901

1 INTRODUCTION

This paper is an analysis of the possibilities of using a

Raspberry Pi microcomputer on board a ship. The

main purpose of this paper is to find the possibility of

using this device to displace current traditional

measuring devices. The measurement data are to be

as close as possible to the values obtained by such

devices. The goal is also the development of ship

technology and finding a solution that allows it to be

used in all possible situations, such as power failures.

[1]

The first part of the work presents an analysis of

the use of computer systems on operational ships,

attention will be paid to the use of traditional

measuring devices in the aspect of meteorological

measurements. Measuring devices and their

operating ranges will be presented. An aspect of the

use of this data by officers and mechanics during the

operation of merchant ships will be presented.

The next part will present the Raspberry Pi

microcomputer, its technical data and operating

systems on which the device works. In addition, the

Python programming language will be presented.

This language will be needed to create a code that

will read data from meteorological station sensors

and display ready values of temperatures,

atmospheric pressure and humidity.

The last part of the work is a project to build a

meteorological station on a merchant ship. First, the

sensors used, their dimensions and methods of

connecting to the microcomputer will be presented.

Then, by using ready-made scripts for individual

sensors, the first measurements will be presented.

Scripts should be programmed to display both sensor

values simultaneously. The values will be presented

by calling the code to minimize the use of

microcomputer resourses.

The Single-board Computer As a Toll to Measure the

Weather Parameters in the Marine Areas

T. Neumann

Gdynia Maritime University, Gdynia, Poland

ABSTRACT: This paper is an analysis of the possibilities of using a Raspberry Pi microcomputer on a ship. The

paper is an introduction characterizing the project goal and its main assumptions. It includes a brief history of

shipping development and the current use of computer systems on board merchant ships. Also meteorological

devices have been characterized that can be used on the ship to obtain weather data. The paper also includes

description of the Raspberry Pi microcomputer, its specification and operating systems on which the device

works. The project of a station is designed to measure the value of air and water temperature, humidity and

atmospheric pressure.

http://www.transnav.eu

the International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 14

Number 4

December 2020

DOI: 10.12716/1001.14.04.14

902

2 METEOROLOGY AT SEA

Meteorology is the science that deals with the study

of physical phenomena and processes occurring in

the atmosphere, in particular in its lowest layer - the

troposphere. These processes affect how the weather

and climate in a given area are shaped.

Meteorological conditions play an important role in

maritime transport, where not only sailing time

matters, but also the safety of crew and ship. The

officer must take into account factors such as the state

of the sea, visibility, tide level, temperature, currents

and even the presence of ice cream in a given area,

both when planning the ship's route and conducting

the watch. Constant observation of these factors on

the bridge is therefore crucial if we want to carry out

a ship from one port to another without problems,

especially if the journey is counted in weeks. [2]

The main source of valuable information about the

weather on the ship are primarily visual observations

conducted by an officer or a watchman. Skillful

assessment of the state of the sea, wave height and

visibility allows a sufficient level to determine the

prevailing weather and often how it will shape over

the next few hours.

A hygrometer, i.e. an instrument constructed of a

dry and wet thermometer, is increasingly used to

measure the temperature on a ship. This instrument

is often placed on both wings of the sternum. Based

on the temperature differences indicated by both

thermometers, we can read the value of relative

humidity from special tables or psychometric charts.

In order to determine the wind speed and its

direction, a sailor may suggest the state of the sea and

its surface, in addition most ships are equipped with

a device called an anemometer, which measures the

speed of air, gas and liquid flow. The most common

solution is a portable anemometer, although wind

gauges are being installed more and more often on

ships, sending information about wind speed and

direction remotely to devices on the bridge.

The device for measuring atmospheric pressure is

a barometer. Depending on the principle of

operation, we distinguish a liquid and spring

barometer, the so-called aneroid, which is most often

placed on the ship's bridge. Rapid changes in

pressure often correlate with occurring weather

changes. Low pressure is often associated with

adverse weather phenomena such as typhoons and

hurricanes. High, in turn, is usually high-

temperature, sunny weather. At sea level, the average

atmospheric pressure is 1013 hPa. [3]

Observation of the cloud cover is not the most

difficult tasks when the sky is clear or completely

covered with clouds. However, the ability to identify

clouds in the sky is useful when it is partly cloudy.

