Blocks without a safe working load stamp must be subjected to what before use on ATON vessels?

• A. Repainted
• B. Photographed
• C. Inspected Daily
• D. Proof Tested

Answer: (D)

When a block lacks a safe working load stamp, you must verify its strength before putting it into service. This is done through proof testing, where a controlled, calibrated load is applied to the block well above what it would normally carry. The goal is to reveal any hidden defects or weaknesses by observing for deformation, cracking, or other signs of failure during the load application. If the block passes the test without damage, it can be certified for use and appropriately documented. If it fails, it must not be used.

Proof testing is essential on ATON vessels because rigging must reliably handle loads without risking personnel or navigational aids. Repainting, daily inspection, or photographing do not assess the actual load-bearing ability, so they are not substitutes for proof testing.