The most important exceptions from hull cover in Chapter 12 are the exceptions in Clauses 12-3 (inadequate maintenance, etc.), and 12-4 (error in design of parts not approved by the class). These exceptions will not be dealt with here, other than to note that loss of time during repairs of damage to the hull and/or machinery due to lack of maintenance etc. is not recoverable under the loss of hire insurance. For a detailed discussion of these exceptions, see the Commentary to Cl. 12-3 to Cl. 12-5 and Brækhus and Rein: Kaskoboken, pages 86-108, on the similar, but not identical provisions of the 1964 Plan, Clauses 175 and 176 (m), and Wilhelmsen and Bull, Handbook in Hull Insurance, chapter 10.5.