News:

Welcome to the largest gathering of ARIMA boat owners anywhere. We are a forum based gathering of Arima Boat enthusiasts that like to pleasure cruise, fish, camp, and hunt. While Arimas are centered in the PNW, we have members across the globe. It is 3/4's water after all. Lurk, join up, and post about your Arima upgrades, family trips, and of course, your fishing exploits. Just remember to add photos whenever possible.

Main Menu

Magnets on Micro SD Slot Door

Started by jetdoctor, September 20, 2016, 11:57:21 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

jetdoctor

I was looking for a good place to mount my Garmin 54 DV in front of the helm, and noticed that it caused the compass to change it's heading by 30 degrees.  Looking at the unit, I see that the door for the micro SD slot has a magnet to hold it shut.  I would pose the question to Garmin--"what were you thinking? :hoboy:" but most of the chart plotter/FF combos are this way.  I had wondered why the P.O. mounted the FF on the right side, and now I understand.
I see lots of people with chart plotters etc. by the helm, which is also the logical place for a compass.  This makes me wonder if I can just compensate the compass, or am I missing something?  I suppose that if nothing else, it might be something for someone else to consider when locating a GPS.  Over 10 miles, 30 degrees is a large error.
Cheers,
Doug

Kimbrey

That's a lot of error.  To me compass adjustment is a voodoo art.  Last July we went through a compass "swing" on the new rig that the company I work for put together.  I've been through this many times through the years but I still consider it a voodoo art.  The adjuster had me steer the boat through many of the compass points recording error with each point.  After adjusting the large iron spheres on each side of the compass we went through the process again and then after that which is the voodoo part to me he positioned a couple of magnets by the compass.  Back to the swing on the points again.  From there he filled out the "compass card" recording the error that I would see at various courses.

Sooooo if you attempt to adjust the error out make sure you look at the error through the various points of the compass.

I've read about compass adjustment, researched it, Googled it, Binged it and it's still Voodoo to me.

Kim
2005 Sea Legend --Sold--replaced with 26' Duckworth—Sold—replaced with 28' Farallon Walkaround

milos dad

Quote from: jetdoctor on September 20, 2016, 11:57:21 PM
I was looking for a good place to mount my Garmin 54 DV in front of the helm, and noticed that it caused the compass to change it's heading by 30 degrees.  Looking at the unit, I see that the door for the micro SD slot has a magnet to hold it shut.  I would pose the question to Garmin--"what were you thinking? :hoboy:" but most of the chart plotter/FF combos are this way.  I had wondered why the P.O. mounted the FF on the right side, and now I understand.
I see lots of people with chart plotters etc. by the helm, which is also the logical place for a compass.  This makes me wonder if I can just compensate the compass, or am I missing something?  I suppose that if nothing else, it might be something for someone else to consider when locating a GPS.  Over 10 miles, 30 degrees is a large error.
Cheers,
Doug

Doug:  I have a Garmin 55DV, which is very similar to your 54DV.  In the setup instructions, Garmin suggests a separation distance from the compass to the Garmin.  My compass is mounted left of the helm, close to the windshield, while my 55DV is mounted to the right of the helm, close to the stbd side window.  I have not noticed any compass deviation with the 55DV mounted on its bracket. 

If I had purchased a wider screen (7 or 9"), Garmin specs would have me mount the unit on the port side of the boat.

M D
Rick
87 Sea Hunter with 94 Honda 45
2009 6 hp Merc kicker

jetdoctor

Compass adjustment is a kind of black art.  I have seen it done several ways.  We hired someone years ago who had a fancy sun compass.  Then you have to deal with local anomalies etc. so compasses can be inaccurate at best.  Luckily, we now have GPS, and know where we are within a few feet.  Magnetic compasses are probably not needed except for a backup.  Dead reckoning is still necessary if you go offshore though--electronics can fail. 
The compass on the SR is right in front of the helm, presumably where one would mount a chart plotter.  It is also around all of the electric wiring of the boat. 
Maybe I should move the compass?
Cheers,
Doug

Yachter Yat

#4
Jet:

    I custom fabricated an aluminum bracket for mine.  It is screwed to the lower inside part of the dash.  Drilled it so that my Ritchie Helmsman bracket is bolted to it and allows the compass to hang just below the dash, under the steering wheel.  Not in the way and no apparent interference ever noticed.  Not only eliminates interference problem, but freed-up the dash as well.  IMO, it's the best place for it. 

