Garmin chart plotter and AIS
- Thread starter jimi
- Start date
Twister_Ken
Active member
Missing info, Jim?
Twister_Ken
Active member
I've got the 555 combined with a Digital Yacht AIS receiver.
As far as I recall* it only shows the position of the AIS contact, not predicted course, but if you pull up the numbers, it gives the predicted CPA. Only played with in Lake Solent so far, not been used in anger.
*But I might be suffering brain failure, or maybe there's a bit more configuration to do in the menus.
As far as I recall* it only shows the position of the AIS contact, not predicted course, but if you pull up the numbers, it gives the predicted CPA. Only played with in Lake Solent so far, not been used in anger.
*But I might be suffering brain failure, or maybe there's a bit more configuration to do in the menus.
The Garmin 555 will give you "time to impact" plus yours and the targets course, but only if you have told it your destination which it needs to work out the two courses.
Learnt this the interesting way sailing from Gosport to Lymington. As we passed north of Cowes the AIS alarm went off warning of imminent death destruction and in less than 2 minutes. Looking around there wasn’t anything even close that could be considered life threatening. Then the GPS drew a red line from Calshot Spit area going south across our westerly track. Looking carefully we could finally make out the Red Funnel fast jet just making his turn off Calshot and lining up on us. With less than 90 seconds to certain death we altered course, the Garmin quickly computed the new course and that disaster had now been avoided so cancelled the alert. It was close but the Garmin saved the day, well almost, but you get the idea.
Pete
Learnt this the interesting way sailing from Gosport to Lymington. As we passed north of Cowes the AIS alarm went off warning of imminent death destruction and in less than 2 minutes. Looking around there wasn’t anything even close that could be considered life threatening. Then the GPS drew a red line from Calshot Spit area going south across our westerly track. Looking carefully we could finally make out the Red Funnel fast jet just making his turn off Calshot and lining up on us. With less than 90 seconds to certain death we altered course, the Garmin quickly computed the new course and that disaster had now been avoided so cancelled the alert. It was close but the Garmin saved the day, well almost, but you get the idea.
Pete
Hmm, I think it uses the data of speed and course from another vessels AIS to give a display of a possible collision. If one vessel alters course the plot on the chart plotter and the time to impact are removed or altered if the alteration isn't enough. So yes it must use COG and SOG for both vessels to arrive at this.
Pete
Twister_Ken
Active member
I don't have a transponder, just a receiver, so I don't know where an AIS transmission gets its input from for sure, but as it's broadcasting lat/long it must at least be getting some from the GPS. Whether the rest is coming from log (water speed) and compass (hdg) or also from the GPS (COG and SOG) I don't know. On biggies, something is also working out rate of turn - again whether that is ship's compass or change of COG I'm unsure.
Anyone know?
Anyone know?
The ship transmitting gives speed and COG, the GPS should give COG and SOG, it should then be able to calculate CPA and time based on these.
I've got a laptop program that does precisely that. However, I was hopingthat could dump the laptop anf use the chartplotter
I've got a laptop program that does precisely that. However, I was hopingthat could dump the laptop anf use the chartplotter
I have the small 180 Standard Horizon, connected to a comar AIS, and all the info is displayed on the screen. I can't see Garmin producing a chartplotter that can be connected to an AIS receiver, and does not.
Ah, just been back over this thread and I have missed a piece of information out.
Our Garmin 555s is connected to an Easy AIS receiver. I spoke to Garmin at the Southampton Boat Show a couple of years ago and since they didn't have an AIS at the time they recommended the Easy AIS, so bought one as well as the Garmin. All very straight forward to connect up.
Pete
Our Garmin 555s is connected to an Easy AIS receiver. I spoke to Garmin at the Southampton Boat Show a couple of years ago and since they didn't have an AIS at the time they recommended the Easy AIS, so bought one as well as the Garmin. All very straight forward to connect up.
Pete
Twister_Ken
Active member
Wee Jim,
Garmin will do all this...
http://static.garmincdn.com/pumac/GPSMAP421_OwnersManual.pdf
pp41 onwards
Garmin will do all this...
http://static.garmincdn.com/pumac/GPSMAP421_OwnersManual.pdf
pp41 onwards
yoda
Well-known member
Garmin and AIS
I have the 551 interfaced to a NASA AIS engine and i am fairly sure it just showes a target and when selected gives CPA etc. You can select the CPA range that activates the alarm and clasifies it as a 'dangerous' target (audible alarm and turns from green to red). I like it as I can just use the plotter in the cockpit without the laptop being on.
Yoda
I have the 551 interfaced to a NASA AIS engine and i am fairly sure it just showes a target and when selected gives CPA etc. You can select the CPA range that activates the alarm and clasifies it as a 'dangerous' target (audible alarm and turns from green to red). I like it as I can just use the plotter in the cockpit without the laptop being on.
Yoda