GPS>> Distance from Compass

[Spaniard_King]

just reading through my new GPSMAP manual and it states in the specifications section.. in small writing Compass safe distance 95cm

My last chartplotter was mounted only 20cm from the compass.

Does anyone know of problems that can occur from mounting the GPS too close to the compass??

95cm from the compass is out of the question seeing both are navigation items and both may need to be used at different times.

Maybe I will have to pull the flush mount compass out while using the GPS

cheers

Garry

[disorderly]

Is it supposed to cause a problem for the GPS or the compass?
I think a lot of boats would have these items within 3 feet of one another?
There is only so much room along the dash ...

Scott

[Dan5]

Magnetic field's mate, electrical and metalic can both have an effect on compass bearing have a look at a compass made for steel boat.Try and wave a piece of steel near your compass and watch it swing.Dan....

[Spaniard_King]

So dan what effect with the Compas have on the GPS concidering my last was only 20cm from each other and I had no ,problems??

Seesm to be a stupid spec to me, what do they expect ocean liner to be using them

Garry

[Dan5]

Yeah Gaz i don't" think" that the gps will be affected i reckon that they are just playing it safe so it does'nt interfere with the compass cos you've got metal in the locking pin and bracket hav'nt you?I don't think that they used 316 for the pin they proberbly used 304 which is magnetic but also the electrical field will have a slight induction which maybe could have an affect.I did the same as you in my last boat sounder,gps either side of the compass on the console and never realised any problem's.They could be expecting a steel yacht to be using them but that only applie's to the compass though in being sheilded.

[Spaniard_King]

Dan,

going to flush mount the unit so hopefully keep metal parts to a minimum. The new flush mount system allows for the unit to be easily removed from the dahs to be stored safely elsewhere a bit of added security in being able to remove the unit. just have to ensure minimal steel parts are used, may even go to the trouble of refabricating the mount in 316 if its magnetic

cheers

Garry

[Dan5]

What have they done put thread's in the back like the navman's?I'm getting the older 298 model this weekend i hav'nt ever owned anything Garmin before but i have used it on mackeral dory's all the other stuff i've had has either been furuno or lowrance i have also used the navman gear which is why i'm trying something differ'nt i'd like to see the new garmin stuff with the google type background it should be good i'm sure you'll post it for us.Dan..

[finga]

It's the electrical magnetic fields I'd be more worried about acting on the compass.
The see if it's going to affect you Gary just power up the GPS unit (unmounted) and move it towards the compass. You should see a distinct movement of the compass. (or vise versa)
If no movement...no worries
The same goes for the sounder as well and any electric wiring under the dash if it's supplies a high current user like bilge, anchor winch etc.
You must be getting real toey about getting the new boat on the water eh.
Cheers Scott

[Spaniard_King]

yeah Scott, you could say that still a while off before she gets wet

Garry

[trueblue]

It is the compass that will be out a bit. Radios, all electronics, electrical wiring and the like all running close to the compass can affect its accuracy.

Its not a big problem though, because good compasses can be adjusted (Look underneath the compass and you will see little bars that can be turned with a little key provided with the compass.

You have to adjust the compass with everything turned on as normal. NOTE: Compasses need to be adjusted anyway, regardles of whether or not they are set next to electronics etc. Just your steel steering mechanicsms can cause interference with the compass.

It is a bit trickey though and is best done by a professional compass adjuster, although your compass should come with instructions on how to do it.

If you do it yourself, you can go to the compass adjustment buoy in the bay where the leads are marked on the chart to fixed landmarks. Its a trickey job, but the thing to do is get it adjusted so that it reads as close to accurate in all directions. A northing adjustment will cause a slight change in the easting and vice versa, so its fiddle, fiddle, fiddle till you get it right.

However, if you choose a professional (Call your local chandlery and they will put you on to one) they will give you a certificate of adjustment accuracy.

Just remember that once adjusted with the electronics on, it won't be quite right if your turn something off.

Cheers

Mick

[3Vs]

Probably only need the compass if the GPS blows up. Just throw the GPS overboard in this instance for maximum separation.

[Spaniard_King]

Probably only need the compass if the GPS blows up. Just throw the GPS overboard in this instance for maximum separation.

Will keep this in mind.. next time I am out in your boat .. ya Bugga

[peterreb]

Just walk under power lines with a hand held compass and you will see why

[trueblue]

You must have a compass in the boat for navigational purposes in case the electronics fail. If properly adjusted and even near by the electronics etc, they will still be accurate enough to get you home if you are beyond sight of land and everything packs in which is what you need.

Up north I was coming back from a wide reef in a mates boat and we came a cross a guy who had a dead GPS and radio from an electrical fault. His engine was still running, but he had no fuses left to get his radio going and his gps had been fried.

He was completely lost and was heading for Lucinda supposedly "following the sun" instead of heading into Townsville.

Compass would have sorted him out, but he didn't have one fitted.

Cheers

Mick

[kingtin]

If you can't be arsed adjusting your compass, make a note of how the GPS affects it from true (ie Number of degrees variation from true). Then if you ever need to use your compass due to GPS failure, just add or subtract the variation (effect of your gps) to your back bearing to base.

kev