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Old 24-09-2013, 19:03   #91
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Re: Big Ship Little Boat, who Gives way

Thanks to those who have brought me up to speed on the transponder function in AIS.

I am a bit surprised that sophisticated ECDIS systems cannot display position reports from DSC radios. This is a basic function on almost all modern chartplotters available on small boats. I have friends with both Raymarine and two types of Garmin chart plotters who have recieved position reports from my boat and report that they appear on their chart plotter displays. It would seem to be the same functionality that displays DSC based distress calls on the plotter. Are you guys telling me that large ship ECDIS systems do not display the position of a DSC distress call on the display?
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Old 24-09-2013, 19:31   #92
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Anytime someone complains that all CF threads deteriorate into chaos we should send them to read this. What a great thing to wake up to this morning. Thanks to the OP and to all the posters, everyone one of you have helped me learn something.
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Old 24-09-2013, 19:31   #93
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Re: Big Ship Little Boat, who Gives way

Quote:
Originally Posted by Dockhead View Post
Before I had AIS, my rule was I would not pass closer than 2 miles ahead of a fast-moving ship, nor closer than 1 mile to either side.
That's interesting. Very interesting.

In Puget Sound, the distance between aground on Skiff Point and aground on West Point is 2.45 nautical miles, and that distance includes north and south bound VTS lanes and a 1000 yard separation.

Things are, therefore, quite a bit more crowded here in the Sound than even I thought.

Freighters go tearing up and down the VTS lanes, tugs seem to ignore the VTS lanes, although after these discussions, I'm starting to think they ignore them because of us, and cruise ships come howling out of Elliot Bay going faster than anything except the Victoria Clipper, which will cost you a pair of panties.

Watching this thread, I got out my charts to see just how much room you guys were talking about, and you guys are talking about making decisions from outside my usual sailing grounds. If you take my last cruise, and lay off six or seven nautical miles from it, you're beyond Puget Sound. You're around some corner up in the arctic near Port Townsend.
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Old 24-09-2013, 21:33   #94
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Re: Big Ship Little Boat, who Gives way

Nigel, you have brilliantly summarized what many of us have been trying to explain for some time. We can only hope that the information you have given, is hoisted in by those who need it.

PS Your ship is similar to one I 'drove' for awhile.
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Old 24-09-2013, 23:29   #95
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Originally Posted by Jammer Six View Post

That's interesting. Very interesting.

In Puget Sound, the distance between aground on Skiff Point and aground on West Point is 2.45 nautical miles, and that distance includes north and south bound VTS lanes and a 1000 yard separation.

Things are, therefore, quite a bit more crowded here in the Sound than even I thought.

Freighters go tearing up and down the VTS lanes, tugs seem to ignore the VTS lanes, although after these discussions, I'm starting to think they ignore them because of us, and cruise ships come howling out of Elliot Bay going faster than anything except the Victoria Clipper, which will cost you a pair of panties.

Watching this thread, I got out my charts to see just how much room you guys were talking about, and you guys are talking about making decisions from outside my usual sailing grounds. If you take my last cruise, and lay off six or seven nautical miles from it, you're beyond Puget Sound. You're around some corner up in the arctic near Port Townsend.
I'm talking about open water - actually specifically crossing the shipping lanes in the Channel, which is 60 to 120 miles wide in the parts I frequent. Those were my personal, pre-AIS rules which were based on how much room I needed to safely avoid a last minute misunderstanding with commercial shipping.

None of this applies in ports or bays or anywhere with a channel, and anyway as Nigel and others have said, it's not really possible to formulate rigid distances and clearances which work for all situations, different crossing angles, relative speeds, etc.

However, I think it is possible to state a couple of somewhat valid rules of thumb - in open water you certainly want to fully understand the crossing no less than 4 or 5 miles out and at least have a plan, if not having actually maneuvered, and you surely had better not get within a mile without all maneuvers complete and definitely safe courses.

Again - that's open water. Reality will be different in crowded conditions, lower speeds, etc.
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Old 25-09-2013, 01:16   #96
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Re: Big Ship Little Boat, who Gives way

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Originally Posted by skipmac View Post
Just so you can see what's out there here's a couple of screen prints of the English Channel from marinetraffic.com

The vertical black line in the left picture I added for scale, is about 5 nm.
For those that have never tried sailing through something like this - yes it is more than nerve-racking the first few times. When there is enough traffic, and it is night, the helmsman can easily get confused when there are crossing ferries and ships in the lanes. WE don't have radar (or AIS) so we go at it with an HBC. It also means we never sail through the heavily traffic areas solo. WE are always two on watch. Needless to say, this means both of us are exhausted, giving rise to the further possibility of making mistakes.

