Time Charterers relied on vessel underperformance and withheld final hire. Owners claimed that the deduction was not made in good faith or on reasonable grounds. The Tribunal dismissed Charterers' reliance on a weather routing report, and held Charterers had failed to address the question of good faith, to substantiate their off-hire claim, and to address Owners’ assertion there was no speed/consumption warranty (the fixture containing the words “all details about/in good faith”). Owners were entitled to payment.