What issue often plagued early 19th-century metal anchors that drove the focus toward stockless designs?

Answer

The arms parting at the crown when being hauled from firm ground

Until metallurgy improved, anchors made of imperfect iron often failed structurally, causing the arms to break away at the crown point when the anchor was heavily stressed during retrieval from solid ground.

What issue often plagued early 19th-century metal anchors that drove the focus toward stockless designs?
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