a security door closure system for cruise ships and other similar public entrance points to prevent terrorist attack or ship take - over is needed . cruise ship passenger and ship provisioning entrance gangplanks pass through large hydraulically operated shell doors . the gangplank must be removed to close the shell door . the quick close security door system is a portable bullet resistant rapid close door system that is placed in conjunction with the gangplank or other entry system , which when closed prevents forced entry . a single lever either remotely or manually operated immediately closes the doors , which then cannot be forced opened from the entrance side .