Knowing the characteristics of the precipitation of a

given cloud, we are able to determine whether, for

example, planned painting work on board can be

interrupted by the coming rain and make the right

decision. [4,5]

3 USE OF IT SYSTEMS ON THE SHIP

The history of merchant ships goes back to ancient

centuries. Ancient Greeks and Romans aboard their

ships carried out trade expeditions throughout the

Mediterranean, as well as nearby waters accessible to

their ships. They were built of wood, and used their

sails or the strength of human muscles for their

motive power. The operation of ships consisted

mainly of sailing with a given commodity to a

specific port where it was sold and new buyers were

gained. Navigation was mainly based on sailing on

known seas and routes. There were no maps, so the

position of the ship could not be determined. Over

the years, the appearance, characteristics and

capabilities of ships have changed. Crossing oceans

and discovering the world began. Discoverers such as

Christopher Columbus and Ferdinand Magellan have

reached new previously unknown lands. In 1110,

magnetic compasses appeared, which began to

determine directions, and one hundred and sixty

years later in 1270, the first maps appeared. [6] At the

end of the nineteenth century, units made of concrete

and then of steel began to arise. The first units

received steam engines, and transatlantic journeys

became commonplace. However, it has only been in

the last few decades that ships have received

something that officers and mechanics owe to easier,

safer and more effective work. They are computing,

monitoring and alarming systems based on computer

networks.[7]

Such networks allow a deeper understanding of

the processes occurring in individual devices. On the

hull, in ballast and fuel tanks, in the main engine and

many other locations there are sensors constantly

monitoring parameters, which are transmitted to the

main unit, which thanks to computer systems

connected to the ship's network transmits current

data.

4 RASPBERRY PI – MICROCOMPUTER’S

SPECIFICATION

Technological progress has developed significantly

over the last several years. The equipment available

on the market now, compared to that of the early 90s

of the last century, is huge. Not only in terms of

materials and the availability of such devices, but

primarily due to the computational capabilities and

their sizes. The first computer created during the war

called ENIAC (Electronic Numerical Integrator And

Computer) had an area of 140 square meters, i.e. a

medium-sized single-family house. His

computational abilities allowed for basic calculations

related to military subjects. The computer was mainly

used for ballistic and nuclear weapons calculations.

[8]

Over time, computers have become smaller and

more accessible to ordinary users. Home and

personal computers were created, followed by

notebooks. However, a very important date in the

history of personal computers was February 29, 2012.

That day, the smallest computer, the Raspberry Pi

microcomputer, went on sale (see Fig. 1). It was

903

the University of Cambridge. Its main chairman is

Eden Upton, who is still trying to improve this

microcomputer so that he can accommodate the most

efficient components in its small dimensions. [9]

Figure 1. Raspberry Pi 3 B

The technical specification of the device based on

materials obtained from the microcomputer manual

and the website of the Polish distributor will be

presented below. The presented model is one of the

basic manufacturer, and the data may vary

depending on the version selected.

Table 1. Specifications of Raspberry Pi 3 B device

_______________________________________________

Raspberry Pi 3 model B

Processor Broadcom BCM2837 64-bit

Core Quad-Core ARM Cortex A53

Operating system Linux Raspbian

CPU clock speed 1,2 GHz

Architecture ARMv8-A

RAM 1GB LPDDR2 @ 900 MHz

Memory microSD card

GPIO Socket Connector 40-pin (2x20) raster 2,54mm

Power 5 V / 2 A microUSB input

Dimensions 85x56x17 mm

USB interface 4x USB2.0 gniazdo typ A

Network interface Port Ethernet 10/100 Mbps

WiFi interface 802.11 b/g/n 150 Mbps

Bluetooth BLE 4.1

_______________________________________________

As you can see in the table above, despite the

small dimensions, the components contained in the

device allowed to create a microcomputer with very

interesting parameters. It is worth adding that the

computer has an additional WiFi and Bluetooth

interface.

Figure 2. Outputs and inputs in Raspberry Pi 3 B

Inputs and outputs available on the Raspberry Pi 3

B microcomputer (see Fig. 2): [10]

− A. USB port - 4 USB 2.0 ports allowing you to

connect external entities such as an external disk,

pendrive, ROM etc. However, due to the low

power consumption, by the microcomputer itself,

USB sockets offer lower power than standard

sockets in personal computers

− B. Ethernet port - standard input for local

networks, so-called cable connection with RJ45

plug. It allows you to connect the microcomputer

to a wider computer network.

− C. Video Composite RCA output - analog video

signal output. The signal is sent in NTSC or PAL

formats. The quality of the transmitted image is a

maximum of 480i or SD (Standard-Definition).

− D. HDMI output - interface for sending video and

audio in a digital form. The sent image can be in

UHD (Ultra High Definition) format, i.e. 4K. It can

be used when using a microcomputer as, among

others multimedia platform.

− E. Power socket - microUSB input, identical to

mobile phones, 5 V / 2 A.

