# arc bearing

## Recommended Posts

I'm attaching a jpeg of a portion of a parcel map that I don't understand. Any input from someone knowledgeable about the angle specified on the arc in the bearing nomenclature would be appreciated.

Apparently the "basis of bearings" is the property line in the upper right hand corner of the drawing. What exactly is the relationship of "angle equals 25 degrees, 28 minutes and 44 seconds" to the "basis of bearings" line? And how is this plotted on Chief?

Is this the tangent relative to the tangent where the "basis of bearing" line intersects the arc? ( I can't think of anything else it might be.) Do the bearings refer to tangents at property corners working progressively away from the "basis of bearing" line along the arc? If so, how do you get Chief to start drawing a specified arc from a specific tangent point?

Thanks,

Tom

Or maybe this is all relative to the north arrow...? Definitely not clear to me, heh, heh.

##### Share on other sites

The delta refers to the angle subtended by that arc with that radius, using a 360 deg. circle. (So, for a right angle, you might see 90d 0' 0") However, since it looks like you can get the other points, you can just draw an arc between those points and change it to that radius (double check the calculated length), and you should be good to go. You can also check the Arc Angle in the Arc Specification DBX if you change the Number Style appropriately.

##### Share on other sites

Thanks Richard. This is Tom Papa by the way. How's things? David's house is holding up as well as can be expected with eight kids and a dog having the run of the place, heh, heh.

I've actually tried connecting the dots and reforming the arc to the specified radius but that function seems to have tendency to change the location of the arc, and it's not behaving when I try to move it to the correct location. Doesn't seem like you can reorient it by cartwheeling it around one of the end points, if you know what I mean. The hand drawn plot plan was from the county records and has some obvious errors. Makes you wonder how accurate all those old surveys actually are.

##### Share on other sites

Hi Tom! Hope David has a woman in his life now to help manage those kids!

Anyway, to get the arc to stay, LOCK the chord first, after getting the end points in the right place. Then you can change the radius without moving the end points. Alternatively, you COULD cartwheel it, but you need to set the behavior to Rotate Around Current Point in CAD Edit Preferences, and it's not very exact if you're eyeballing it.

##### Share on other sites

Thanks for the tip Richard. I'll have to think on this and fool with it a bit but these are two approaches I haven't tried. I also have to change the length of the arc which may be a problem, just sitting here thinking about it.

I'm working down in Big Sur these days for the fellow who introduced me to David so I don't have a lot of time to fuss with Chief or even get online. David has plenty of help these days so no worries there.