GARMIN GPSMAP 78 Heading question

[john_q]

I have recently purchased a GPSMAP 78, it is my first Garmin Unit and I have looked at the manual and tried posting this question on the Garmin site but so far no response from them

My query is that after our first 50 mile passage in rough weather withy the Garmin, we discovered that the HEADING setting was “too accurate”

This means that if the boat is rocking and rolling, the Heading keeps changing dramatically - up to 20- 30 degrees either side of the actual heading we were achieving.

Now this can be a real pain if you are trying to be really accurate crossing harbour bars or entering difficult reef entrances where you really need to be on the correct track

Our existing Furuno GPS 32 has a damping setting so that the heading you see is the average and you do not see the vast variations as the boat rocks about.

Is there any way to sort this out on Garmin units?

 

[Fantasie 19]

http://static.garmincdn.com/pumac//GPSMAP_78_OM_EN.pdf

Page 15 & 16???

 

[superheat6k]

I prefer not to steer in track mode because the plotter tends to want to hold too tight a line, leading to necessary zig zagging

Instead I steer in Auto and tune the heading with close attention to the bearing to waypoint. Once settled to a particular course, the B to W should remain constant, so if this increases then increase the heading, if it decreases decrease the heading. This means you, not the plotter, is driving the boat. It also means any specific deviation or other compass error affecting the auto helm doesn't matter.

By this method if you maintain a constant B to W then your COG must be straight. Bear in mind that any close channel such as described requires you to con the boat, and I would never rely on a dumb system to do this for me.

 

[john_q]

Thanks for the replies

http://static.garmincdn.com/pumac//GPSMAP_78_OM_EN.pdf

Page 15 & 16???

My GPS is the base model which does not have the electronic compass

I prefer not to steer in track mode because the plotter tends to want to hold too tight a line, leading to necessary zig zagging

Instead I steer in Auto and tune the heading with close attention to the bearing to waypoint. Once settled to a particular course, the B to W should remain constant, so if this increases then increase the heading, if it decreases decrease the heading. This means you, not the plotter, is driving the boat. It also means any specific deviation or other compass error affecting the auto helm doesn't matter.

By this method if you maintain a constant B to W then your COG must be straight. Bear in mind that any close channel such as described requires you to con the boat, and I would never rely on a dumb system to do this for me.

This is OK if you are doing a long passage, however when you are trying to enter through a reef entrance 30 feet wide with any seas running and you need to be on the money it becomes a bit scary

I have had a reply from Garmin UK at last

“Thank you for contacting Garmin Europe.

Unfortunately the heading dampening feature is only something included in our larger plotters. I apologise for the inconvenience this may have caused you.”

As we bought the GPS as the emergency spare for the grab bag this is not a major problem but it does seem to be something worth check before you buy the smaller units.

 

[europe172]

You should use a compass, your garmin is using boat position change to calculate heading, the slower you go the less good the results, I would always carry a compass just in case