A boat tie-down strap is likely to become loose when transporting a boat if the boat straps are not at least 12" away from any other strap. This means that all models should be used in pairs, with two sets of side support on either side of the boat and one set of rear-end support for additional security.
If you find your transom tie-downs coming undone during transport or use, then they may need replacing soon - inspect them after every few uses!
Tip: These products should be inspected after a few uses and replaced when they show signs of wear or fraying.