Alan Gomes
Sustaining Partner
I sail out of L.A. Harbor (San Pedro), which is a commercial port with a ton of large shipping. I do not have radar but figured I should at least get AIS receive capability, especially for when the weather gets soupy in the shipping lanes.
I just installed a Standard Horizon GX2200 VHF radio, which also contains a built-in GPS, DSC, and AIS receiver. It seems to be working fine based on my quick test yesterday at the dock. It functions as a stand-alone AIS receiver with its own display for targets, or it can be interfaced easily with a chart plotter.
I have a couple of questions for those of you familiar with AIS.
(1) I'm wondering about what settings you might suggest for the CPA and TCPA alarms, particularly in light of the high density of AIS targets in L.A. Harbor. My thought is to set the CPA to something like 1 mile (with the CPA alarm off) and then set the TCPA to maybe 15 or 20 minutes (with the TCPA alarm set to "on" once I'm outside of the harbor). My reasoning--which may be faulty because I'm just now learning about this--is that if I set the CPA number too large I'm going to get a ton of hits. By setting it at 1 mile, or perhaps even 0.5 mile, it should cut down on that. But then having high enough number of minutes before it sets off the TCPA alarm would give me adequate time to alter course, ring up the ship if that were necessary for some reason, etc. I would not even turn on the TCPA alarm, though, until I was outside of the harbor, maybe a few miles past the L.A. Light. Just sitting in my slip yesterday there were an abundance of targets within half a mile of my boat! Many of these vessels were at the dock with their transponders on (SOG = 0.0). I wish the GX2200 could filter out the ones that are stationary, but it does not appear that this is possible. Once I get outside of the breakwater a ways that should clear things up.
(2) My GPS is a Garmin 546S. It has a 5" screen. I can easily interface this unit with the GX2200 in order to show the AIS targets on the chart. However, I wonder whether this might actually be counterproductive. 5" is a small screen and it seems as though I'd have lots of little triangles clogging the display much of the time. More to the point, I'm not sure how valuable seeing the targets on the plotter would be vs. the display on the radio anyway. I'm thinking that the main thing is having the TCPA alarm alert me, which I can easily hear from the cockpit. If it goes off, a quick look at the GX2200 display will show me where the ship is relative to me. Any of the calling functions, should I choose to use them, would be done from the radio anyway. I may go ahead and wire it up to the Garmin just to see what I think, but if there is a strong consensus otherwise I might forego that.
Thanks for enlightening me on this new-to-me technology.
I just installed a Standard Horizon GX2200 VHF radio, which also contains a built-in GPS, DSC, and AIS receiver. It seems to be working fine based on my quick test yesterday at the dock. It functions as a stand-alone AIS receiver with its own display for targets, or it can be interfaced easily with a chart plotter.
I have a couple of questions for those of you familiar with AIS.
(1) I'm wondering about what settings you might suggest for the CPA and TCPA alarms, particularly in light of the high density of AIS targets in L.A. Harbor. My thought is to set the CPA to something like 1 mile (with the CPA alarm off) and then set the TCPA to maybe 15 or 20 minutes (with the TCPA alarm set to "on" once I'm outside of the harbor). My reasoning--which may be faulty because I'm just now learning about this--is that if I set the CPA number too large I'm going to get a ton of hits. By setting it at 1 mile, or perhaps even 0.5 mile, it should cut down on that. But then having high enough number of minutes before it sets off the TCPA alarm would give me adequate time to alter course, ring up the ship if that were necessary for some reason, etc. I would not even turn on the TCPA alarm, though, until I was outside of the harbor, maybe a few miles past the L.A. Light. Just sitting in my slip yesterday there were an abundance of targets within half a mile of my boat! Many of these vessels were at the dock with their transponders on (SOG = 0.0). I wish the GX2200 could filter out the ones that are stationary, but it does not appear that this is possible. Once I get outside of the breakwater a ways that should clear things up.
(2) My GPS is a Garmin 546S. It has a 5" screen. I can easily interface this unit with the GX2200 in order to show the AIS targets on the chart. However, I wonder whether this might actually be counterproductive. 5" is a small screen and it seems as though I'd have lots of little triangles clogging the display much of the time. More to the point, I'm not sure how valuable seeing the targets on the plotter would be vs. the display on the radio anyway. I'm thinking that the main thing is having the TCPA alarm alert me, which I can easily hear from the cockpit. If it goes off, a quick look at the GX2200 display will show me where the ship is relative to me. Any of the calling functions, should I choose to use them, would be done from the radio anyway. I may go ahead and wire it up to the Garmin just to see what I think, but if there is a strong consensus otherwise I might forego that.
Thanks for enlightening me on this new-to-me technology.