The law related to performance claims is not easy, as many technical issues are involved. Whilst, at first, it may seem easy to claim that a vessel has under performed there are a wealth of factors which must be taken into consideration in order to do so. Often expert advice must be used in order to justify or defend such a claim. This can be a very expensive exercise. However, by recognizing the potential pitfalls and hazards a performance clause can be formulated and agreed by the owners and charterers which will remove much of the uncertainty from the subject and leave the potential for dispute at a minimum. As a postscript it may be helpful to consider the following dispute that arose some years ago. At the end of a time charter a number of issues were outstanding including a relatively modest performance claim.