The chronicle of an adventure

作者：Penny Boviatsou

On October 19, 2014 Matteo Miceli, a famous Italian oceanic sailor, left the Port of Riva di Traiano located close to Rome, Italy, with the Italian sailboat ECO40 for the Roma Ocean World Project. His goal was to sail around the world alone, without the help of any fossil fuel or additional supplies, other than what he brought with him for the entire 27,000 nautical miles (50,000 kilometres) journey.

ECO40类40海洋船(总长度of 12,0 metres) that was equipped with a data acquisition system for both the met-ocean parameters recorded on-board (i.e. apparent and real wind speed and wind direction, atmospheric pressure, current velocity, air and sea temperature, etc.) and the kinematic characteristics of the boat itself (i.e. speed and course over ground). A team of professors from the University of Rome and the Polytechnic Turin recorded the boat’s movements by using three Leica GR25 GNSS reference receivers. With these they were able to:

• Calculate the height of waves along the ECO40 route by using the boat as a buoy and validate the numerical models of the United Kingdom - based Met (meteorology) office;
• Improve the structural design of the Class 40 sailboat by means of calculating the boat’s dynamic stress and boat material durability during the trip;
• 记录从Eco40的动作中获取的波浪特性，以产生船速度的极图，这对于将来的40级赛车船非常有用。

Miceli transmitted the data via satellite for analysing to Professors Paolo De Girolamo and Mattia Crespi of the University of Roma La Sapienza and to Alessandro Pezzoli of the Polytechnic Turin.

On his way back to Italy, after rounding the three capes and sailing for 25,000 nautical miles, the ECO40 capsized at the Equator. Matteo was about 600 miles offshore the Brazilian coasts. He was saved by a cargo ship. When he came back to Italy, he organised a first expedition to try to recover ECO40, which was not successful. After a month, the expedition team tried again and found ECO40 300 miles offshore the Brazilian coasts. Now the vessel is back in Italy.

Fortunately, the data were saved together with the boat and the researchers were able to do the final analysis of the journey.

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The sailor’s journey

计划中的路线是经典的快船路线，它利用强烈的西风从西到东穿过南海。即，这条路线是通过直布罗陀海峡的组成，然后沿着大西洋下降并在南极绕着南极，平均纬度为50°S，从西部到东，绕过世界上最著名的斗篷：好希望斗篷，开普，开普，开普，开普Leeuwin和Cape Horn。最后，将大西洋航行回到直布罗陀海峡，然后回到主港。

“The data collected by the Leica GR25 GNSS receiver and the Leica AS10 antenna concerning the movement of the boat reported that ECO40 sailed wave heights of roughly 6 metres during the first storm with maximum waves reaching 10,0 m,” said Miceli. “After the end of the trip, we are now able to calculate the exact measurements.”

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Gathering the data

m的一部分easured data was sent to the land team on daily basis by satellite modem. These data, measured by the boat and transmitted almost in real time, helped significantly the team in charge of the safety of ECO40; the knowledge of the actual weather conditions the boat was really facing during the navigation could improve the route strategy and increase the boat safety.

Miceli说：“如果正确分析，从三个GPS接收器获得的船只移动的测量可以提供衡量ECO40在导航期间遇到的波浪的量度。”

The three high precision Leica Geosystems GPS receivers were placed on the left and right side of the stern along the boat cross axis while the remaining one was placed close to the boat entrance along the boat’s main longitudinal axis. The data were acquired by the system during the navigation of the ECO40 and stored on a flash-card by each receiver. The data analysis was carried out in post-processing after the recovery of the flash-cards.

Two different strategies were adopted in the post-processing:

1. The “Variometric Approach for Displacements Analysis Standalone Engine” (VADASE)
2. The moving base kinematic approach.

The two methods were used complementary in order to obtain the boat motion, and the boat motion has been applied to estimate the waves’ properties faced by the sailboat during its navigation around the world.

Indeed, the first (i.e. variometric approach) was used to calculate the boat heave, surge and sway motions, while the second one (i.e. moving base kinematic approach) was used to calculate the roll, pitch and yaw motions. The wave characteristics (i.e. directional wave spectrum) were derived by using the heave, pitch and roll motions.

When fast movements have to be detected and their effects suddenly evaluated, Leica VADASE can help researchers make the most informed decisions immediately. The solution adds additional value to traditional GNSS monitoring, providing accurate velocity information based on a stand-alone GNSS receiver that is continually available in real time for precise and reliable analysis of fast movements.

The boat performance data (i.e. speed and course over ground) can allow, after a certain amount of time that is required, to obtain a statistically meaningful database, to estimate the real polar velocity curves of the boat. Indeed these curves were used for the prediction of the optimal route made by the land team by using a route optimisation software, which was sent daily to Miceli.

The actual polar velocity curves of the boat differ from the theoretical ones estimated by the designer of the boat. This is due to several causes, among which plays an important role the ability of the crew to “push” the boat to the maximum of its performance and the presence of waves that normally is not taken into account when calculating the curves themselves.

These data are used mainly for two technical and scientific purposes:

1. The first purpose is the calibration and/ or verification of the numerical models output that are commonly used for the wind and wave forecast and/or analysis into the oceans, and the calibration of the remote sensing data (e.g. satellite wind and wave measurements).
2. The second purpose is directly related to the vessel design. Indeed the knowledge of both the movements and the loads that this kind of vessel can deal with, together with the response of the materials to the fatigue stresses, can improve significantly the design methods.

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Analysing the measurements

This undertaking was the first time ever that a sailboat’s movement was accurately measured by GNSS on a global journey and data were transmitted via satellite every few hours. In terms of the met-ocean conditions and in terms of the boat heeling, the first violent storm experienced by the ECO40 during its navigation occurred in the Gulf of Lion 21-22 October 2014. The heeling of the boat was estimated by using the GPS signals that were analysed by using a moving base kinematic approach. This analysis allowed to estimate the heeling angle α during the whole storm event.

“Concerning the met-ocean conditions, we analysed the storm on the basis of the wind data that were measured and transmitted almost in real time from the boat,” said De Girolamo.

通过放置在桅杆顶部的风速计，在ECO40的板上测量了风数据。第一次比较与欧洲中范围的天气预报中心（ECMWF）进行，第二个比较是通过使用数值模型GFS（全局预测系统）提供的预测数据进行的。

This comparison, along with the results of the heeling analysis, showed that the wind measurement height plays an important role. The corrected measurements of the wind are comparable with the results obtained from the numerical models: a good agreement is noticeable within the first 60 hours. Nevertheless, a sensible discrepancy between the measured wind data and the numerical one is noticeable as the storm peak occurs.

预测，预测，预测和测得的风速之间的直接比较显示了相关差异。这些差异是因为在严重的风暴条件下，预测风条件的预测状况为50％。

The researchers and professors were able to put together a research paper based on the comparison between measured and numerical wind data.

“Still, despite the unexpected end of the journey, the data collected from the Leica GR25 GNSS receiver and the Leica AS10 antenna were enough to provide ocean scientific information for the development of new ocean knowledge and technologies for the benefit of society,” said Frank Pache Senior Product Manager, GNSS Networks and Reference Stations at Leica Geosystems.