By default, grommets are roughly evenly spaced along the edge. If this is not what you want, you must supply alternate spacing instructions in the notes field when filling in your custom tarp order.
When you specify the number of grommets for each edge, the system automatically calculates how far apart each grommet will be. The distances shown are from the center of the grommet to the center of the adjacent grommet. Please note that these distances are just approximations, some grommets may end up being closer or farther apart than what is indicated.
When grommets are specified, we assume that the initial grommets will be set on the ends of the specified edge. The centers of these end grommets are always one inch from the edge of the tarp as shown in the following image.
By default, opposing grommets may not exactly line up. That is, if you fold the tarp in half the grommets on one side may not align with those on the other side. If this is necessary, please add a note about this. Similarly, if you order two tarps that are both ordered with the same grommet spacing it is unlikely the grommets from one tarp will align with those of the other unless we are specifically told that this is necessary.
Note that when entering the number of grommets, the end grommets are "double counted" since these grommets are considered to exist on each adjacent edge. For example, if you request 5 grommets on each of the four edges, you really only get 16 grommets, not 20, since the corner grommets are counting toward the total on each edge.
In terms of the ideal grommet spacing, this depends on the tarping application. If the tarp will be exposed to high winds, such as tarps used for utility trailers, it is a good idea to request more grommets to better distribute the load on each grommet. Nevertheless, remember that the grommets are only useful if you have a place to fasten them. If you have a fixed number of anchor points you generally want to try to align your grommets with these tie-down locations.
We don't charge extra for our standard grommets unless the number of grommets becomes excessive (generally more than one grommet per 18 inches or so).
If you are attaching the tarp to a frame (such as a doorway, carport, window, garage, etc.) it is a good idea to start by deciding where the fasteners will go into the frame. Generally, the length of the tarp will be 2 inches greater than the distance between the fasteners on opposite sides of the frame.
Sometimes it may be necessary to position grommets or snaps, etc. at very precise positions. We can usually accommodate this but only if you supply us with a diagram that shows exactly where you would like the grommets to be set. The diagram should show the number of inches from each edge where the grommets are to be placed. If you are ordering several tarps and you are planning to join them together using grommets you need to advise us of this so that we can ensure that the holes are positioned to allow for this.
Our standard grommets are stainless steel and have an outer diameter of 7/8 inch and an inner diameter of 7/16".
Larger stainless steel grommets are available having an outer diameter of 1" and an inner diameter of 9/16" are available at no extra cost.