Need help projecting a point

The bearing is S88d15'30"E which is an azimuth of 91d44'30"

To answer your question, IF the bearing and the plat you show is on SPC Grid North and IF your data collector is on SPC Grid North then you can get there using the GRID azimuth and distance.

If I knew how, I would have UNDERLINED both of those IF's.

James

Drilldo, post: 399367, member: 8604 wrote: http://imgur.com/a/JybrW

I am not a land surveyor and this type of thing is new to me.

If I want to move this point say 500' east and maintain the same distance (467') from the north line would I just need to have the Azimuth 88 deg 15 min 30 sec and the distance 500'?

The plat says the distances and bearing are based on the state plane system and that is what I am working with in my data collector. So could I just go to cogo and create a point with bearings based on grid?

I understand it mathematically but I am not sure what exactly the bearing I am seeing on the plat mean.

I need to figure this out or we can not work tomorrow. The surveyor that made this plat doesn't work weekends and I can't get any help from him until Monday.

From the information presented sure you can convert the bearing to an azimuth (91-44-30) and do that but understand you are basically owning any and all consequences that may occur IF

Drilldo, post: 399367, member: 8604 wrote: http://imgur.com/a/JybrW

I am not a land surveyor and this type of thing is new to me.

If I want to move this point say 500' east and maintain the same distance (467') from the north line would I just need to have the Azimuth 88 deg 15 min 30 sec and the distance 500'?

The plat says the distances and bearing are based on the state plane system and that is what I am working with in my data collector. So could I just go to cogo and create a point with bearings based on grid?

I understand it mathematically but I am not sure what exactly the bearing I am seeing on the plat mean.

I need to figure this out or we can not work tomorrow. The surveyor that made this plat doesn't work weekends and I can't get any help from him until Monday.

Yeah at an elevation of 3422 feet i, not sure I'd advise taking this on without your surveyor unless your accuracy tolerances are real loose.

Accuracy requirements are about 5'. Not super critical. Basically I am just doing some geological testing at a well site location. We did tests at the well stake as shown on the plat and the tests determined it to be a bad location and the client wants to move it east and test again. They want us to do it tomorrow and the surveyor doesn't work weekends. Me and my 5 man crew are here on location out of town ready to work and need to figure out how to do this test at the new location without the help of the surveyor or we can not work tomorrow.

Jaro you have a PM.

I would trust my handheld GPS for geology purposes.

A Harris, post: 399391, member: 81 wrote: I would trust my handheld GPS for geology purposes.

While they are likely accurate enough for what we need to do that still doesn't solve my problem of finding this point. There is a well stake we did testing at yesterday and the client deemed it no good and wants us to move east and I am not exactly sure how to find this east point. I mean I know how to measure distances and bearings in the GPS but I am not sure that the bearing displayed on my GPS matches the bearing shown on the plat.

I am not building anything or leaving anything permanent on the ground. I just need to do one day of work at the new site and I don't want to do this testing in the wrong spot and have it be worthless. At the same time I don't want to have to sit at the motel tomorrow and do nothing waiting on the surveyor to figure it out Monday. The client has kind of put us between a rock and a hard place on this one.

We have RTK primarily because the relative elevations of our testing are important. It isn't the end of the world if our actual elevation is off but we need sub-foot elevations for each of our test points relative to each other.

If you're willing to take on any potential liability you have already been given the answer, I personally would spend that day in the motel looking for a surveyor that accented my needs.

BK9196, post: 399393, member: 12217 wrote: If you're willing to take on any potential liability you have already been given the answer, I personally would spend that day in the motel looking for a surveyor that accented my needs.

The part that confuses me in the answer is this

"The bearing is S88d15'30"E which is an azimuth of 91d44'30"

The plat says "The bearings and distances are based on the Texas Coordinate system of 1927, central zone."

If my job in the data collector is set to that system and I go to cogo, compute point, bearing and distance and then set the start point to the existing well stake, the azimuth to grid 0,the azimuth(grid) to 88 15 30 and the distance to 500 feet I should be good?

