dive {scuba}R Documentation

Define a Dive Profile

Description

Define a dive profile.

Usage

  dive(..., begin=0, end=0, tanklist=NULL)

Arguments

... Any number of arguments, specifying a sequence of events that make up the dive. The arguments may specify depths, time spent at each depth, ascent or descent rates, and gas switches. See Details.
begin, end The depths at the start and finish of the dive (normally zero indicating that the dive starts and finishes at the surface).
tanklist Optional list of the gases contained in each tank, for a dive with multiple tanks.

Details

This function creates an object of class "dive" which represents a scuba dive. The dive profile is assumed to be piecewise linear, that is, the graph of depth against time is a broken straight line. Dives are assumed to start and finish at the surface.

The arguments ... specify a succession of events that make up the dive. Each argument can be

a vector of length 2
interpreted as c(depth, duration) where depth gives the depth in metres and duration the length of stay at this depth, in minutes.
a single number
interpreted as a waypoint depth in metres. The diver will ascend or descend to this depth, at the current default rate of ascent or descent.
an object of class "gas"
specifying a breathing gas. Such objects are created by the functions nitrox and trimix. The diver switches to this gas.
an argument of the form tank=n
specifying a switch to another tank or cylinder of breathing gas. This is available only when the tanks used in the dive have been specified by the argument tanklist. The value n should be a valid index for this list (either a serial number in the tank list or a character string matching one of the names in the tank list).
an ascent/descent rate object
created by the functions ascent or descent. This resets the default rate of ascent or descent.
a data frame with 2 columns
containing a dive profile, usually uploaded from a dive computer. The first column should contain the elapsed times, and the second column contains the depths (in metres) measured at these times. The column of elapsed times can be either a character vector containing times in minutes-and-seconds format mm:ss, or an integer vector containing elapsed times in seconds, or a vector of class difftime representing elapsed times in any time unit.
an object of class "dive"
representing a dive profile. This allows the user to paste dive profiles together.

Dives are assumed to start and finish at the surface (this can be changed by specifying values for begin and end).

Initially the descent rate is set to 30 metres per minute, the descent rate is 18 metres per minute, and the breathing gas is air. These settings may be changed during the dive by the ... arguments.

A dive object may include periods spent at the surface (depth zero) and may therefore represent a succession of dives separated by surface intervals.

Once an object of class "dive" has been created, it can be plotted and printed (using plot.dive and print.dive). The nitrogen saturation can be computed using haldane and the cumulative oxygen toxicity using oxtox.

Value

An object of class "dive" describing the dive profile and the breathing gases used.

Modifying a dive object

The depths and elapsed times at each waypoint during the dive can be extracted and changed using depths.dive and times.dive.

It is possible to alter the breathing gases used in a dive d, yielding a new dive object. You simply modify the tanklist using tanklist(d) <- value. This makes it possible to study the effect of conducting the same dive profile with a different breathing gas.

Warnings

Not suitable for representing altitude dives.

Author(s)

Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/

See Also

nitrox, ascent, descent, haldane, plot.dive, times.dive, durations.dive, depths.dive, chop.dive, tanklist.

Examples

  # Dive to 25 m for 20 min followed by safety stop at 5 metres for 3 min
  d <- dive(c(25,20),c(5,3))
  plot(d)

  # Bounce dive to 20 metres
  d <- dive(20)

  # Two dives separated by a one-hour surface interval
  d <- dive(c(30,15),c(9,2),c(5,5),c(0,60),c(12,60),c(5,5))

  # ASCENT RATES
  # Ascent rate 18 m/min below 9 metres, 6m/min above 9 metres
  d <- dive(c(30, 12), ascent(18), 9, ascent(6), c(5,3))

  # UPLOADED DIVE PROFILE
  data(baron)
  pro <- baron[, 1:2]
  d <- dive(pro)
  plot(d)

  # GAS USE
  # 30-metre dive on Nitrox 32
  d <- dive(nitrox(0.32), c(30,20), c(5,5))

  # GAS SWITCHING
  # Dive to 18 m for 30 min on air,
  # switch to Nitrox 36, ascend to 5 metres, safety stop
  d <- dive(c(18, 30), nitrox(0.36), c(5,3))
  # Same as above, but ascend to 5 m on air, then switch gas
  d <- dive(c(18, 30), 5, nitrox(0.36), c(5,3))

  # SWITCHING TO SPECIFIC TANKS
  d <- dive(tanklist=list(main=air, deco=nitrox(0.50)),
            tank="main", c(30, 20), 5, tank="deco", c(5,10))

  # Descend to 5 metres on pure oxygen, switch to Trimix,
  # descend to 30 metres, remain 40 minutes, ascend to 6 metres,
  # switch to pure oxygen, ascend to 5 metres, decompress 10 minutes,
  # surface and continue breathing pure oxygen for 10 minutes

  d <- dive(tanklist=list(travel=trimix(0.15, 0.5), deco=nitrox(1)),
            tank="deco", 5, tank="travel", c(30,40), 6, tank="deco",
            c(5,10), c(0,10))


[Package scuba version 1.2-2 Index]