RichardS
N/A
Do you actually use AIS?
As you are approaching a crowded anchorage you may well have dozens of collision/CPA warnings going off. If you don't turn off the AIS, or at least the alarms, you will lose your marbles.
Richard
AIS at the chartplotter
- Thread starter Sandy
- Start date
As you are approaching a crowded anchorage you may well have dozens of collision/CPA warnings going off. If you don't turn off the AIS, or at least the alarms, you will lose your marbles.
Richard
RichardS
N/A
Yep .... that's definitely anchored. If one needs AIS to avoid hitting it, it's time to go back to sailing school.Perhaps include this as a reminder.
Richard
capnsensible
Well-known member
One of the aspects I enjoy about teaching sailing is showing people how different techniques can be used to solve a problem in different circumstances. From transits, use of the hand bearing compass, radar, AIS, chart plotters, yadda yadda.
Recognising what is going to be the most useful in the circumstances one finds oneself. And being open minded when generally there is more than one safe answer.
Otherwise it would be as boring as driving a car.....?
Recognising what is going to be the most useful in the circumstances one finds oneself. And being open minded when generally there is more than one safe answer.
Otherwise it would be as boring as driving a car.....?
LadyInBed
Well-known member
That goes for approaching marinas as well! Definitely turn off alarms.
Re anchoring, once I'm anchored I turn off all my nav electronics and just rely on cone and light, should I rethink this?
GHA
Well-known member
Raspberry Pi stays on recording anchored position and a days worth of ais data, very unlikely indeed but if someone bashes into the boat at 3am (or any time) and are transmitting then they can run but can't hide.....
laika
Well-known member
What would be the minimum distance you'd want a ship to pass in front of you and how close to you do you think a ship would need to be before you could make a call as to whether its bearing was changing sufficiently to make you confident that it was going to pass that safe distance from you?
deeb
Member
I'm firmly in the yes I have AIS and use it (pretty much) all the time camp
A very useful feature when crossing a TSS is first check CPA, this lets you discard virtually all targets immediately - which significantly reduces watch keeping burden. Then: keep a track on their rate of turn - you will be able to see if they've made an alteration of course a long time before you would by Mk1. It can also be very useful to know their MMSI number. (You can make a bell ring on their bridge, which'll let you know if in fact there is anyone there, as an example)
Using mk1 and a hand bearing compass is a load of work in comparison and you don't learn anything of use until much later in the situation.
A very useful feature when crossing a TSS is first check CPA, this lets you discard virtually all targets immediately - which significantly reduces watch keeping burden. Then: keep a track on their rate of turn - you will be able to see if they've made an alteration of course a long time before you would by Mk1. It can also be very useful to know their MMSI number. (You can make a bell ring on their bridge, which'll let you know if in fact there is anyone there, as an example)
Using mk1 and a hand bearing compass is a load of work in comparison and you don't learn anything of use until much later in the situation.
DFL1010
Active member
If you're putting up a cone whilst anchored, then yes, maybe rethink
Although on a slightly more serious point, it can be useful to have AIS to see who's coming in. And of course gps and echosounder for dragging/tide.
RichardS
N/A
But what if your student already knows all the answers? ?
As for driving being boring, I reckon that your phailed phishing thread in the Lounge laid that one to rest.
Richard
GHA
Well-known member
Good example of just how useful ais can be. It will show small course changes many miles off ships make to give an an acceptable CPA, invisible to a hand bearing compass even in the most experienced hands. Means we can safely stay stand on and not behave like WAFIs annoying the professionals out there.
Stingo
Well-known member
Aren't you supposed to be welding and painting etc etc instead of posting sensible replies?Good example of just how useful ais can be. It will show small course changes many miles off ships make to give an an acceptable CPA, invisible to a hand bearing compass even in the most experienced hands. Means we can safely stay stand on and not behave like WAFIs annoying the professionals out there.
LadyInBed
Well-known member
Oh, what a Balls up!If you're putting up a cone whilst anchored, then yes, maybe rethink
I try and anchor in places that don't have lots of comings and goings and use a phone App for anchor watch.
Sandy
Well-known member
It's not a game of chicken.
It depends on a multitude of factors, wind, weather, sea state, location, state of the crew, state of the skipper, days out of port (
lustyd
Well-known member
It certainly feels like it in the TSS in the channel when you're the stand on vessel!
LittleSister
Well-known member
I have AIS (receive only), displayed on plotter, and find it really very useful.
As I often sail single-handed or short crewed it relieves a lot of the burden, and stress, especially when crossing the Channel, North Sea, Thames Estuary, or the like.
As has been pointed out above, it means you can immediately discount (at least for the moment) most of the ships visible to the eye at the time, and also see craft heading your way from over the horizon or otherwise not yet properly visible.
I see AIS as an adjunct to Mk.1 eyeball, rather than a replacement, but it does allow me to spend far less time crossing a shipping lane. I can pass more confidently through the traffic, and waste less time on slowing/stopping or altering course to give way to stand-on ships, or to give-way ships I'm not confident have taken the necessary avoiding action.
