Half of the Navy’s littoral combat ship fleet is suffering from structural defects that have led to hull cracks on several vessels, limiting the speed and sea states in which some ships can operate, according to internal records obtained by Navy Times and confirmed by sea service officials.

The Navy has not previously disclosed the cracks in the Independence-class version of the LCS or the class-wide repercussions of the defects, nor has it identified which ships suffer from the issues.

But documents obtained by Navy Times warn that cracks can grow if the ships transits faster than 15 knots in seas with maximum wave heights of about eight feet.

The troubling revelations come as the Navy continues to grapple with a class-wide transmission issue in the Freedom-class variant of the LCS, and sea service leaders seek to decommission all of those ships, years ahead of the expected end of their service lives.