Why oil rigs make vulnerable observation posts

Would repurposed oil rigs make useful maritime observation posts?

They could carry sensors, but their fixed location and wartime resupply burden would make them hard to protect.

Oil rigs can carry sensors, but their fixed position is a decisive weakness. They can move only slowly, making them predictable targets that are difficult to defend in a war zone. Their continuing resupply would create another exposed logistics task for the fleet. The sensor capacity does not compensate for the protection and sustainment burden.