− F. DSI 15-pin socket - the last available video

output on the board, commonly used for

connecting LCD monitors.

− G. GPIO port - 40 pins for connecting peripheral

devices to the microcomputer. They can be both

input and output devices.

There is also one slot on the other side of the main

board under the DSI socket (see point F) and is used

to support microSD cards. This is an important socket

due to the characteristics of the device, which, having

a very small internal memory, does not have an

operating system installed. Therefore, it is important

for the device to have a microSD card with the

operating system installed before it is turned on. It

will also allow you to operate easily between

different operating systems, only by changing the

microSD card.

Due to the use of GPIO sockets in the rest of the

work, it is important to provide their specifications

(see Fig. 3).

Figure 3. Specification of GPIO sockets

Due to the adaptation of the device primarily to

programming, the operating system, which used in

the microcomputer must allow it to delve into its

source code. Unfortunately, the most popular

Windows or macOS available on the market are

closed-source systems. This means that it is kept

secret and no one except the creators knows what is

inside it. Free and open source is the English term for

free systems that provide users with the ability to

view and modify such code. [11]

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5 USE OF RASPBERRY PI

In the previous chapter, the Raspberry Pi

microcomputer was presented, which was used to

create a weather station that is the goal of this thesis.

The weather station aims to measure basic weather

parameters that are needed to control the weather

situation and create entries in the ship's logbook. The

values are to be presented on one screen, refreshing

the displayed values every minute. This will allow

you to collect current information. [12]

Parameters presented by the weather station:

− Air temperature

− Water temperature

− Atmospheric pressure

− Air humidity

Wind strength and direction will not be

represented by the weather station. These parameters

are needed for safe navigation, their value must be

very accurate, and also be presented on several

devices at the same time. In addition, wind gusts

should be presented on an ongoing basis, which is

difficult to present based on basic sensors available to

a wide range of users, and additionally available for

connection to a microcomputer. It would also be

necessary to connect a gyro-compass / magnetic

compass and a log to determine the actual wind from

the apparent wind value represented by the

anemometer. The weather station I created is

designed to present weather information on one

small screen located at the table with the ship's

logbook. [13]

The station was created by connecting to a

Raspberry Pi microcomputer by more specifically to

GPIO sockets BME280 and DS18B20 sensors. The first

is a sensor for air temperature, atmospheric pressure

and humidity. The second is a waterproof probe for

measuring water temperature. The specifications of

both sensors are provided in the table below.

Table 2. Specification of weather station sensors

_______________________________________________

Parameter BME280 DS18B20

Interface SPI/ I2C 1 – wire (GPIO)

Temperature range - 40C - 85C -55C - 125C

Pressure range 300 hPa - 1100 hPa ---

Humidity range 0%RH - 100%RH ---

Temperature accuracy +/- 1℃ +/- 0,5℃

Pressure accuracy +/- 1 hPa --

Humidity accuracy +/- 3%RH --

Power 3,3V 3,0V

Dimensions 27 x 20 mm 6 x 51 mm

Cable length: 1 m

_______________________________________________

As you can see in the table above, these sensors

are very small in size, which allows them to be

installed anywhere outside the ship, as well as their

voltage consumption allows you to connect them and

the microcomputer to a standard power outlet. The

sensor ranges are very wide and sufficient for secure

weather forecasting. Regarding accuracy, the values

presented by the DS18B20 are small and the

maximum discrepancy is +/- 0.5 ℃. The BME280

sensor is a little less accurate, but they still show

sufficient values for the weather station being built.

Both sensors are basic devices widely available on the

market, therefore their accuracy difference is not

minimal. If the idea was used in maritime economy,

the sensors could become very accurate, additionally

supervised by meteorological institutions.

The first sensor to be connected is BME280. It

operates on the I2C interface, so it is important to

properly connect the wires from the sensor to the

GPIO sockets in the microcomputer. The photo below

shows how to connect the sensor to the

microcomputer.

Figure 4. BME280 sensor connected to the microcomputer

After connecting the sensor to the microcomputer,

the next step was to connect the Raspberry Pi to the

power supply and the screen on which the

measurement results could be displayed. Connecting

the sensor itself will not display the measurement

results on the screen, which is why a ready-made

script prepared by the creator of the Waveshare

BME280 sensor was used. The code fragment is

presented below, it is forcing the presentation of

temperature, pressure and humidity values.

Figure 5. Used Python Code Fragments

The code is assumed to display values on one line

with a refresh period of microseconds. It is quite

frequent to receive measurement results, but the user

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can control the functioning of the sensor, thanks to

which we can check whether the impact of external

objects can affect the result. For example, placing a

heat source on the sensor should increase the

temperature or placing the sensor near a water source

will change the humidity value.

