Hi Larry,

Ok, so then you're saying that the data delivered by fluxgate compasses
was the problem. I can understand that, particularly as a small boat
always has far more pitch and roll than a larger craft. (My boat is small
as well) In fact, I recall something said by the owner of the boat I was
aboard saying something like autopilot wasn't that useful in rough
weather,
but that might well have been because you tend to need to head into it and
it shifts, while an autopilot might want to take you in a different
direction.

I would not say that the small tender is doing more pitch and roll than my
bigship.
The reason for the worse funktions are the hard knoking when it falls back
to the water
its nearly flying most of the time 40HP at 300Kilo gramms.

I am pretty sure that modern autopilots can and do accept NMEA data. That
must be the case as some advertise that they work with GPS to follow a
plotted course, so it would appear as if there wouldn't need to be any
modification.

The first promlem could be that the GPS data is comming out once a second
wile the compass
Data are 5 to 20 times a second appears.
All autopilots i have seen are using the compass for the direction and do
the correction with the
cross track information only.

I have the skills necessary to modify software (I'm a software engineer by
trade) but I doubt companies would release the source.

For my old DANAHELM it was the reason to remove it from the ship and replace
it with an
robertson AP3000 Danahelm is gone out of the business and i had not the time
to repair the
compass for a while. Later i saw that only one TTL in the output has blown.
The Danahelm uses an 80535 as the main prozessor so it could not be too
difficult to disassemble the
operating software. the robertson uses also an 8051 derivat.

Michael