The depth and width of the ditches surrounding a bowls green are set out by the relevant bowls authorities.
The current regulation state that ditches can be between 200 mm and 380 mm wide, and that the ditch depth can be between 50mm and 200 mm deep.
Within the above limits there must be uniformity regarding the depth and width on all four sides of the green. It is accepted that as a result of regular top-dressing the surface of the green will rise in relation to the ditch boards.
If the ditch board is more than 10 mm below the surface of the green the boards must be lifted, as the grass surface becomes spongy and could cause bowls to fall into the ditch.
The ditch Board should be slightly angled away from the edge of the green at between 10 to 20 degrees from the perpendicular.
There is no set angle laid down to set ditch boards, but the angle should not be such that if a bowls falls into the ditch, it should not be able to hit the ditch board on its way to rest on the ditch surface.
Ditch Surface
It must be a holding surface, and free from anything that may damage the bowl.