The past form of the ott is the "onvoltooid verleden tijd" (ovt; past simple). How verbs are conjugated (changed) in the ovt is not easy to understand. Mistakes are common because some verbs are add a D, but others add a T. The "'t kofschip" rule is that the verb without "-en" (the stem in most verbs) ends with a consonant, which is also in "'t kofschip", the verb is changed with a T: