MacGregorSailors.com

Quebec 1. That sounds perfect. Should take a few milliseconds and away you go. All the manual is saying is the order of computation. A nd, if for any rason the other sensors are missing, the compass gets the nod. Makes sense.
Dave

Keep in mind however that GPS heading is calculated and a few moments behind a fluxgate compass. If weather moves the boat unexpectedly GPS heading won't recognize the change for a few moments, and will have to compensate more. I would expect this to result in more squirrelly and less smooth course keeping. It would be interesting to hear your results.

Matt

Orion here.Thanks again for info.Pardon my two finger ops.,as I am just learning this com. lingo. Anyways I am glad not the only one using the bungy method for auto-pilot.Sure is alot of knowlege out there.we have decided on going with just chart-plotter for now.The garmin 531 is I guess a good choise for the Great Lakes with the blue something chip.feedback is welcome.Greg

Excellent Choice, Greg.

mastreb wrote:Keep in mind however that GPS heading is calculated and a few moments behind a fluxgate compass. If weather moves the boat unexpectedly GPS heading won't recognize the change for a few moments, and will have to compensate more. I would expect this to result in more squirrelly and less smooth course keeping. It would be interesting to hear your results.

Matt

Matt,
Excellent example of how a designer would use both information sources. As a designer, I would tend to favor the input of the compass until I was sure the vessel was making way. This could be cone by a simple proportional filter that gave more authority to the compass until GPS speed became significant.
Dave

In the navy, we have switch to an electronic nav system that is commercial off the shelf. it gets feeds from the Gps, gyro, compass Eco sounder and radar. its display shows heading AND course over ground. We use both readings to navigate.

chart plotters, if networked with everything, should do the same, as you need both to navigate safely, and if you have an auto, one is required to maintain the other if your following a planned track

Probably the main thing to keep in mind is the usage of the Mac.....no overnight passages to farflung ports....but day sailing in enclosed waters,rivers,bays etc as such the ability to let go off the wheel at times is great.On ours it has really made difference....I don't have to ask the wife to do things or hold the wheel. And as the Mac is relatively tender boat and its ability to round up causing direction changes we find our autopilot reacts to these changes keeping it on course really well.Our very cheap secondhand Raymarine sport pilot can be over ridden any time by just turning the wheel and it then continues on that new heading.Last year we sat basically in the same place on a river ,tide going out sailing against it on auto pilot for over an hour.......said the the cook "might as well put the kettle on we arn't going anywhere"