[QUOTE=Kennebec Captain;113485]What I am saying is with my current ARPA is that it does not require own ship steady 3-4 minutes but computes new CPA/TCPA continuously based on heading/speed data it receives from the GPS. Other ship turns, yes, but not own ship, not with the gear I am using now at least. I wonder if that is what Cappy is dealing with?[/QUOTE]
Long Island Sound during the summer which is filled with people with too much money with too much boat and not enough experience dealing with tugs pinned or with it on a short wire. Either way, if I was there it would drive me STARK RAVING MAD! Better he vent here than run someone over that desperately needs it.
I donât know what heâs up to. True, the newer arpas track better, but they still teach 3-4 minutes, I suppose as a disclaimer or worst case. I think we are all saying the same thing here, be safe, be prudent, donât trust any one single source of info, and use your head at all times. Most any of us do this most all of the time.
In an attempt to use full and complete sentences⌠which make communication easier for all to understand:
The original question is about AIS on yachts, and how yachts are âseenâ on commercial vessels.
I know of NO RADAR set that is 100% capable of picking out a little sailboat out of the sea clutter under any circumstances. It appeared to me to be the OPâs question. Would AIS help him be âseenâ better.
My answer is thus: AIS puts a triangular blip, or some such marker on ECDIS, âeven NON ecdisâ and the commercial plotters available and in use on every vessel equipped with an AIS interface. I think it will be fairly soon that even âuninspectedâ towing vessels will all be mandatory to have such fitments. This âelectronicâ blip is FAR easier to see than an in discriminant, occasional radar target that may (or may NOT) be seen by the watchstander. Nevermind the capturing of the ARPA target.
An occasional RADAR target is often ignored as the seastate is adjusted for. AIS is either there, or it isnât. This makes the OTW observation so important. BUT, the OPs question was would AIS help (especially at night)
Regarding the ARPA function of being able to track through course changes, Maybe you attended a different course than I have. I was not taught your perception of ARPA ability (or more importantly liability)
If you cant see it on the radar then when you run it over it wont do much damage - Captains always told me that
So for yachts, get AIS and keep the F**k out of the way
PS Most commercial vessels on the high seas will not have the AIS on the radar that only became easy once flat screen radars turned up
[QUOTE=Kennebec Captain;113485]What I am saying is with my current ARPA is that it does not require own ship steady 3-4 minutes but computes new CPA/TCPA continuously based on heading/speed data it receives from the GPS. Other ship turns, yes, but not own ship, not with the gear I am using now at least. I wonder if that is what Cappy is dealing with?[/QUOTE]
I think the example should be with the lowest common denominator.
What is used on most all the commercial vessels. Yours may have some superior RADAR set. Mine doesnât have such adaptations. So to blanket state: âARPA tracks through course changesâ of âown shipâ is wrong. It only happens on vessels equipped like yours.
I keep AIS displayed on one radar and the other is turned off. The difference between the ARPA COG and AIS COG is sometimes +/- 5degrees!
I like to use the trails feature on my radar to help visualize when a vessel turns in a close quarters situation. That is, if I canât see his range/side lights. I always teach new guys to put an EBL from own ship on a target. If he is tracking down that line, well, you had better think about making passing arrangements
EBLâs on the radar and slap an azimuth circle on him too, yeah visuals! While ARPA is doing its thing, or not latching on at all, I like to use a long relative trail to get an idea then line up an offset EBL (or index line) down the middle of the trail, switch to true to monitor for any crazy Ivanâs (and decrease clutter). AIS info on a yawing sailing vessel doesnât tell me too much for sure, but at least I know heâs there.
did anyone mention that AIS gives speed over the ground and the Col regs are based on speed in the waterâŚ( Radar connected to log)
therefore at slow speed in current the AIS boat is giving false information regarding heading therefore you cant make a decision on right of way as you dont know the aspect
hence the IMO says its not a collision avoidance tool and rightly so ( as mentioned above)
[QUOTE=powerabout;113519]did anyone mention that AIS gives speed over the ground and the Col regs are based on speed in the waterâŚ( Radar connected to log)
therefore at slow speed in current the AIS boat is giving false information regarding heading therefore you cant make a decision on right of way as you dont know the aspect
hence the IMO says its not a collision avoidance tool and rightly so ( as mentioned above)[/QUOTE]
This seems to be unnecessarily complicated. The issue is making one self SEEN by whatever way possible. If the WAFIs canât even have Nav lights that are visible in heavy weather, I would at least like to âknowâ they are somewhere out there, via whatever method they can use to alert me. AIS does that. ARPA depends upon them BEing seen (and plotted) The issue of âcanât make collision avoidance determinationâ is secondary if I donât know the WAFI exists, it is even harder to determine if risk exists. Reading the earlier post about collision avoidance on yachts lets others know that yachters have a hell of a time even figuring out IF a risk exists, between them and a 900â merchant vessel! This guy is just asking for input on if there is âsomethingâ out there that would help him be âseenâ by us (prior to him getting run over)
[QUOTE=cappy208;113500]I think the example should be with the lowest common denominator.
