Lead Scuba Diving app for iPhone and iPad

What

Lead is a mobile application that allows to evaluate the amount of weight required for every dive. Lead implements two methods of evaluation, Archimedes and PADIs Basic Weighting Guidelines.

Archimedes method

With this method, Lead evaluates the amount of weight to carry by applying the archimedes principle on the diver body, set of gears in a specific environment. Each element is considered as a mass and volume to compute the resulting buoyancy.

Basic Weighting Guidelines method

With this method, Lead evaluates the amount of weight to carry by following the PADIs basic weighting guidelines. The result is meant to be a starting point for a buoyancy check.


Why

The amount of weight required for a dive is important to maintain a good buoyancy. Divers are advised to follow basic weight guidelines in order to get an estimation about the amount of weight to carry and fine tune this amount through experience in each environment. Ultimately, divers should reach the perfect weighting for a given environment and keep track of it in a log book for further reference.

When diving in new conditions, divers should refer to basic weight guidelines again and start the fine tuning process.

Lead aims at leveraging the divers built up experience and automatically evaluate the equivalent amount of weight in different conditions.

How

Archimedes method

Lead evaluates the minimum amount of weight required so that the scuba diver never ends up being positively buoyant during a dive with an empty BCD and lungs half full. This allows the scuba diver to control his ascent at any time.
The minimum amount of weight is related to the maximum buoyancy which is computed using the Archimedes principle.
The density of the water is computed via a seawater model.

Default values for water temprature and salinity are obtained from NASA Open Data based on geolocation and date.

The human body volume and density is computed via a two-compartment model incorporating the person gender, age, height and weight. The volume is computed for a subject holding a normal breath in his lungs.

The volume maximum and mass minimum for gears is taken or derived from data sheets.
The volume for wet suits is approximated depending on the scuba diver body surface and the wet suit thickness.

Basic Weighting Guidelines method

The PADIs Basic Weighting Guidelines is implemented and takes into account the buoyancy of the cylinders, the type of suits, the diver fitness (computed through a model).


Features

* Evaluates the minium amount of lead to carry for a dive
* Archimedes method
* PADIs Basic Weighting Guidelines method
* Detailed computation results
* Metric/Imperial units
* Hydrostatic characteristics of typical gears
* Evaluation of Seawater density out of a model including salinity and temperature
* Default seawater salinity and temperature derived from based on geolocation (selectable) and date (selectable)
* Works offline (except map)

Lead is also available as a web app at http://wildbits.github.io
Lead is open source at https://github.com/wildbits/lead suggestions are welcome