Since cost estimates are often required well in advance of
the contract design phase, the US Navy developed a method
which is based on a single common parameter: weight. The
basic construction cost of a ship is then directly
determined, through the use of historically determined
factors. These form cost estimating relationships (CER's)
that are used to provide parametric analysis of ship
construction costs. This method uses the Ship Work
Breakdown Structure (SWBS) as a common means of
communicating the level of technical definition between the
designer, shipyard and cost estimator.