topic Re: COGO a Feature Class in ArcGIS Pro Questions

COGO a Feature Class

MHO_Harbors — Fri, 23 Jan 2026 06:39:26 GMT

Hi,

I'm using ArcGIS Pro 3.6.1 and I'm trying to COGO some survey points to create an easement. Entering the traverse points is fairly easy, we use South Azimuth in Hawai`i. The issue I am having is establishing the POB. Here is what I am doing:

1) The easement begins with "beginning at the north corner of this parcel of land, the coordinates of said point of beginning referred to Government Survey Triangulation Station "NAWILIWILI" being 2,336.47 feet South and 1,627.19 feet West, thence running by azimuths measured clockwise from true South..."

2) I open Pro and add the NGS Datasheet Feature Service. I have found the NAWILWILI geodetic control point, here is the datasheet.

2) Then in Catalog --> Databases I create a polyline feature class titled “KN_3”. I give it the projection for Kauai, NAD 1983 HARN StatePlane Hawaii 4 FIPS 5102 (US Feet) . Then I run Enable COGO on it.

3) I then go to the ribbon and open Project --> Options --> Units --> Distance Units and change it to US Survey Foot. Under Angular Units I select DMS.

4) Under Map Properties --> Coord System I keep it at what the NGS Datasheet Feature Service is, NAD 1983 (2011).

5) Then I activate Ground to Grid Connections.

6) My next step is to open Modify under Edit and select Traverse. I set the start point on the NAWILIWILI control point as seen in the red dot on the triangle below. I enter SAz, 0-0-0, distance 2,336.47'. I then enter SAz, 90-0-0, 1,627.19'.

This is where it gets off. These two survey points should set the POB for the easement. The problem is the POB is in the ocean and not where it should be:

Where it should be is somewhere near this circle:

I'd really appreciate it if somebody could give me a step-by-step on how to do this. Thank again.

Re: COGO a Feature Class

ZenMasterZeke — Fri, 23 Jan 2026 17:23:15 GMT

Not sure, I get roughly the same in a quick Google measurement, but here are some ideas...

Turn off ground to grid. You're basically measuring flat ground/water at this point. Probably doesn't change anything, but worth a try.

The measurements are wrong. 2336' W, not E, then 1627' S puts you closer to where you should be.

Sometimes surveyors start with the POB, then reference back to a known marker. Try starting with the presumed POB and go backwards. Or start with your marker and draw the parcel in reverse, beginning with the last traverse.

I've seen plats where surveyors start in one direction, say counter clockwise, then halfway through switch to clockwise. Maybe needless to say, but this doesn't work.

Re: COGO a Feature Class

MHO_Harbors — Fri, 23 Jan 2026 18:09:20 GMT

Thanks for your reply. I did think maybe they mixed up the West/South and although it gets closer it's still off. Sounds like what you say is correct, I'll add it to the metadata. Appreciate your help.

Re: COGO a Feature Class

ZenMasterZeke — Fri, 23 Jan 2026 19:20:23 GMT

If the two POB points are relatively close, the error could be in a different coordinate system, or measured by something other than a US Survey foot. It's possible that whoever drew up the traverses didn't use the same cs and/or units you did, particularly if the document is older than current ones. From a deep (3") 🙃 dive into Google:

Kauai primarily uses NAD83 UTM Zone 4N for geospatial data (digital elevation models, GIS mapping), with coordinates generally falling between latitudes 21.8°N–22.3°N and longitudes 159.3°W–159.8°W. For land surveying and local mapping, the State Plane Coordinate System Zone 4 (SPCS83, Code 5104) is commonly used.

Primary Coordinate Systems for Kauai:

UTM Zone 4N (NAD83): The standard projection for technical, GIS, and mapping data on Kauai.
State Plane Zone 4 (NAD83): Frequently used for parcel, cadastral, and local surveying, often in U.S. Survey Feet.
Geographic (Latitude/Longitude): Based on the WGS84 datum for GPS, or NAD83 for state GIS data.
Old Hawaiian (1927): Occasionally found in older surveys.

Commonly Used Projections/Codes:

NAD83(PA11) / UTM zone 4N: EPSG:6627 (or similar NAD83 variants like 26904).
NAD83 / Hawaii Zone 4 (ftUS): EPSG:3564.

For most mapping applications in Kauai, this PDF from the Hawaii Department of Land and Natural Resources provides a direct reference for the state's coordinate systems.

Re: COGO a Feature Class

MHO_Harbors — Fri, 23 Jan 2026 20:09:59 GMT

Let me give it a try, thanks.

Re: COGO a Feature Class

MHO_Harbors — Sun, 25 Jan 2026 04:10:31 GMT

No idea how to do this. I tried changing projections:

1) Changed Map projection to NAD 1983 (PA11) UTM Zone 4N because that is what it said in the data sheet when they placed the NAWILIWILI control point.

2) Go to Project --> Options --> Units change Distance Units to Foot_US and Angular Units to DMS.

3) The I open Go To XY and put in the coordinates

Latitude: 21 57′24.59560′′ N

Longitude: 159 21′09.30476′′ W

And drop a pin there.

4) Then I change the Map projection to NAD 1983 HARN StatePlane Hawaii 4 FIPS 5104 (US Feet). Pin stays in the same place.

But whenever I change the map and feature class to different projections the COGO shoot for the POB never lines up. Sometimes I'll change the Map projection to something different than the feature layer and vice versa. Feature layer either goes far off into he ocean or exact same place as above.

I'm thinking UTM and Northings and Eastings are a possible answer, but don't know the SOP to make it happen.

Really hard GIS problem when COGO is usually quite easy.

Re: COGO a Feature Class

ZenMasterZeke — Sun, 25 Jan 2026 23:12:39 GMT

I ran a SAz traverse of S90, 2336 ft, SAz 0, 1627 ft. and got the result below. Is that what you're looking for? Map, point and line all in NAD 1983 (PA11) UTM Zone 4N (wkid 6634)

Re: COGO a Feature Class

ZenMasterZeke — Sun, 25 Jan 2026 23:15:02 GMT

Also the datasheet for your survey marker says it was lost, and current location is estimated, with a 10' error margin, so take that into account

Re: COGO a Feature Class

MHO_Harbors — Mon, 26 Jan 2026 19:21:28 GMT

You make a good point about it being lost. I also switched the S/W traverse and I got what you got. Fortunately I could georeference the location of the traverse on a sheet we have, but I am trying to solve this (as GIS Analysts we want to be able to solve any issue given to us). But when I reverse the S/W it's still off. In the image below you can see where the POB is and where it should be (the pin):

Off by about 300'.

Re: COGO a Feature Class

ZenMasterZeke — Mon, 26 Jan 2026 22:34:43 GMT

Well, all I can think of is that the measurements are wrong, either in the traverse, to marker location, or both. If you have the POB from the georeference, run a reverse transverse to the marker and/or with just the given measurements to see what that gives you.

Re: COGO a Feature Class

MHO_Harbors — Tue, 27 Jan 2026 04:15:12 GMT

Yep, I think you are right. Here is what I get when I input 180-0-0 SAz 2336.47 and 270-0-0 SAz 1627.19 from the pin as the Set Start point:

You can see it is way above and to the left of the marker. Even when I go the other way it gets close bit still off. I believe it was shot wrong. Thanks again!