Anchoring

Anchoring is one way to maintain position.

We should distinguish two different types of systems: permanent anchoring and retractable anchoring. Ships come equipped with a retractable anchoring system, but the accuracy of such a system is limited, as an anchor may drag across the ocean floor.

Permanent anchors/mooring systems are used for offshore platforms. They provide greater reliability than a typical retractible system. The standard way of setting a permanent anchor is by means of suction anchors.

The cost of anchoring is a function of depth, as the cables represent a significant part of the cost. And of course, the cost is a function of maximum force, which strongly correlates with total displacement.

Some data is available in [here], p3.

The setting is 6000ft water depth in the mexican gulf; the anchors are capable of withstanding hurricane force.

1M$ for a 1600st structure, and 4M$ for a 5500st structure.

These are material costs; installation costs are unclear, as they are lumped into another category. Including worst-case installation estimates, mooring costs are about 1/3 of total costs.

Assuming 50 people on a 5500st structure, the cost merely of getting a fixed location is large compared to what youd pay for land prices.