4） if any specified materials are not available when required for incorporation on the yacht， the builder shall be at liberty to use other suitable materials in substitution therefore， subject to the approval of the buyer， which approval shall not be unreasonably withheld. any adjustment to the contract， delivery date or design specification resulting from such substitution shall be made in accordance with the provisions of article iv.
5） during construction of the yacht， the builder will permit the buyer‘s representative to attend the tests specified in article viii and to have access to the boatyard during ordinary working hours while work is proceeding on the yacht. the builder must give reasonable notice of such tests to the buyer’s representative in writing. the builder will use its reasonable endeavours to arrange for the buyer‘s representative to have access to the premises of the builder's subcontractors for the purpose of inspecting materials and workmanship. if， during construction， the buyer or his representative alleges any defect or omission in the yacht they shall， if required by the builder， immediately specify the same in writing. if the builder agrees that there has been a defect the builder will at its own cost， before delivery， rectify the same.
6） the build will be subject to regular inspections by the buyer. accommodation， meals and entertainment in china for the buyer‘s staff that are paid for by the builder， will be invoiced to the buyer at cost. the buyer will cover his own travel costs to and from the boatyard.
7） the builder undertakes to provide a suitably qualified （english speaking） marine engineer to act as a liaison person with the buyer throughout the duration of this contract.
8） where practical the builder shall take and make available to the buyer， digital photographic evidence of all construction， painting and fit out stages during the yacht‘s build. such digital information will be sent to the buyer or the buyer’s representative by electronic means and at such frequency to allow the buyer or the buyer‘s representative to monitor the course of the yacht’s build.
9） the materials， components and equipment for the yacht （as detailed and agreed on the component supply list in annex a） that are the builder‘s supply will be shipped to the boatyard by the builder at his expense. shipping costs of items of buyer’s supply will be at the buyer‘s cost together with associated export and import procedures， duties and insurance.