What is used on most all the commercial vessels. Yours may have some superior RADAR set. Mine doesnât have such adaptations. So to blanket state: âARPA tracks through course changesâ of âown shipâ is wrong. It only happens on vessels equipped like yours.[/QUOTE]
Itâs not the radar or a plotting issue, it might be the algorithm used by the ARPA to calculate or an input averaging issue.
I"ll use an example. Say Iâve got two APPRs, a SUX-100, a WG-200 (works good) and a AIS. I am sailing due north and Iâve a vessel dead in the water dead ahead - 0 CPA. I execute a smart turn to starboard to a course of 030 and my actually new CPA is 1.2 miles.
Now I walk over an have a look at the WG-200, It is averaging and will take 3-4 minutes presumably but is averaging around the value of 1.2 miles. Maybe bouncing between 1.1 and 1.3 miles. Or maybe it is yaw, whatever. I donât care, I am looking for at least a mile.
But now I have a look at the SUX-100 and it is showing a CPA of 0.1. which given the magnitude of my turn and my seamanâs eye I know is wrong. It spends the 3-4 minutes averaging from the original 0.0 CPA to the new 1.2 mile CPA and is useless to me as far as verifying the new CPA as it may take a full minutes to show say, 0.7 mile CPA
The AIS is using GPS inputs and no plotting likewise would show 1.2 miles.
If you have a SUX-100 likely you would tend to check the CPA on the AIS more but with the WG-200 the AIS is used to aid detection and identification but not so much for avoidance.
Thats all good. but irrelevant to the original question.
How does a yachter make themselves more visible to not get killed. You may have the zuperdooper KC 200 radar. but if it donât see WAFI 30 heâs done for.
The only two useful comments on here seem to be: Buy the BIGGEST Baddest RADAR reflector you can find and hoist it as high as possible, and have an AIS.
[QUOTE=cappy208;113552]Thats all good. but irrelevant to the original question.
How does a yachter make themselves more visible to not get killed. You may have the zuperdooper KC 200 radar. but if it donât see WAFI 30 heâs done for.
The only two useful comments on here seem to be: Buy the BIGGEST Baddest RADAR reflector you can find and hoist it as high as possible, and have an AIS.[/QUOTE]
I am using a Furuno FAR2837, nothing out of the ordinary better then some worse then others. The trial maneuver is not user friendly and most mates find it not worth the time and effort. However when a course change is made it doesnât take 3 or 4 minutes to figure it out. Itâs probably not magic as it gets heading info from the gyro.
[QUOTE=cappy208;113552]Thats all good. but irrelevant to the original question.
How does a yachter make themselves more visible to not get killed. You may have the zuperdooper KC 200 radar. but if it donât see WAFI 30 heâs done for.
The only two useful comments on here seem to be: Buy the BIGGEST Baddest RADAR reflector you can find and hoist it as high as possible, and have an AIS.[/QUOTE]
And [B]ALWAYS[/B] assume that the big ship may have [B]NOT SEEN YOU [/B](for whatever good or bad reason)
[QUOTE=valvanuz;113557]And [B]ALWAYS[/B] assume that the big ship may have [B]NOT SEEN YOU [/B](for whatever good or bad reason)[/QUOTE]
Never assume ANYTHING! Do the best u can with what u have and then try and do better if it has to with SAFETY. You donât get too many chances to make mistakes out here that donât make a mark one way or another.
" The trial maneuver is not user friendly and most mates find it not worth the time and effort"
Man that is a understatement! Furunoâs trial maneuver is crap. For such a good radar why they couldnât provide a more user friendly means to operate trial Iâll never understand, Worth the effort? Yes, , but almost not worth it. As far as not taking 3-4 minutes probably not, but given time Iâd still let the arpa " think" on the solution for a while. No reason to make decisions on scanty radar info. Also, if you ever care to read the arpa IMO standards of performance, one would note that a mile CPA at times in various situations is barely acceptable if at all as the standard for acceptable error can be as large as +- a mile. Sure eats up your safety factor.
I am using a Furuno FAR2837, nothing out of the ordinary better then some worse then others. The trial maneuver is not user friendly and most mates find it not worth the time and effort. However when a course change is made it doesnât take 3 or 4 minutes to figure it out. Itâs probably not magic as it gets heading info from the gyro.[/QUOTE]
We have JRC (not a fan of anything JRC) and they still show the CPA change practically instantly. I like to compare AIS data with ARPA. If they are close I trust the AIS to be more accurate/precise, if I ever see a major disagreement I would trust the ARPA. ARPA is NOT a precision instrument as your vessel is yawing and rolling. I almost always see fixed platforms in shallow water showing 0.2-0.4 knots of speed (over ground).
AIS is not a precision instrument either, in fact neither are. If you are seeing a course and speed of a fixed object I could be that your radar is sea stabilized and the " true course and speed" are set drift. In fact this is taught in some arpa classes as a means to obtain approximate Set and drift in the area.
AIS is not a precision instrument either, in fact neither are. If you are seeing a course and speed of a fixed object I could be that your radar is sea stabilized and the " true course and speed" are set drift. In fact this is taught in some arpa classes as a means to obtain approximate Set and drift in the area.[/QUOTE]
No, they are almost always ground stabilized. When I switch to sea stabilization I see our set and drift, I have taught that to deckhands studying to be mates (it is an assessment they need to do), but on ground stabilization there is still a low speed and direction that fluctuates constantly.
