Exclusive ECONOMIC Zone - 200 nautical miles out from shore
The Exclusion Zone being talked about wrt the offshore installation is a zone extending 3,000 metres out from the installation or field if the field is in production and there are a number of installations making up that operating offshore oil field
The Safety Zone round a Platform extends 500 metres out from that particular installation - the safety they are primarily referring to is the safety of the installation itself or of existing installed subsea infrastructure. As supplies and equipment are loaded and unloaded in this zone specific areas are designated for these crane operations and all seabed infrastructure within the 500 metre Safety Zone is designed to withstand and is protected against snagging and dropped objects. Inside the 500 metre zone the OIM of the installation is legally responsible for the safety of all equipment and personnel, that is why it requires his say so to enter - now a bunch of clowns bouncing about in inflatable craft who have got no right or authorisation to be there, hell bent on doing God knows what most certainly would constitute a safety hazard in my eyes if I were the OIM.