This assertion is only partly valid. Cracks in A-brackets or spectacle frames (the shaft brackets supporting the propeller shaft) are more commonly the result of fatigue due to fluctuating loads, stress concentrations at the bracket-to-hull connection, and the vibration and whipping of the shaft, rather than simply inadequate scantlings. The brackets are subject to severe alternating loads from the propeller and the shaft, and cracks typically initiate at stress raisers (sharp corners, weld toes, the bracket arm-to-hull connection) and propagate under fatigue. While inadequate scantlings or poor design (insufficient section, poor connection, sharp notches) can contribute, the primary cause is usually fatigue and stress concentration, aggravated by vibration, corrosion and the dynamic loads of the propeller. Hence the assertion is not fully valid: crack propagation is more indicative of fatigue and stress concentration than of inadequate strength alone, and the design should address the fatigue life, the connection detail and the avoidance of stress raisers, as well as the scantlings.

This assertion is largely valid. Freeing ports (openings in the bulwark that allow water shipped on deck to drain overboard) are essential to seaworthiness because, if they are inadequate, water accumulating on the deck cannot drain, which:

• increases the free-surface effect and the weight of water on deck, reducing stability and increasing the risk of capsize;
• increases the deck load and the risk of structural damage;
• reduces the reserve buoyancy and can lead to the ship becoming unstable.

Watertight integrity (the ability of the hull and its openings to keep water out) is equally critical to seaworthiness, as it prevents flooding and loss of buoyancy. Both are essential: watertight integrity keeps water out, while freeing ports remove water that is shipped on deck. If either is inadequate, the ship's seaworthiness is compromised. Hence the assertion is valid - freeing ports are as critical to seaworthiness as watertight integrity, because they maintain the stability and buoyancy of the ship by removing deck water.