We plan on installing both Radar and AIS (both receive and transmit), next year.

But cheer up Skipmac - I'm sure if you ask, someone on this side of the pond will be happy to take you on a night run down the channel ( or the Danish/Swedish sound). Gives you something to talk about at the club.
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Old 25-09-2013, 03:10   #97
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Re: Big Ship Little Boat, who Gives way

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Originally Posted by Dockhead View Post
I have the Sitex and am very pleased with it. It has built in GPS which works below decks, it has a USB interface with good setup and control software (even built in SWR meter!), and it talks to my plotters over NMEA 2000 (many don't).

I think there are several others of similar functionality and price which are equally good.
How does the internal GPS work out, is it possible to monitor the GPS satellite signal against an external mounted GPS antenna, and make a signal quality comparison?

Just asking as I'm looking at a transonder/transceiver with an internal GPS antenna, and if I can get away without having to run extra cables it would be a bonus
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Old 25-09-2013, 03:42   #98
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Originally Posted by nigel1

How does the internal GPS work out, is it possible to monitor the GPS satellite signal against an external mounted GPS antenna, and make a signal quality comparison?

Just asking as I'm looking at a transonder/transceiver with an internal GPS antenna, and if I can get away without having to run extra cables it would be a bonus
I think the specification requires a separate GPS receiver independent from ships main source of position data. So some of them have GPS receivers built in.

With Sitex, you have an excellent PC utility (probably the others have as well) which allows you to check signal strength, sats in view, position error, etc. I actually used the below-decks Sitex receiver as my primary position data source for a while before my network was fully sorted. Works great, and it is valuable that position data in the AIS is not subject to cable, connection, network problems.

Plus you have a backup source of position data (Sitex does not, however, broadcast this over N2K - only NMEA 0183). I feed my radios with position data from the Sitex for both DSC systems; very handy since neither speaks N2K.

In my installation, you can compare the Sitex position data with that of main system by reading position off the radio display. In my case, it's always in sync to at least two decimals, usually three.
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Old 25-09-2013, 03:58   #99
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Quote:
Originally Posted by carstenb

For those that have never tried sailing through something like this - yes it is more than nerve-racking the first few times. When there is enough traffic, and it is night, the helmsman can easily get confused when there are crossing ferries and ships in the lanes. WE don't have radar (or AIS) so we go at it with an HBC. It also means we never sail through the heavily traffic areas solo. WE are always two on watch. Needless to say, this means both of us are exhausted, giving rise to the further possibility of making mistakes.

We plan on installing both Radar and AIS (both receive and transmit), next year.

But cheer up Skipmac - I'm sure if you ask, someone on this side of the pond will be happy to take you on a night run down the channel ( or the Danish/Swedish sound). Gives you something to talk about at the club.
You get used to it. Believe me your HBC skills get polished up real fast! On a given average crossing, say Southampton-Cherbourg, which is 70 - 75 miles, you will have probably 8 to 10 encounters with ships which are close enough to require collision avoidance procedures (i.e. undetectable bearing change for part of the encounter). After a few dozen Channel crossings you've managed hundreds of ship encounters and you start to get into a groove.

One thing which makes it easier is the fact that we usually have a good sailing wind, and crossing N to S or S to N, usually some kind of reach, since the prevailing wind is W. Speed is life in these situations - 9 knots gives 150% of the ability to move out of any given dangerous spot, compared to 6 knots. I feel much better sailing hard at speed; you feel extremely vulnerable at low speed.

So Skipmac, yeah - come on over and Carsten or I will take you out and let you experience it for yourself. It's best at night!
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Old 25-09-2013, 04:31   #100
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Quote:
Originally Posted by Jammer Six

That's interesting. Very interesting.

In Puget Sound, the distance between aground on Skiff Point and aground on West Point is 2.45 nautical miles, and that distance includes north and south bound VTS lanes and a 1000 yard separation.

Things are, therefore, quite a bit more crowded here in the Sound than even I thought.

Freighters go tearing up and down the VTS lanes, tugs seem to ignore the VTS lanes, although after these discussions, I'm starting to think they ignore them because of us, and cruise ships come howling out of Elliot Bay going faster than anything except the Victoria Clipper, which will cost you a pair of panties.

