AIS Transponder use

[PaulGooch]

I really meant for AIS class B transponders - many ships do not (yet) use AIS in the way us leisure users do - mostly they have perfectly adequate radar and visual means for lookout - therefore Class B transponder should not be relied upon to make you visible to shipping.

Ah right, with you now.

<snip>

Colregs rule5 will not be broken - as it has the term 'appropriate' in it - which is open to subjective discussion. I believe if 2 class B boats did collide - the fact that one (or both) were not monitoring AIS class B would be a less significant issue to visual lookout - assuming reasonable vis!

I just wonder if the wording of rule 5 makes the manufacturers wary of programming filters in, that might leave them open to legal action, especially in places like the US.

My thoughts on a selective filtering on Class B would be as such:
Display - user selectable icon to differentiate from Class A and a range & time to range filter so only class vessels B within X minutes of becoming closer than X Nm (could be fraction of) would be displayed.

Alarm - separate alarm triggers for Class A & B having independent settings as stated on those above.

If I had that facility then my display for Class B would be set to 10 minutes @ 1Nm - so any vessel that will be "within 1Nm of me in the next 10 minutes" would be displayed.
For Alarm on Class B - it would be off most of the time - but I would probably want an alarm on 10 minutes on 0.02Nm (<40m) max.

Seems to make sense. An option to completely turn class B reception off would also be useful. In the future, when more and more boats have transponders, busy areas class B icons could easily cause so much clutter that the plotter would be unreadable. We could otherwise end up switching AIS off completely in those areas.

For AIS alarms in general - Standard Horizon have a 'problem' ... if a vessels forecasted track comes within the guard zone it triggers the alarm - which is fine - except you have to acknowledge it - then, if the track goes outside the guard zone (by any amount) the alarm is reset - and once it comes back in again then the alarm sounds once more. - There needs to be a buffer zone so you're not constantly 'alarmed' by vessels that will pass on the fringe of the guard zone. Actually - thinking slightly deeper than that - vessels on the fringe could trigger a double beep that doesn't need acknowledging - whilst those that would enter an inner guard zone get the full warning ...
Damm - I wish I was a programmer!

Yes, my last plotter was Standard Horizon. Great plotters in stand alone mode, but poorly implemented AIS, Radar and compass integration. Even with a fluxgate compass, there is no "Heading up" orientation on the plotter. So, when at anchor or drifting, the plotter doesn't know which way your facing, it assumes you're facing the way you are swinging at anchor, or the way you are drifting. I changed to Raymarine, which implement AIS better and have a "heading up" mode.

 

[fireball]

I don't use Head up mode on the plotter - I like my charts to be North Up ... same as on the chart table!

 

[PaulGooch]

I don't use Head up mode on the plotter - I like my charts to be North Up ... same as on the chart table!

I knew someone would say that

I prefer mine to look like the sat nav in the car.

That said, my Standard Horizon still didn't display properly at anchor in North up mode, it ignored the fluxgate and consequently didn't know which way North was, until we moved.

 

[fireball]

Er - Sat Nav in the car is north up too ... that way I know which way I'm pointing and can tell if it's about to take me down a route that deviates from the direction I wish to travel ...

 

[PaulGooch]

Er - Sat Nav in the car is north up too ... that way I know which way I'm pointing and can tell if it's about to take me down a route that deviates from the direction I wish to travel ...

Ah, right, erm..... no answer to that then

 

[fireball]

Ah - don't worry - if there is facility provided - it should work correctly ...

I have 3 problems with the SH software:

1) Sometimes AIS data from the NASA AIS Engine (mk1) crashed the plotter - it would reset. My view is that NO incoming data should cause the plotter to crash - duff information should be disregarded. I don't have a NASA engine now though.

2) Port data view doesn't work at the moment - so I cannot 'see' the raw AIS data being fed into the unit unless I go into diagnostic mode - didnot help for troubleshooting the cabling!

3) AIS Alarms do not work in the way I expect - it seems to ignore TCPA setting meaning we get a CPA alarm even if the target is 15Nm and 2 hours away (it's stationary and we're doing 7.5knots!)

 

[PaulGooch]

Ah - don't worry - if there is facility provided - it should work correctly ...

I have 3 problems with the SH software:

1) Sometimes AIS data from the NASA AIS Engine (mk1) crashed the plotter - it would reset. My view is that NO incoming data should cause the plotter to crash - duff information should be disregarded. I don't have a NASA engine now though.

2) Port data view doesn't work at the moment - so I cannot 'see' the raw AIS data being fed into the unit unless I go into diagnostic mode - didnot help for troubleshooting the cabling!

3) AIS Alarms do not work in the way I expect - it seems to ignore TCPA setting meaning we get a CPA alarm even if the target is 15Nm and 2 hours away (it's stationary and we're doing 7.5knots!)

I also found various odd anomalies with the AIS alarms. Used to sit at anchor fishing in The Wash, with a large ship anchored a distance away, waiting for the tide. The AIS alarm used to keep going off, although we were both anchored. When we moved down the coast to Shotley, the first time i came into Harwich, all the ships in Harwich and Felixstowe sent the alarms berserk. I couldn't acknowledge them fast enough, so by the time i'd acknowledged half of them, they were all going off again. Had to turn it off.

Great little plotters and excellent value for money, but SH need to get the software sorted and updated as they are falling behind. Actually, they are made by C-Map and it's C-Map that do the software too.

My Raymarine works much more how i'd expect it too, using the same Comar engine as before. But, i still leave the alarms off as there is far to much heavy traffic here. I might switch them on if i went on a longish trip, if i remembered.