The Gaul would have completely lost her stability at an angle of heel of 26°

IMCO’s [1] ‘Recommendation on intact stability of fishing vessels’ states:

(10) In cases where the ship would sink due to flooding through any openings, the stability curve should be cut short at the corresponding angle of flooding and the ship should be considered to have entirely lost her stability.

The Gaul sank due to flooding started at the duff chute opening, when this became immersed at a heel angle of only 26º (see RFI final report Para. 17.5, page 245).

This angle of heel, at which the Gaul’s stability disappeared, was in breach of IMCO’s recommended criteria for the stability of fishing vessels which requires that a vessel should have sufficient stability at angles of heel beyond 30º.
----------------------------------------------------------------------------------[1] IMCO – Inter-Governmental Maritime Consultative Organization, now known as IMO