weather context

Onboard sensors can measure a number of weather variables, but there is a lot that they cannot. Waves for instance, are notoriously difficult to measure in situ, as well as some aspects of the wind, such as its vertical profile, or even the direction and speed of current of the water which are also missing from a lot of ship-based measurements. Hydroscope enriches your data with all the available meteorological data, generating up to 151 extra variables, to help explore the intricate ways in which the environment impacts your perfomance.

wind

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Because wind is what powers your ship, a lot of effort has been invested in characterising it as accurately as possible from a physical perspective, to manage to express all its complexity in as few numbers as possible.

air density

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The density of the air is an important factor when it comes to computing the amount of energy contained in the wind. Depending on the atmospheric conditions (air temperature, relative humidity and atmospheric pressure), there can be a few percent difference in the energy your sail receive for the same windspeed. It’s important to factor this when analysing a boat’s performance, as the more energy your sails receive the more propulsive force they generate.

wind gradient

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The way the windspeed changes with altitude (it’s profile) has a significant impact on the amount of energy your sail receive, especially in the case of tall masts. If the wind speed is constant with altitude or if it reaches the measured value progressively will change the average windspeed perceived by the sail, impacting its ability to provide thrust for the boat. This factor has to be taken into account for accurate performance prediction.

waves

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Waves have a critical impact on the performance of any yacht. Hydroscope adds all the relevant variables to your dataset, and uses a proven physical approach to factor this highly complex phenomenon in your performance analysis.

stokes drift

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Waves generate motion on any floating object they encounter. The speed at which ships are moved by waves is called ‘stokes drift velocity’, and although its computation can be fairly complex, it’s important to factor it in when analysing a ship’s performance as it can artificially increase or decrease the ship’s speed relative to the water.

$$ \vec{u}_{s t}=\int \mathrm{d} f \mathrm{~d} \theta \frac{2 g k}{\omega \tanh (2 k D)} \vec{k} F(f, \theta) $$

spectrums

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Hydroscope can collect and process ‘wave spectrum’ data from meteorological models and use it for finer analysis of a boat’s performance on a given segment. This is the most detailed wave analysis method which can help measure the amount of energy the boat exchanges with the waves, and help quantify the impact of this on boatspeed.

water

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To accurately characterise the environment a ship evolves in, Hydroscope adds variables representing the state of the water, which can impact the amount of energy the boat receives and looses from the environment.

water density

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The density of water varies a few tenths of a percent depending on water temperature, atmospheric pressure and salinity. Hydroscope adds all these variables and computes the water density¹, which in turn is proportional to the amount of drag and buoyancy of the yacht, directly impacting its performance as a result.

current

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Tidal, barotropic and thermohaline currents generate motion on the water a boat sails upon. This can significantly impact the wind, and therefore the energy a boat receives. That is why Hydroscope complements your data with the most accurate current models available, in order to factor this into your performance analysis.

environment

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Hydroscope combines all the relevant information regarding the external parameters of the yacht into an ’environment’ object. This allows several quantities which can impact performance to be computed by mixing different variables.

environmental wind

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Hydroscope computes the wind received by a boat at any given time as the difference between the true wind, and the ship motion generated by waves and current. This water referenced ’environmental wind’ is the wind that the boat actually feels, and should be used as a basis for analysing its performance.

miscellaneous

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Other variables can also be added to the dataset to reduce the performance prediction error even further. Hydroscope can track the position of the sun and moon relative to the yacht, the intensity of the earth’s gravitational pull, as well as the value of the ‘coriolis pseudo-force’ acting on the yacht, so that their impact on performance can be studied.