An apparatus comprises a vessel, a first vertical support, a second vertical support, and a series of insulating panels. The first vertical support and the second vertical support are fixated to the vessel such that the first vertical support is spaced apart from the second vertical support. Each of the insulating panels in the series of insulating panels is supported between the first vertical support and the second vertical support. Moreover, each insulating panel in the series of insulating panels slidably overlaps one or more adjacent insulating panels in the series of insulating panels.