Watching this thread, I got out my charts to see just how much room you guys were talking about, and you guys are talking about making decisions from outside my usual sailing grounds. If you take my last cruise, and lay off six or seven nautical miles from it, you're beyond Puget Sound. You're around some corner up in the arctic near Port Townsend.
That's like the Solent, not the English Channel. The Channel is a few hundred miles long by 60 - 120 miles wide with two TSS areas at the constricted parts of either end. Its about three times the size of Lake Erie. The Solent is a strait between the Isle of Wight and England which is mostly a couple of miles wide, but which carries all the traffic of Southampton, Portsmouth, and other ports on the Solent, p,us huge ferry traffic back and forth from the Isle of Wight.

In the Solent we have a restricted area at the entrance to Southampton Water where special nav rules apply - small vessels (including sailing vessels of any size!) must stay out of the way of larger ones no matter what, and must keep clear 1000 meters ahead and 100 meters to either side.

Despite dense ship traffic in this narrow strait, it is other sailboats which are the main hazard. There is a huge amount of racing here (Cowes and Hamble are both on the Solent) and on summer weekends there can be thousands - literally - of boats out. Racers infamously care little about the Colregs. Avoiding ships in the Solent is (unlike out in the Channel) relatively straightforward because their paths are rather predictable - you try to stay out of those areas if there is a ship anywhere in sight, and you are never more than a mile from a known safe area - a place too shallow for ships to go. And obviously, stay out of channels when there is any shipping in sight. So no need for much collision avoidance technique with ships here. It is the racers you have to watch out for - some of them will smash into you as soon as look at you . More than once, I've had a racer tack right under my bows, forcing me into a crash stop or other desperate maneuvers.
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Old 25-09-2013, 10:10   #101
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Re: Big Ship Little Boat, who Gives way

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[re. the term "Transponder"]
You are technically correct, but this is common usage and I believe the AIS specs also call it a transponder. I know the difference, but I'm still going to call it a transponder. ...
I forgot -- at least the Class-A, and possibly the Class-B transponders can reply in response to a query, which would technically qualify them to be called transponders.
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Old 25-09-2013, 14:07   #102
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Re: Big Ship Little Boat, who Gives way

Dockhead, that seems to say that in the restricted areas (Solent for you, the entire world for me) that simply staying out of the way does work.

I will point out, though, that here in Puget Sound, off Shilshole, the container ships, the tankers, the car carriers, all the huge monsters that wouldn't even know they hit me seem to stay in the TSS lanes. Or at least close to the TSS lanes. (I called them "VTS" lanes earlier, I have no idea where I got that)

But cruise ships, tugs, the ARGOSY boats, fishing boats and, of course, other sail boats seem to simply ignore the TSS lanes.

Now, after watching Raku earlier, then listening to you about collision avoidance, and thinking about last Monday, (I went sailing) I want to learn more about formal collision avoidance.

I track commercial craft from the moment I see them, using binoculars with a compass. I track the bearing, wait a couple minutes, then look again.

The only thing I know to do with this information is if the bearing doesn't change, we're on a collision course, and then I usually alter course until we're not even close to a collision course.

Now, "...from the moment I first see them" usually means when they come out from behind Point No Point to the north, and then they turn SSE by bouy SE at 47-55.4N x 122-29.5W and head down the sound.

From the south, most of the traffic comes out of Elliot Bay, and I first see them when I have a line of sight past West Point, at 47-39.7N x 122-26.2W.

If I'm wandering off into Port Madison, I see past West Point quite a bit earlier.

Overall, from bouy SE to West Point, according to my chart, measures 15.85 nm.

So my backyard is 2-1/2 nm wide at the choke point, by about 16 nm long.

I've never noticed a commercial vessel altering course for a sailboat, but this thread seems to be saying that it happens all the time. It also seems to be saying that he sees us first, but in our waters, I think I doubt that-- because of the turns in Puget Sound, I think we see each other at the same time, unless he has some way of seeing past land. When I'm headed to Port Madison, (a common destination for us) the first sight line clear of land is probably about 13-14 nm.

What I have seen, (every weekend, sometimes, like the opening day of yachting season, many times over the weekend) is a commercial vessel (sometimes a tug, sometimes a huge OMG freighter, occasionally a ferry) giving five blasts on his horn. Then we look around in panic and try to determine if it's us he's blasting.

The common "way" here is "stay the hell out of the TSS lanes."

I've seen and heard owners and sailors of long, long experience say and do just that.

A typical conversation goes:

"There's a tug to the north!"

"Are we out of the southbound lanes?"

"Yes!"

Everyone relaxes, and forgets about the tug.

Point one, that doesn't seem to be what you're saying.
Point two, it doesn't always work-- both ways. Commercial traffic leaves the TSS lanes, and if you take away the TSS lanes, none of us are ever going south of West Point. At least not under sail.

