Create an anchor object

Create a anchor object, either by looking up a known object from the database, or by defining a new type. This must be the first element of a mooring constructed with mooring().

anchor(model = "1 Railway Wheel", buoyancy = NULL, height = NULL, CD = NULL)

Arguments

model

character value indicating the type of anchor. There are three possibilities for model. (1) If this is "?", then the function returns a vector of permitted character values. (2) If this is "?X", where X is a set of characters, then findElement() is called to do a fuzzy search, with the search argument set to "anchor". (3) If it is recognized, i.e. if that type is stored in data(mooringElements), then the that stored value is used, and all other arguments to this function are ignored. (4) Otherwise, a new anchor object is created, using values specified in the other arguments (all of which must be supplied).

buoyancy

numeric value indicating buoyancy. For wire elements, this is buoyancy per length, expressed in kg/m. For other elements, it is buoyancy, expressed in kg. Note that buoyancy is ignored if model is recognized.

height

numeric value for the height (in m) of the element. This value is used in the computation of the mooring geometry. In some cases, as e.g. in Dewey-derived data that have "diameter" tabulated as zero, it is also used in the computation of the area of the element, as height*width. Note that height is ignored if model is recognized.

CD

numeric value (unitless) for the drag coefficient. Note that CD is ignored if model is recognized.

Value

anchor returns a "mooringElement" object with "anchor" subclass.

See also

Other functions that create mooring elements: chain(), connector(), float(), instrument(), misc(), release(), wire()

Author

Dan Kelley

Examples

library(mooring)
# List known anchor types
anchor("?")
#>  [1] "1 Concrete Block"      "1 Large St/C Tire"     "1 Railway Wheel"      
#>  [4] "1 Tire-St+Con"         "1 rotor"               "10 rotor"             
#>  [7] "2 Concrete Blocks"     "2 Railway Wheels"      "2 rotor"              
#> [10] "3 Concrete Blocks"     "3 Railway Wheels"      "3 rotor"              
#> [13] "3 trainwheels"         "4 Railway Wheels"      "4 rotor"              
#> [16] "5 rotor"               "6 rotor"               "7 rotor"              
#> [19] "8 rotor"               "8x8x16 cinder block"   "8x8x16 concrete block"
#> [22] "9 rotor"