If I am wrong there is no real liability other than a wasted day of my time. What would happen if I was wrong is the mark I put where I centered my tests would not match up with the surveyors stake he will place Monday and they would tell me to redo it.

My employees get guaranteed pay when we are on the road regardless if we work or not and I have to pay for the motels and their per diems either way. It really makes sense to try and do it but I want to do it in the most educated manner possible.

The surveyor works for the client just like I do. I do not pay him so he really does not care about my problems.

Drill your test hole
When the surveyoy shows up have him locate and provide an elevation

A Harris, post: 399397, member: 81 wrote: Drill your test hole
When the surveyoy shows up have him locate and provide an elevation

I can't. They want it in the right spot. I can get an X,Y and elevation myself that is no problem. I have control points in the area and RTK. Getting an accurate position of what I do isn't my problem.I do that part on a daily basis. My problem is locating this point in the correct spot from the information on the plat.

Normally the client provides me with an X,Y. I set up on or calibrate to a control point and go find it. That is easy. What is confusing me is the moving 500' east from a known X,Y and maintaining the 467' from the north line.

If your data collector is set up in the same datum as called for on the plat and the known position is good you could just forgo the cogo and stake out to your existing reference point and flip the bearing around 180. When your arrive at the desired location the DC should be telling you to go 500' on the reverse bearing. The mapping angle for that projection should get you on the money if all the given parameters are true and you're working off something tighter than an autonomous solution.

Williwaw, post: 399401, member: 7066 wrote: If your data collector is set up in the same datum as called for on the plat and the known position is good you could just forgo the cogo and stake out to your existing reference point and flip the bearing around 180. When your arrive at the desired location the DC should be telling you to go 500' on the reverse bearing. The mapping angle for that projection should get you on the money if all the given parameters are true and you're working off something tighter than an autonomous solution.

Thanks. I know how to do this and have done something similar before. My test locations are set up on a grid that I build. Sometimes I have to move one and I do so by staking out the point and then using the bearing and interval I built the grid on.

I guess my confusion on this whole deal relates to if the 88 15 30 is the bearing I can use like that. When JaRo said it is an azimuth of 91d44'30 it confused me more. I don't really know how to read survey plats.

Bearings and azimutha are two ways of stating the exact same thing and are easily switched if you have a basic understanding. The bearing stated sounds an awful lot like 'east' plus or minus the appropriate mapping angle to compensate for convergence on the defined grid projection. The grid ground scale factor in 500' is negligible.

A bearing of S45dE would be the same as an azimuth of 135d. It is 45 degrees east of due south. Your bearing is S88d15'30"E so it is 88d15'30" east of due south or for general directions, just a hair south of due east.

South is an azimuth of 180, you are 88d15'30" less than that. This calculates to an azimuth of 91d44'30".

James

Drilldo, post: 399403, member: 8604 wrote: Thanks. I know how to do this and have done something similar before. My test locations are set up on a grid that I build. Sometimes I have to move one and I do so by staking out the point and then using the bearing and interval I built the grid on.

I guess my confusion on this whole deal relates to if the 88 15 30 is the bearing I can use like that. When JaRo said it is an azimuth of 91d44'30 it confused me more. I don't really know how to read survey plats.

Bearing is from south measured 88-15-30 counterclockwise towards east. It is 1-44-30 clockwise from east. The north azimuth is 180 (-) 88-15-30 equals north azimuth of 91-44-30 (measured clockwise from north). Depending on how your controller is set up you calc your desired point from the original point, enter either bearing or azimuth. Most Surveyors prefer bearings.

Thanks guys. I get it now. JaRo I calculated it myself using the correct azimuth and got the same answer as you.

Now I get to work tomorrow in 7 hours.

My understanding (which could be wrong): Measure the bearing and distance between at least two known points (known on the plat and known on the ground). See if the bearing and distance of what you measure matches the plat. If they do, then you can just stakeout the point in question. If they don't, then you're going to need to do a translation, rotation and scale first.