And the important point, point three, if I'm understanding you correctly, you're saying that what we're doing (stay the hell out of the TSS lanes) isn't enough, and can be as wrong as running a red light.

So am I understanding those points correctly?
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Old 25-09-2013, 14:30   #103
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Quote:
Originally Posted by Jammer Six
Dockhead, that seems to say that in the restricted areas (Solent for you, the entire world for me) that simply staying out of the way does work.

I will point out, though, that here in Puget Sound, off Shilshole, the container ships, the tankers, the car carriers, all the huge monsters that wouldn't even know they hit me seem to stay in the TSS lanes. Or at least close to the TSS lanes. (I called them "VTS" lanes earlier, I have no idea where I got that)

But cruise ships, tugs, the ARGOSY boats, fishing boats and, of course, other sail boats seem to simply ignore the TSS lanes.

Now, after watching Raku earlier, then listening to you about collision avoidance, and thinking about last Monday, (I went sailing) I want to learn more about formal collision avoidance.

I track commercial craft from the moment I see them, using binoculars with a compass. I track the bearing, wait a couple minutes, then look again.

The only thing I know to do with this information is if the bearing doesn't change, we're on a collision course, and then I usually alter course until we're not even close to a collision course.

Now, "...from the moment I first see them" usually means when they come out from behind Point No Point to the north, and then they turn SSE by bouy SE at 47-55.4N x 122-29.5W and head down the sound.

From the south, most of the traffic comes out of Elliot Bay, and I first see them when I have a line of sight past West Point, at 47-39.7N x 122-26.2W.

If I'm wandering off into Port Madison, I see past West Point quite a bit earlier.

Overall, from bouy SE to West Point, according to my chart, measures 15.85 nm.

So my backyard is 2-1/2 nm wide at the choke point, by about 16 nm long.

I've never noticed a commercial vessel altering course for a sailboat, but this thread seems to be saying that it happens all the time. It also seems to be saying that he sees us first, but in our waters, I think I doubt that-- because of the turns in Puget Sound, I think we see each other at the same time, unless he has some way of seeing past land. When I'm headed to Port Madison, (a common destination for us) the first sight line clear of land is probably about 13-14 nm.

What I have seen, (every weekend, sometimes, like the opening day of yachting season, many times over the weekend) is a commercial vessel (sometimes a tug, sometimes a huge OMG freighter, occasionally a ferry) giving five blasts on his horn. Then we look around in panic and try to determine if it's us he's blasting.

The common "way" here is "stay the hell out of the TSS lanes."

I've seen and heard owners and sailors of long, long experience say and do just that.

Point one, that doesn't seem to be what you're saying.
Point two, it doesn't always work-- both ways. Commercial traffic leaves the TSS lanes, and if you take away the TSS lanes, none of us are ever going south of West Point. At least not under sail.

And the important point, point three, if I'm understanding you correctly, you're saying that what we're doing (stay the hell out of the TSS lanes) isn't enough, and can be as wrong as running a red light.

So am I understanding those points correctly?
Collision avoidance is very different in open water, compared to in ports with channels and narrow straits with lanes, which was said many times in the other thread. And as was also said there - if you can just stay out of the way by staying in shallow water or out of traditional lanes, this is top best practice. In narrow straits, ships are not at speed and constant courses - they are anyway maneuvering - so techniques are different.

Your place is just like the Solent (2.5 x 16 miles) so I can relate. In doubt, we just bug out to shallow water, there. And absolutely, stay out of the TSS lanes - you are obliged to anyway, if the rules are like here!
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Old 25-09-2013, 15:04   #104
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Collision avoidance is very different in open water, compared to in ports with channels and narrow straits with lanes, which was said many times in the other thread. And as was also said there - if you can just stay out of the way by staying in shallow water or out of traditional lanes, this is top best practice. In narrow straits, ships are not at speed and constant courses - they are anyway maneuvering - so techniques are different.

Your place is just like the Solent (2.5 x 16 miles) so I can relate. In doubt, we just bug out to shallow water, there. And absolutely, stay out of the TSS lanes - you are obliged to anyway, if the rules are like here!
If you mean regular TSS lanes you are not required to stay out of then , merely that you must not impede vessels in them. Of course local rules may override things.

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Old 25-09-2013, 15:08   #105
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Re: Big Ship Little Boat, who Gives way

No matter what the rules and laws are.
Itís the law of TONNAGE. Get out of a big ships way as they always win the game of chicken.
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