How Come

[SkiprJohn]

Aloha Talbot,

Thank you. I can see the utility of AIS as you have exampled. Since everything I do has something to do with economy I'm not certain that it should be required versus desired. Right now we're dealing with a state requirement for smallboats being required to have VHF or EPIRB if going one mile offshore. Seems like the government just can't stay out of our business. Cruising the islands here doesn't require much. There isn't much traffic and you are not out of sight of land for more than a few hours when transiting from one island to the next.
Maybe I'll have saved enough to afford more electronics but my first desires will be a small radar and a cheap GPS, laptop and electronic charts to get me to Alaska and down the waterway in 2008. I remember some severe fog when heading into the Straits of Juan de Fuca many years back. I do have a fair VHF.
In the mid '80s I did a Hawaii to Washington sail and for electronics had a good shortwave receiver and a VHF aboard. Shortwave was for weather reports and a "time tick." VHF was for close communication. The VHF was a nice to have item and I used it 4 times before making my first landfall. Radar would have been nice and would have prevented a near miss of a rock on the Washington coastline. Regards, --John--

[SkiprJohn]

Aloha All,

Oops. I forgot to mention that I had an old style EPIRB on the '84 cruise from Hawaii to Washington. Don't know if anyone would have found us using it but we did have it and I would have used it if we had definitely been sinking. Gave us some peace of mind. Regards, --John--

[Talbot]

I didnt make it clear that the AIS is a receiver only. John, in your situation I would agree that it is merely a nice to have. IMHO one of the best bits of kit I have purchased is a plotter that I can see from my helm, although that should stop you running into a rock, fog is a different matter, and not even AIS can protect you from all other vessels. For that you need radar. Admittedly, if you are not confident with what you are seeing, the AIS will help to resolve what is actually happening, and help you recognise contacts, but radar is the only means of seeing fishing boats and merchies that dont have a working AIS.

[dana-tenacity]

Would someone like to provide a glossary? What are all these acronyms?
It is possible to sail around the world with a compass sextant and leadline.

[Talbot]

you dont even need a sextant, you could make an astrolabe by using 3 pencils and 3 rubber bands. Good enough to run down a line of lattitude.

[Pura Vida]

"We the Navigators" By David Lewis. A great book on navigation, swells, stars, birds, and clouds as landmarks.

[GordMay]

A short biography, from the obituary for David Henry Lewis (1917-2002)
“The sailor who set out to see it all” ~ by Colin Putt
http://www.smh.com.au/articles/2002/...080913844.html

Traditional Navigation - See also:
http://www.janesoceania.com/oceania_...tors/index.htm
http://www.janeresture.com/navigators/index.htm

[Alan Wheeler]

We can get way to gadget dependant if we are not careful. I believe there is a clear necessity for balance. I know of extremes of cases. People sailing with no electronics at all and doing just fine and people that wouldn't travel 2ft without having a 3D pinpoint of exactly where in the water they are, and where in the world every possible hazard could be including seagulls. Ok so thats an exageration, but you get my point.
The biggest issue with these "data broadcast systems" if that is a good way to describe them, is the other vessel MUST have the thing and have it swtiched on, to make the "system" work. And so far, I don't believe the system is "working". Especially the vessel identification (can't remember the name) system on VHF radio. Not all the world has the system. SO for world cruisers, that is an issue as soon as they step ofshore. Not all the ships that have it are using it. The argument is that it gives compititors to much information on speed and ETA's of vessel. Don't ask me??I don't know why it's an issue. So most commercial vessels are not turning these systems on. So then comes the reliability and accuracey placed against the dependancy of the "system". Someone is going to depend on the "system" working and trust in it too much and be below and some ship is going to run them down because they never had their end of the system working.

[Sandero]

Wheelie,

The idea behind all these "gadgets" for navigation is not that you rely on any or all of them to be fail safe and accurate.

But the more data you get the more you add to the reliability of your DED recokoned position... or where you think you are and what is around you.

I don't rely on any single data source, but like to see what the consensus of the lot is. The more agreement there is, the better I feel.

Having said that, I do not interface my steering with position fixing devices like GPS. I insert my authority by "tranferring" and interpreting the data and then setting the heading to the autopilot. I also use the position fixers to verify that we are making the correct COG... radar images etc. As skipper, I read the data, process it and make the steering decisions as well as the sail trim.

I am a bit data dependent, but I still can read wind speed by oberving the waves, the flags, etc without looking at a gauge... and can read the clouds a bit as well regardless of what the weather forecast or even the barometer reads.

I don't see the point of ig noring technology. If Leonardo Da Vinci were here... or Galileo or Newton they would be using all the gear we all. I don't think they would be using an hour glass or sun dial to read time.

AIS is not a completely working system in that not all vessels are sending out data. But the ones that are make it a safety featuire for the yachtsmen who gains a bit more info and every bit helps.

[dana-tenacity]

I wasn't kidding, would someone like to explain this AIS thing?

[Vasco]

dana-tenacity,

Marvin Creamer sailed around the world without compass, sextant or electronic instruments in 1984. He didn't even have a wristwatch and he knew where he was most of the time.

[Pblais]

So throw away your watch and get out of here and go for it!

Just because Marvin does something really does not mean we all can or should do it too. It does not mean what he did is not significant nor does it mean that rest of us could / should do it too.

Wuld any of the great sea explorers have taken a GPS when they left for the great discoveries they made - you bet they wouldn't. They would have known there were no satelites in the sky to make it work.

[coot]

Originally Posted by jstevens

Pure Vida - There was a piece in Lat 38 about Mexico wanting all cruisers to have an AIS transceiver (or something equivalent), but that seem to be a still-birth. However I would not be surprised if our protectors at Homeland Security don't pick it up and start running with it.

Some people who do not understand the system have the mistaken belief that you can use AIS to enhance your security. The fundmental problem is that you trust the ship to tell you the truth about itself. If you assume that all ships want to cooperate to avoid collisions, AIS works fine. If you assume one or more entities has malevolent intentions, you can no longer trust the AIS data.

I'm not surprised that you see warships that don't transmit on AIS. Why would you give potential adversaries such valuable targeting data?

[Alan Wheeler]

Of course, Marvin had just poped out for a lazy afternoon sail and his wife was expecting him home for the evening meal. You could imagine the look on her face when he walked in the door a year later. "and just what time do you call this"

[Alan Wheeler]

Knottybuoyz, just for a little clarification on the AIS as you described above. I thought AIS was broadcast via Radar. Is this not the case. And how does that differ from DSC which is broadcast via VHF? Or is this the same thing???