   I agree with you with regard to having a compass on board; if for nothing else than having a backup.  I honestly think anybody traveling offshore should learn a bit about dead reckoning.  Funny, to this day I still use mine when we go out to the Isles of Shoals off the coast of N.H.  Every time we head back in to Portsmouth, I glance down to see which way to start running. (ha) 

Yat

History is not the past; it's the present, as we all carry it with us......James Baldwin    
16 SC/Honda 60  (sold)

Kimbrey

2005 Sea Legend --Sold--replaced with 26' Duckworth—Sold—replaced with 28' Farallon Walkaround

HemiGTX

#6
I suspect that little magnet on the SD slot door is inconsequential compared to the RF energy emanating from the MFD.

But...I'm no expert on such things.
AKA: "The guy who fishes with Nicole"

First Cabin

I mounted my compass with Velcro behind my fish finder.  Should it be needed, I pull it off the Velcro and place it in the center windshield area where I usually find the least interference.  I like that I can move it around and check for magnetic interference.
First:  1982 15' SeaHunter, Yamaha 70 2-stroke, Yamaha F6
Second:  1987 17' SeaRanger, Merc 90 2-stroke, Yamaha F8
Current:  2002 17' SeaChaser, Yamaha F100, Yamaha T8

fishmiester

Another thing to check is the setup menu on your chart plotter. My Lowrance was way off compared to the compass but it was set to true north instead of magnetic north. Now they are very close.
If it swims, Ill  chase it
84 17' Seachaser, 2010 90hp Tohatsu tldi, BF15 Honda Custom welded kicker bracket.#lovethisboat

GregE

Quote from: HemiGTX on September 22, 2016, 05:31:52 PM
I suspect that little magnet on the SD slot door is inconsequential compared to the RF energy emanating from the MFD.


Yep!!

Remember also your radio mike- if it has a speaker built in it also has a magnet
Greg
2005 SL 22 Honda 225 Kodak II
http://www.sagecreekforums.com/phpforum/index.php
Sold:Osprey 26 LC Kodak;  Arima SR 19 HT, Arima SE 16 WeeBait; SH 15 WeeBoat; SR 21 NoBait;  SL 22 ReBait

jetdoctor

The radio microphone, the radio speaker, and Chart plotter, all have magnets.  Most of the electronics companies tell you to mount their unit 30" from a compass.  In practice, this rarely happens.  I am not sure what kind of magnetic fields that the unit will produce.     
While it would seem that a compass is not necessary with all of the electronics, they still have their place.  I was going to move the compass, but have since rethought that decision.  Most people run with sonar and the chart up.  It is really hard to follow a track this way (some GPS units have a guidance page).  Setting a course with a compass saves a lot of wandering around, fuel, and reduces the possibility of hitting something.  IMHO, any trip out of sight of land should start with a paper chart, a pencil, and some parallel rules :twocents:.
The true north, magnetic north point is a good one.  True north is used when around the north pole (think 80N+ latitudes).  It is odd that it would be the default setting.  I will certainly check that on my unit.
When I get the unit powered up, I will try to find a good position to mount it.

Cheers,
Doug

milos dad

Quote from: jetdoctor on September 24, 2016, 10:49:12 PM
The radio microphone, the radio speaker, and Chart plotter, all have magnets.  Most of the electronics companies tell you to mount their unit 30" from a compass.  In practice, this rarely happens.  I am not sure what kind of magnetic fields that the unit will produce.     


Doug, thanks for posting the setback distance.  I went and checked the specifications from Garmin, and the 50 series setback distance is 29.5", but the 40 series is only 8".  I must have mis-read the instructions, as mine is located more than 8" away but less than 29.5".   I will have to check out the readings of the boats compass, a hand held compass and the gps, and see if the readings change when triggering the radio mic.

M D
Rick
87 Sea Hunter with 94 Honda 45
2009 6 hp Merc kicker