This changes the height field of an instrument object to 0,
so that it does not contribute to the overall length of the mooring.
Using this in deep water is unlikely to make much difference,
but it is handy for shallow-water cases, if the device was
clamped on to the wire, but the height field of the
instrument object used to represent it has non-zero height.
The example illustrates this, for mooring in very shallow water.
clamped(instrument)a mooring object of subtype instrument,
as created with instrument().
clamped returns a copy of its input, but with
the height value set to 0.
library(mooring)
# For clarity of the example, invent an anchor with no height,
# and a float with no height. Then compare the mooring height
# without clamping and with clamping.
a <- anchor("my anchor", buoyancy = -50, height = 0, CD = 0)
w <- function(length) wire(length = length)
i <- instrument("SBE37 microcat clamp-on style")
f <- float("my float", buoyancy = 20, height = 0, area = 0.2^2, CD = 1.3)
# Construct unclamped mooring (m) and clamped mooring (M).
m <- mooring(a, w(20), i, w(20), f, waterDepth = 50)
M <- mooring(a, w(20), clamped(i), w(20), f, waterDepth = 50)
# Compute the mooring lengths by summing the element heights.
# Notice that M is 40m long (the sum of the wire lengths)
# but that m is longer, because the instrument height is
# included.
sum(height(m))
#> [1] 40.559
sum(height(M))
#> [1] 40
height(i)
#> [1] 0.559