Figure 6. BME280 sensor measurement ready

The next step was connecting the second sensor,

i.e. the DS18B20 probe, thanks to which the water

temperature values were obtained. A contact plate

was needed to connect the sensor to the

microcomputer (as in Fig. 7). The probe, unlike the

BME280 sensor, uses a GPIO interface, thanks to

which we can connect both sensors to the device at

the same time.

Figure 7. DS18B20 sensor connected to the contact plate

The code had to be programmed to get the results

of the water temperature measurement. Here, simple

code based on the previously presented Python

programming language was used. It is much simpler

than the sensor presented earlier, but the obtained

result is displayed only once after entering the

command.

Figure 8. Code for DS18B20 sensor

Therefore, it is necessary to develop and combine

both scripts to create one unified code, thanks to

which all measurements can be displayed on one

screen. In addition, the values displayed by both

sensors should be named accordingly, which is why

in the next stage I used the following words for the

parameters:

− Air temperature - air temperature

− Sea temperature - water temperature

− Pressure - atmospheric pressure

− Relative humidity

The values presented by the sensors on the final

display will be rounded to one decimal place and

will be displayed after calling the commands. The

values displayed continuously by the BME280 sensor

will slow down the microcomputer's operation by

limiting its RAM memory for a longer time. If the

sensors are to provide data to the microcomputer, it

is important that they are current and shown

immediately after calling the command under the

button on the display. Any slowdown or stopping the

system can cause imaging of unreal measurement

results. It is therefore important to create a code and a

way to visualize the results so simple that it does not

affect the negative operation of the microcomputer.

The first part necessary to create the report is to

determine how the code reads the data from the

sensor. In the BME280 manual you can find the code

snippet responsible for this task. The code loading

such data based on the sensor instruction was used.

Data are taken from the sensor address in the system.

6 PROPOSED DESIGN IMPROVEMENT AND

OTHER POSSIBLE USES OF THE RASPBERRY PI

MICROCOMPUTER

The project has many options for improvement. One

option is to create a barograph on the microcomputer

display. It could be based on creating a small

database with weather data. The system would

download the data in the background and save it to

the database at a 15-minute interval. The data would

operate in the database for 24 hours and then be

deleted to minimize the size of the database. The

system would use the collected data to create an

atmospheric pressure graph over a three-, six- and

twelve-hour range. The electronic barometer

indicated above has a similar application, however,

assuming this thesis, all sensors and meteorological

data will be displayed on one screen, therefore it

would be necessary to develop such a database and

create a program displaying the graph. [13]

In addition to the meteorological station, the

microcomputer could be found on a ship in many

906

other solutions. The first is to create a training station

for officers and crew. XBMC software could do this.

A computer connected to a monitor or TV would

play training materials during weekly / monthly

exercise alerts that are mandatory in accordance with

SOLAS convention and flag State regulations.

Raspberry Pi could also be used to create a

navigation station for lifeboats. Its small size, low

power consumption and the ability to connect a USB

device to it allows you to create a geographical

position display of the ship. For construction it

would be necessary to use a small LCD display and a

GPS receiver connected via a USB port (see Fig. 9.).

This solution would allow the unit's position to be

determined and to navigate safely to the mainland.

Figure 9. GPS receiver with USB plug

Another possibility of using such a

microcomputer is to create from it a spare computer

with a library of materials, instructions, procedures

and important ship documents, which could be used

during emergency situations, such as power loss. As

it was presented earlier, the power consumption of

this device is minimal, so that the batteries available

on the ship could last much longer than when

operating on desktop computers. In addition, its size

and the ability to connect a portable screen allows it

to move with it across different parts of the ship.

There are many ideas for using a microcomputer.

Currently, you can find many publications, both

online and book, presenting the possible uses of the

Raspberry Pi microcomputer. Some of them could

also be used on merchant ships.

7 CONCLUSION

The meteorological station project created in this

work can find its application on merchant ships. As

shown in the paper, sensors available to each user can

present measurement data with values comparable to

those obtained by certified equipment intended for

commercial ships.

This is not the only possible use of a

microcomputer, Raspberry Pi is constantly being

improved. In the future, its computing power may

increase, and the amount and current consumption

may decrease. Therefore, finding even better options

for using such microcomputers is a matter of time.

Possible development of the device in the next

phase will allow the creation of further measuring

devices such as, among others, a barograph. Thanks

to the current design, the most important devices will

be located in one place and their values will be

displayed on one screen located in one or many

places on the ship. This will allow you to control the

weather not only from the navigation rooms, but also

from the office rooms and even crew cabins, which

will be able to check the current weather conditions

every day.

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