How To series - initial line marking using 3:4:5 triangle

Lee Williamsin Technical

In the first of our initial line marking videos, our How To series continues with Dave Saltman, Managing Director of Maxwell Amenity Ltd, explaining the 3:4:5 triangle method.


  • Measure out the area to determine where you should put your baseline string line and determine how and where the pitches will fit in
  • Make considerations for surrounding obstacles and give yourself enough room
  • Once you are happy with the above, put down your first string - this will be your baseline
  • It is important to get a nice tight straight line
  • Now you have your touch line or goal line, measure out the length of the line according to the size of pitch you require. Make a mark and place a peg on it to show where the corner of the pitch will be
  • To get everything square you will now have to use the 3:4:5 triangle to provide a 90-degree right angle. The bigger you make this triangle the more accurate your marking out will be
  • Using your tape measure (100m/330ft), You are best to use measurements of 30ft, 40ft and 50ft as your 3:4:5. First mark 30ft down the string line and place a peg on this point
  • From here, you will need a measurement of 50ft which is the longest angle going diagonally. Add this to the 30ft giving you a measurement on your tape of 80ft
  • Until you have the fixed point at the starting point, you are not able to mark in the 80ft mark
  • Preferably with someone's help, have them reel out the other 40ft and hold the tape at120ft on the starting point.
  • With the tape now anchored at the start and at the end, hold the tape on the 80ft mark and pull the tape nice and tight. Place your peg in the ground vertically, this now gives a 3:4:5 triangle
  • Once the 3:4:5 triangle is set up, extend a string from the starting point through the peg on the 80ft mark. Line up the string with the peg on the 80ft mark - you will need someone's help to let you know when the string is just kissing the peg
  • Once there, make sure the line is nice and tight, then run tape from the starting point and measure out the relevant length to your size of pitch on this second line
  • Making sure the tape is nice and straight, put your mark in giving you your second corner
  • Repeat the 3:4:5 triangle method on the line you have just put down to give you your third line
  • Once again keeping the tape nice and straight measure out the appropriate length and mark in your fourth corner
  • All being well you have put in two 3:4:5 triangles that are reasonably accurate, so now string in your final line and measure to check accuracy
  • You now have a rectangle and the basis for whatever pitch you are marking in

There are other videos in the How To series including:

Setting cylinder mower on cut
Pre-start checks for a ride-on mower
Pre-start checks on a pedestrian cylinder mower
Setting height of cut on a cylinder mower
Storing machines away for winter
Back-lap a pedestrian cylinder mower
The importance of using the correct sprinkler nozzle
Step by step guide to strip down a sprinkler
Step by step guide to replacing a sprinkler
Basic maintenance of a solenoid valve
Establish a wildflower area

If you require further information, Grounds training offer regular courses for Initial Sports Line Marking. Contact Carol Smith on 01902 440251

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