I find it very difficult to accurately gauge by eye the distance and speed of an approaching ship, and checking a hand-bearing from a small vessel such as I usually sail, much affected by waves and swell, is not accurate enough to be confident soon enough whether the CPA is a comfortable & safe one.
I've also occasionally had my attention drawn by the AIS to vessels I hadn't (yet?) even spotted by eye. E.g. a very fast moving 'target' (RIB?) heading my way from behind, that I wouldn't have seen by eye for some time as I plodded across the Thames Estuary at night, my main attention on a couple of ships coming downstream towards me on a converging course.
I'd like to have an AIS transceiver, but for the cost. The very modest cost of a receiver was money very well spent, in my view.
As I often sail single-handed or short crewed it relieves a lot of the burden, and stress, especially when crossing the Channel, North Sea, Thames Estuary, or the like.
As has been pointed out above, it means you can immediately discount (at least for the moment) most of the ships visible to the eye at the time, and also see craft heading your way from over the horizon or otherwise not yet properly visible.
I see AIS as an adjunct to Mk.1 eyeball, rather than a replacement, but it does allow me to spend far less time crossing a shipping lane. I can pass more confidently through the traffic, and waste less time on slowing/stopping or altering course to give way to stand-on ships, or to give-way ships I'm not confident have taken the necessary avoiding action.
I find it very difficult to accurately gauge by eye the distance and speed of an approaching ship, and checking a hand-bearing from a small vessel such as I usually sail, much affected by waves and swell, is not accurate enough to be confident soon enough whether the CPA is a comfortable & safe one.
I've also occasionally had my attention drawn by the AIS to vessels I hadn't (yet?) even spotted by eye. E.g. a very fast moving 'target' (RIB?) heading my way from behind, that I wouldn't have seen by eye for some time as I plodded across the Thames Estuary at night, my main attention on a couple of ships coming downstream towards me on a converging course.
I'd like to have an AIS transceiver, but for the cost. The very modest cost of a receiver was money very well spent, in my view.
johnalison
Well-known member
One of the uses for AIS that is seldom mentioned is when it can help you spot a ship coming out of a harbour long before it appears to the eye, as in places like Zeebrugge, or round a bend in the river, as in the Orwell, both something that the eyeball and even radar may be incapable of.
laika
Well-known member
The point of my question was to set the parameters for a trigonometry problem. You were saying it’s simple enough to check for constant bearing with a stanchion to determine risk of collision when crossing traffic. How simple making that “do I need to do something?” call is depends on how late you’re comfortable leaving it and what your safe passing distance is and I was going to illustrate that with an example of how much the bearing changes, or rather doesn’t, at the tcpa I’d like to know if I have problem. But if your parameters are different there’s not much point me wading through that trig
.Bottom line: I used to think most vessels were on a roughly constant bearing until they were much closer than I was comfortable with. Some maths made me realise how little the bearing of a vessel that’s going to cross comfortably ahead can be changing when it’s 20 minutes away. No way I could possibly judge by eye their 2 or even 5 degree course tweak to avoid me. AIS not only gives me better info far further ahead so that I can plan dealing with multiple crossing vessels much further in advance, practice at cross referencing what I can see with what AIS tells me has vastly improved my ability to visually judge ranges and chance of collision.
Don’t take my word for the “how much does the bearing change at what tcpa” thing...run some numbers (even if you have to spend some time working out how to do an inverse tangent with the Mac OS calculator
Because it *isn’t* a game of chicken I want better information sooner, which is why I like AIS to supplement my eyes and hand bearing compass.
Sandy
Well-known member
Following your selective snipping was my responseThe point of my question was to set the parameters for a trigonometry problem. You were saying it’s simple enough to check for constant bearing with a stanchion to determine risk of collision when crossing traffic. How simple making that “do I need to do something?” call is depends on how late you’re comfortable leaving it and what your safe passing distance is and I was going to illustrate that with an example of how much the bearing changes, or rather doesn’t, at the tcpa I’d like to know if I have problem. But if your parameters are different there’s not much point me wading through that trig
The posting started as a light hearted cheer about connecting two bits of kit that allows me to see something that I've not seen before, AIS data at the helm. I rarely look at the chartplotter. In my world it has two functions a) to collect data about where we have been for analysis after the trip and b) to keep crew entertained as I find these days most people only really understand what the computer tells them.
I spent my working life working things out to the nth degree, now I am retired I don't need to be so precise. If I feel that I'm going to get too close I lose a small amount of speed and the big ship will steam on by. I am not going to get to 95.67 meters from the other vessel and then ask the computer what I need to do.
I best not mention that the new radar is being delivered this week as my old raytheon radar has finally given up the ghost.
TiggerToo
Well-known member
Cone?
Eh?
Can someone remind me of where I should look this one up?
I thought I had to put up a couple of circles, crossed so that they look like a ball. Maybe I have been doing wrong all these years.
GHA
Well-known member
Now you have an AIS you just need to figure out what it does and how it can be useful, sounds like you've splashed out on a handy timer but are still randomly trying to figure out when the egg is boiled in your head .....
A glance now and again will tell you what will happen when the ship is stil miles away without you guessing or having a computer tell you what to do.
Or acting like a WAFI......