Adjusting an in-RV compass
Jctaylor74
for adjusting, i.e., "compensating", seem overly complicated. The directions
say to find streets which (a city map indicates) run north, south, east and
west, then drive along the street(s) turning the little adjustor "shafts" until
the "N" )or "S" or "E" or "W" is under the red line on the lens. The
instructions also say that "compensation is considered satisfactory if compass
is within three calibarations (+/- 15 degrees) at all four cardinal points."
(They also say that when the compass is at "maximum compensation", it may not -
depending on certain circumstances - be accurate!) Is this as good as it gets?
Is there an easier, yet accurate, way to calibrate the compass without
cruising the city? I'm sure not going to be hunting down less-trafficked (HA!)
"true" north-south, east-west-running streets, lining up a "helper" (this is
obviously a two-person job), then driving around twisting little adjustor
shafts with a dime unless I'm *very* sure it's going to be worth it. I would
appreciate suggestions; thanks.
dtbla...@worldnet.att.net
>
> I bought a small ("Airglide" brand) compass for the rig, but the instructions
> for adjusting, i.e., "compensating", seem overly complicated.
> shafts with a dime unless I'm *very* sure it's going to be worth it. I would
> appreciate suggestions; thanks.
I had no great problems adjusting one of those things.
However, I found the accuracy to be as reliable as a
newcaster's weather report. I never knew for sure if the
reading was correct unless I already veritably knew the
true compass direction. Kind of makes the whole thing
pointless.
--
==============================================
Dale
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DsrtTravlr
Mine has four levels of functioning:
1. Key off
2. Key on
3. Key on and engine running
4. Engine starting
It reads four different things sitting still during the four phases.
I have set it to be accurate (?) while driving.
I have to ignore it at all other times.
I gave up on getting it adjusted on NSEW streets as in the directions. I got a
REAL compass, and using that for orientation, and went to a large empty parking
lot with no overhead wires.. Don't forget to leave the engine running when you
go outside and away from the MH to get an accurate reading on your pocket
compass. If you have a helper, turn 90 degrees, and readjust. Do this a few
times.
Even then, I think I only got it somewhat close.
It sure looks good, though. Even has a night light.
Steve
Illigitimi non carborundum.
GBinNC
>I have one of those. It was an experience trying to get it set.
><snip description of adjustments>
>
>Even then, I think I only got it somewhat close.
>
>It sure looks good, though. Even has a night light.
OTOH, how close does it really need to be?
We enjoy exploring back roads in the boonies. If I get "turned around"
and don't know which way I'm headed, as long as the compass gives me a
general idea of whether I'm headed one way or the other, that's all I
really need to know. I couldn't care less whether it says 270 or 280,
or SSW or WSW.
I'm not exactly navigating by the thing; that's why I have maps and
Street Atlas. I just want to know in general which way I'm facing so
I'll know if I should turn around.
GB in NC
William Miller
"West"
GBinNC <GBi...@yahoooo.com> wrote in message
news:3904b2de....@netnews.worldnet.att.net...
George E. Cawthon
>
> I bought a small ("Airglide" brand) compass for the rig, but the instructions
> say to find streets which (a city map indicates) run north, south, east and
> west, then drive along the street(s) turning the little adjustor "shafts" until
> the "N" )or "S" or "E" or "W" is under the red line on the lens. The
> instructions also say that "compensation is considered satisfactory if compass
> is within three calibarations (+/- 15 degrees) at all four cardinal points."
> (They also say that when the compass is at "maximum compensation", it may not -
> depending on certain circumstances - be accurate!) Is this as good as it gets?
> Is there an easier, yet accurate, way to calibrate the compass without
> cruising the city? I'm sure not going to be hunting down less-trafficked (HA!)
> "true" north-south, east-west-running streets, lining up a "helper" (this is
> shafts with a dime unless I'm *very* sure it's going to be worth it. I would
> appreciate suggestions; thanks.
What's wrong with looking at a city map to find a north/south street?
You don't adjust the compass while you drive, you just park parallel to
the rode and then do the adjusting.
If you want to be accurate, you need to mark a true north/south line
anywhere you can, e.g., a street in your subdivision, your driveway, or
a nearby parking lot. You are a boy scout and know how to find the
north star, right? If not get a boy scout to show you how to find the
big dipper and the north star. Since the north star is quite high in
the sky and you need to line up two spots you will need at least a 10
foot pole. Mark a spot on the ground, put you head there, and have your
partner move the pole around (hold straight up with one end on the
ground) while you line it up with the north star. Then mark the
position of the pole and draw a straight line to the spot where you put
your head. Put a front tire and a rear tire on the same side on the
line.
