# how to lay out radius

Discussion in 'Hardscaping' started by treemover, Jan 19, 2014.

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1. ### wbdodgeivLawnSite Memberfrom Roanoke, VaMessages: 22

Put a 6 foot string on a longer stick. Hold stick over water so the center is where it needs to be, use string to mark radius whilst someone else holds stick.

2. ### 1idejimLawnSite FanaticMale, from State of JeffersonMessages: 11,127

I'll volunteer to draw the RP set backs in if you video you in the boat establishing the RPs. We could see which method is easiest. That'd be a hoot. Of course neither of us know the parameters of the project.

Seriously, your time and money is better spent at the drafting table than in the field.
Honestly I don't layout a slab without knowing what my hypotenuse for the square is before leaving the house. I want to drive one pivot stake, use three tapes and pull a perfect square every time. Here's an example for a 30' square. 30 x 30 = 42.42. Quick, simple, accurate every time.
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3. ### Armsden&SonLawnSite Silver Memberfrom adirondacks, NYMessages: 2,358

I like 1idejim's idea of a hippopotamus. But how would you train him to hold the line in his mouth while at the same time being perfectly in the center of the pond?

4. ### zedosixLawnSite Silver Memberfrom Eastern OntarioMessages: 2,665

Or in english, measure from one end to the other on a 45deg. angle. Very accurate, no messing up.

5. ### 1idejimLawnSite FanaticMale, from State of JeffersonMessages: 11,127

Almost. Instead of measuring a triangle, you create a triangle. It requires the use of three tapes and a minimum of two persons.

A long screwdriver or spike can serve to hold the smart end (0) of two tapes. One guy holds (0) at thirty feet and the other guy holds 42.42 at thirty feet. Tapes are pulled tight and staked. That gives you one half. Pulling thirty from the corners closes the box and you back check the hypotenuse. That's pretty simple English.

By the way, the OP stated the 100' RP is in six feet of water, not six feet in the water.
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6. ### clipfertLawnSite Memberfrom Eastern PAMessages: 204

Look into GPS construction layout equipment such as Topcon. Won't be cheap. I know you said the architect wants a radius. Is the pond a perfect radius? Did you zoom I on it from above with google maps?

7. ### OxmowLawnSite Senior Memberfrom OklahomaMessages: 480

Isn't there a way to do that with two stakes and a length of 1/4" rope? It has to do with geometry as well, but you use the amount of slack in the rope to draw the arc? Thought I've seen it done that way sometime in the past with no access to the center point.

Try this: https://www.uwgb.edu/dutchs/MATHALGO/Ellipses.HTM

The pin and string method on a larger scale.

Last edited: Jan 22, 2014
8. ### 1idejimLawnSite FanaticMale, from State of JeffersonMessages: 11,127

If you're just wanting to form a radius, dry insert some one inch pvc pipe and move it where you want it. Now the architect may have something to say after it built though.
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9. ### 1idejimLawnSite FanaticMale, from State of JeffersonMessages: 11,127

I'm not trying to be a jerk but you guys are supposed to be professional yet you're suggesting homeowner techniques. There's no drawing or specs posted to help anyone envision the site but hey, we can read the thread starter.

"doing a 'seawall' on a pond. whats a good to layout the radius? the center point is in 6' ft of water"

When I read this post I think "I know
What a sea is, this isn't hard to imagine"

Next I read "whats a good to layout the radius" I interpret this to say "I'm on my own to do the surveying on this gig" architect is laying all of the responsibilities off on the subs.

Then the op says "the center point is in 6' ft of water" I say to myself ", "something's going to leave a mark on this site". Then we find out that the RP is for a hundred foot radius. This radius point might be in 6' of water, a hundred feet out in the pond.

I know that I may be wrong since I haven't seen the site and I'm going from the ops post but? Contractors go bust daily because they took something for granted or thought that this is an easy peasy job, we can make it work. Sometimes, you can't make it work, it has to be as close to right on as humanly possible.

Your career might count on it
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10. ### Armsden&SonLawnSite Silver Memberfrom adirondacks, NYMessages: 2,358

All joking aside.... Well said..