[PUP] AIS pitfalls

[Ron Rogers]

You can always check vessels in radar range. In decent weather, we've got 
binoculars. John used his eyes to correct the AIS data.

Ron Rogers

----- Original Message ----- 
From: "Dave Cooper" <swansong@gmn-usa.com>


| <John wrote: I'm used to seeing a projected course track that extends
| outward from  the target, the distance proportional to the ship's speed.>
|
| I believe that the projected arrow is from the course info and the ship's
| symbol is from the heading info. So if they are not in "approximate"
| agreement then you can have two conflicting pieces of information display.
| Then it becomes as matter of "which is correct?"
|
| If the ships gyro aka heading input to the AIS box is in error due to 
being
| wired incorrectly or some other issue then they won't even closely agree.
| The AIS GPS gives the course, the gyro or whatever is used gives the
| heading. A boat making with a heading of 90 degrees with show the ship
| oriented in this direction from the heading input however if it is 
drifting
| south then the projection line will be in this direction from the GPS.
|
| So the installation and the frequent check on the transmitted data is
| required. I would think that the system would be required to show on 
another
| display your transmitted information....easy cross check and would help to
| insure that you have inputted the correct data and that the black boxes
| feeding the AIS are doing so correctly. Without this what do you have??