Now adjust the compass until is says 0 degrees (North).
You do realize that magnetic north is not the same as true north? So,
as you move about the U.S. the compass will always be a little off.
Takes a long time to explain but takes about 3 minutes to do.
Scott Leahy
>I bought a small ("Airglide" brand) compass for the rig, but the instructions
>for adjusting, i.e., "compensating", seem overly complicated. The directions
>say to find streets which (a city map indicates) run north, south, east and
>west, then drive along the street(s) turning the little adjustor "shafts" until
>the "N" )or "S" or "E" or "W" is under the red line on the lens. The
>instructions also say that "compensation is considered satisfactory if compass
>is within three calibarations (+/- 15 degrees) at all four cardinal points."
>(They also say that when the compass is at "maximum compensation", it may not -
>depending on certain circumstances - be accurate!) Is this as good as it gets?
> Is there an easier, yet accurate, way to calibrate the compass without
>cruising the city? I'm sure not going to be hunting down less-trafficked (HA!)
>"true" north-south, east-west-running streets, lining up a "helper" (this is
>obviously a two-person job), then driving around twisting little adjustor
>shafts with a dime unless I'm *very* sure it's going to be worth it. I would
>appreciate suggestions; thanks.
It's not worth it. Even the best compass will differ from true North
(The "North" on a map) due to variance in the alignment of Earth's
magnetic field. It varies according to where you are. Just look at a
map and find a good North-South/East-West street and turn the knobs
until the compass agrees with the map alignment and then forget it.
The compass will be accurate enough for rough navigation on any road,
which is all you can expect without taking magnetic variance into
account and correcting according to location.
If you want better accuracy, get a GPS setup and it will tell you
pretty near exactly where you are, and with the right software,
exactly where to turn to reach your destination.
Scott
sle...@ohnayamspay.ridgenet.net
(For email, ixnay the igpay atinlay)
Pete Dumbleton
back road or parking lot that has, say, N/S orientation with a right angle
E/W orientation per a fairly good map. I just align the vehicle with the
road (or whatever) and make my adjustments when it's not moving but the
engine is running, moving the vehicle to the various headings as needed.
After I've got it done, I move the vehicle to each of the four points to
check it. If I'm satisfied, then I move it to each point one more time,
turning on various electrical stuf, headlights, radio, heater blower,
etc., to determine what, if any, effect it has on the compass, trying to
keep mental notes. Hopefully, if headlights, wipers and blower have a
significant effect on one set of cardinal points, I'll remember to
consider that if I find myself in the rain at nite.
Obviously, this may be overkill when all you really want to know is "Are
we still headed north?", but I learned this stuf in boats when you rely on
the compass more heavily because the white lines down the middle have
usually washed away...
Trouble is, if you don't least at check it, it's possible for the compass
to be *way* off, depending on where you mount it and what magnetic (i.e.,
speakers, steering wheel) and electromagnetic (power lead in dash to
cigarette lighter) influences exist in your vehicle, plus whether or not
the compensating magnets were set in the factory or moved in shipping,
handling or installation. I've found mounting places where the dang thing
will point E when the vehicle is headed E, N or S...
On 24 Apr 2000, Jctaylor74 wrote:
> I bought a small ("Airglide" brand) compass for the rig, but the instructions
> for adjusting, i.e., "compensating", seem overly complicated. The directions
> obviously a two-person job), then driving around twisting little adjustor
KJ6CO
in all directions, but when I went out in Barnegate Bay and followed a compass
course, I ran onto a mud bar.
Turns out the steering wheel was magnetized, and greatly affected the compass.
The compass moved violently when the steering wheel was turned. Suspect the
wheel became magnetized when it was arc welded in manufacturing.
Had a hard time deguasing it.
Jerry
Pete Dumbleton
boat on Tampa Bay for some fishing, with a serious, properly compensated,
marine compass. He took headings from the canal to the marker, and ran the
opposite heading back from the marker to the unlit, unseen canal entrance.
We all sat for a while, beached on sandbar, marveling at the newly
discovered effects of a steel beer can sitting on the center console near
the compass.
BTW, an influence above or below the compass will often have more effect
than one in the same horiz plane.
My truck's steering wheel is too close to my compass, so it's only
accurate when I'm running straight ahead, but I know that and don't look
at it on curves.