Gap compression guides for shipping containers

A method of preventing relative movement between two shipping containers located in two adjacent columns of a stack of containers on a cargo ship and separated by a gap, the method comprising:

• placing a compression guide at least partially in the gap, the compression guide including:
• a spacer having a first side and a second side opposite the first side, the spacer having a width between the first side and the second side;
• and
• one or more attachment mechanisms adapted for partial insertion into a hole in a casting of a container or flat rack;
• each of the one or more attachment mechanisms being located on the first side and connected to the spacer,
• wherein the width of the spacer is variable,
• wherein the width of the spacer is actuatable manually,
• wherein the spacer includes a lead screw mechanism configured to transform rotation movement into linear movement and a wedge mechanism coupled to the lead screw mechanism and configured to transform the linear movement into lateral movement.