Originally Posted by spudsdailey
I have a Simrad AC 42 and an AP48 head
unit. The chartplotter is a new Furuno TZT 14.
I am having trouble getting the two to communicate properly. As an example, when I Navigate to a "Go To" the auto pilot steers initially 25-40 degrees off target; then over a minute or two, it locks on to the proper bearing and is fine for the duration. Tried to re-calibrate; nothing works.
When I ask it to "Auto" course, it is fine; steers a perfectly straight course.
That is actually not surprising, and is "expected" behavior.
What the AP is doing is quickly bringing the boat
to be on top of the EXACT rhumb line between the starting point and destination
If your boat
is EXACTLY on a straight course toward the destination
, that initial deviation will be smaller, but still will happen--at least a little--as the AP figures out what heading is required to maintain the boat within 50 feet of the rhumb line course.
(Depending on your AP brain the "rhumb line" course might actually be a great circle, but the concept
is the same.)