GPS system, or an ill intentioned country?

I learn something new every day???

[Tomas]

So I did a quick search and Loran C remains operational for the lower 48 and Alaska. I also found a link to the Federal Register where the Department of Transportation called for "public comment" in January of 07 on the future of Loran C in the US.

1. Maintain the existing system
2. Shut the system down
3. Enhance the system

Don't have a clue as to what direction they're headed but I do not believe that any electronics manufacturers are in production on all weather small receivers for the consumer market, but I stand to be corrected if this is not so. I didn't even think the damn system was still up

[Tomas]

Ah ha.

I found this opinionated site that never the less describes what's going on with the Loran C issue. It appears from the comments that Loran C is kept on life support as a backup to commercial air traffic, only. No one wants to build combo GPS/Loran receivers due to the uncertainty of its future.

There are some nasty comments relative to European Politicians imbedded in the article....I just can't imagine

http://phk.freebsd.dk/loran-c/Politics/

[codprawn]

My main concern with all digital systems is the ease with which they can be jammed. For example you can get a mobile/cell phone jammer the size of a briefcase that will take out a whole street.


It is a similar situation with GPS - even if deliberate jamming is unlikely accidental jamming does occur.

"Man-made interference can also disrupt, or jam, GPS signals. In one well documented case, an entire harbour was unable to receive GPS signals due to unintentional jamming caused by a malfunctioning TV antenna preamplifier. Intentional jamming is also possible. Generally, stronger signals can interfere with GPS receivers when they are within radio range, or line of sight"

And read this about home made jammers.

http://computerworld.com/securitytop...,77702,00.html

[Limey Linda]

I think it is important to diferentiate between the two purposes of a compass.
They can be used as a steering compass or "location/bearing compass"
For the latter a hand held is just fine. If you are out of site of land on a cloudy day or at night or in fog then a hand held will tell you which way to go to get to land. I personally find any analog steering device easier to use to steer by than a digital one, However, you need to learn how to average your course. However, if you have not studied a chart of your boating area you are probably "up a creek without a paddle" anyway.

[Tomas]

[QUOTE=codprawn;216053] My main concern with all digital systems is the ease with which they can be jammed. For example you can get a mobile/cell phone jammer the size of a briefcase that will take out a whole street. Quote]

I don't know if you read the essay on the link I provided but that guy agreed that jamming GPS is dreadfully easy. He further stated that Loran "radio" signals were far more robust but the ease of which the transmitter sites could be targeted makes that system vulnerable.

This has probably gone out of the compass realm at this point. I'm going to do some more digging and post to the Electronics Forum.

[Tomas]

I hereby retract my statement that GPS is Bullet Proof. For those of you fortunate enough to be in areas of Loran C coverage though, help is on the way. The discussion is in Electronics under Loran C/GPS/? There are some very interesting comments there by an industry player. Integrated eLoran/GPS receivers are on the way for marine applications and will provide something much closer to bullet proof reliability. Cost is not announced but usually within a reasonable period of time costs come down....

Tomas

[wavelength]

[hobbit555]

I cannot believe that people will pay tens of thousands if not hundreds of thousands for a boat then begrudge a hundred or so for a professional compass swing by a compass adjuster.
Compass any day for me.