Off shore lifting equipment certificate?

Hope someone can please help. How does a lifting certificate for off shore differ from an on site insurance inspection certificate? I had a lifting company on site Today to carry out our 6 Monthly inspection on our lifting equipmnet (Slings, Eye-Bolts, Shackles Etc.) Prior to Today if i was ever shipping lifting gear off shore i would send a copy of the original certificate along with a copy of the 6 Monthly inspection certificate if the equipment had expired from the base certification date. But Today i was told the 6 Monthly inspection certificate was for use of the lifting gear On Site & On Site only if the equipment was being shipped off shore another inspection would have to be carried out & new certificate produced. Is this correct? how can the integrity of the lifting gear be deemed fit for purpose at my place of work yet need a diferent inspection, certificate for shipping to an oil platform.