private void port_forward_checkboxActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_port_forward_checkboxActionPerformed
        //If the port middle and port forward checkboxes are checked.
        if (port_middle_checkbox.isSelected()==true && port_forward_checkbox.isSelected()==true)
        {
            //Disable port aft checkbox.
            port_aft_checkbox.setEnabled(false);
        }
        //If the port aft and port forward checkboxes are checked.
        else if(port_aft_checkbox.isSelected()==true && port_forward_checkbox.isSelected()==true)
        {
            //Disable port middle checkbox.
            port_middle_checkbox.setEnabled(false);
        }
        //If the port middle and port forward checkboxes are checked and unchecked respectivly.
        else if(port_middle_checkbox.isSelected()==true && port_forward_checkbox.isSelected()==false)
        {
            //Enable port aft checkbox.
            port_aft_checkbox.setEnabled(true);
        }
        //If the port aft and port forward checkboxes are checked and unchecked respectivly.
        else if(port_aft_checkbox.isSelected()==true && port_forward_checkbox.isSelected()==false)
        {
            //Enable port middle checkbox.
            port_middle_checkbox.setEnabled(true);
        }
        //If none of the above is true.
        else
        {
            //Pass.
        }
        //Enables the relevent fields for the chosen vessel configuration.
        vesselConfigurationSetup();
        //Enables the height from the ocean input fields if the corresponding downrigger location is chosen.
        OceanHeightTextfieldEnablerSwitch();
    }//GEN-LAST:event_port_forward_checkboxActionPerformed