Originally Posted by DotDun
Admittedly, I don't have experience with more than 3 vendors APs, but I haven't found an AP that supports other than the compound sentences.
I agree that a lesser knowledgable type can mess things up at the UI. I would like to think AP designers would put failsafes in place such that when that happens (XTE missing), the AP would act differently (like refuse to accept the 'track').
I just looked at my Robertson (now Simrad) AP-20 manual. It just references
XTE and BWW. I think that these two single
items are all it uses, although you can send it the various compound sentences too. I expect that it just picks out these two bits of data. It does balk and announces NO VALID GPS
DATA if it is not receiving this information. I believe that it will use BWW, the bearing from a current
waypoint to a next waypoint, to intially point the boat in the desired direction. Then it appears to use XTE exclusively to make adjustments to stay on the course line. That is all it takes to correct for wind
. The chart plotter will use additional bits to display heading, but the AP does not need it.