- Lack of sleep
- Engine cooling and exhaust system
- Life Jackets
- Improvised Light
- Webcam on bord
Despite extensive research, the cause of seasickness, commonly known as motion sickness or kinetosis is not really known. Our brain has to determine the position of our body in space and uses various sensors to do so: the eyes, the organ of balance in the inner ear, receptors in the skin, tension in various muscles, etc. According to today's knowledge seasickness emerges when these different sensors send contradictory information to the brain.
The symptoms can be very different. Some sailors only feel a slight tiredness, while others suffer from nausea, which can occasionally lead to vomiting or even complete apathy. There have been cases in which seasick crew members wanted to jump overboard just to get off the boat. Usually the seasickness subsides after a few days.
There are behaviours that help to avoid seasickness or at least alleviate the symptoms:
- No pressure! A trip should be started relaxed and well rested. In addition, you should not plan too much at the beginning and avoid long night trips, for example.
- Alcohol and smoking promote seasickness. If you start a sailing trip with the hangover from the day before, you will almost certainly get seasick.
- One should dress warm enough, those who are cold have stress and are more likely to get seasick.
- Move aboard with caution, slow and steady. Do not turn your head too fast, this unnecessarily irritates the organ of balance in the inner ear. Rather stay on deck than go inside the boat.
- Before the start of the trip, eat something, but not too much. Studies show that seasickness has something to do with the level of histamine in the blood. Therefore you should avoid foods with a high histamine content, such as canned meat and fish, sausage and offal, mature cheese, sauerkraut, spinach, olives, nuts, vinegar, hot spices, red wine and energy drinks. Less histamine contains, among other things, fresh dairy products, potatoes, rice, sugar, honey and herbal tea.
There are many different means of combating motion sickness, here is a selection. I am not a medical doctor, so the saying "Ask your doctor or pharmacist about risks and side effects" also applies here.
- Scopolamine patches: Work reliably against seasickness, but in Germany they are only available on prescription and have side effects (impaired vision and sensitivity to light). It is stuck behind one (not both!) ears a few hours before the start of the cruise and is effective for about three days. On cruise ships there are the so-called "double glues". They stick the patch behind both ears to be safe from motion sickness and then land at the ship's doctor on account of an overdose.
- Dimenhydrinate is highly effective and is contained in proven preparations such as 'Vomex A' and 'Ratiopharm travel tablets'.
- Arlevert is a combined preparation of Dimenhydrinate and Cinnarizine. Cinnarizine is also very effective on its own, but is no longer available in Germany. The same applies to Meclozin.
- Ginger is traded as a natural alternative to the above medications and has been shown to inhibit nausea. There are high-dose ginger tablets available in the pharmacy.
- Vitamin C inhibits the histamine level and has shown good effects in a study in the German Navy.
- Acupressure band: This is a wide rubber band with a small wooden ball on the inside. It is worn tightly around the wrist so that the ball presses on the acupressure point responsible for sea sickness. Some people swear by it. The important thing is to find the right point.
Lack of sleep
A prerequisite for good mental performance is sufficient sleep. Especially when we are sailing alone, we always have to face this problem and it is important to deal with it. Wrong decisions due to fatigue will have fatal consequences. Sleep deprivation has often been identified as a factor in the investigation of the causes of accidents. Examples are the Reactor accident at the Three Mile Island / Harrisburg nuclear power plant or the accident of the oil tanker Exxon Valdez off Alaska. In both cases the investigation commissions identified sleep deprivation of responsible persons as one of the causes.
Even relatively little sleep deprivation leads to a loss of our cognitive abilities. About a third of the population reacts already after a short night, as it corresponds to a blood alcohol level of 0.6 per mille. In many studies the effects of sleep deprivation have been discussed. Besides long-term health problems such as depression, eating disorders and diabetes type II, various effects on human behaviour have been observed: attention and memory problems, slower reaction times, short failures in perception and attention, daydreams or even microsleep episodes, altered risk behaviour and emotional instability.
People under sleep deprivation often act irrationally. Instead of logical thinking, emotional thinking occurs. Many of them describe their behaviour as "robotic" from a certain level of sleep deprivation. They only react, think and work through rehearsed routines. Nevertheless, the test persons feel themselves to be mentally fitter and more alert, than they actually are. Most people underestimate their loss of performance, but not everyone is equally affected by sleep deprivation. About one third of the patients show only minimal cognitive impairment even after several days of sleep deprivation. According to twin studies, this ability seems to be hereditary. Another one third reacts particularly sensitively to this. Such people should avoid sleep deprivation at all costs, especially if they are working in a profession that requires constant attention in a low-stimulus environment.
At this point I would like to use an example from sailing to show how sleep deprivation is at least partially responsible for for a fatal sailing accident. It's about the Volvo Ocean Race 2014/15, a sailing around the world regatta with intermediate stops. The main sponsor, the car manufacturer Volvo wants to make stops in big cities to draw attention to itself and its products, which is why the total distance of the regatta, 39000 nautical miles, includes about twice the circumference of the earth. The whole race is scheduled for 9 months. The participation in the race is both physically and mentally a great challenge. The slogan of the regatta is "Life at the Extreme".
In order to make the performance of the crews comparable, all participants sail with the same type of boat: length 20.37 m, width 5.6 m, draught 4.78 m, empty weight 12500 kg. Also the equipment such as the sails or the electronic equipment is specified in detail. The crew of the boats consists of 8 men, the only women crew in the race may take 11 persons on board. One crew member the "On Board Reporter" produces reports, videos and pictures that are published on the event's website. For the work on board he is only available to a very limited extent, so that the effective crew size is 7 or 10 persons.
The boat "Vestas Wind", on which we will concentrate in the following, could not start with the preparations until very late in the day, because the agreements with the organizer were concluded comparatively late. Just in the middle of August the "Vestas Wind" was launched, on August 19 the first test runs began and on September 8 the Boat arrived in Alicante/Spain at the beginning of the official preparations. The first "In-Port-Race", for the local audience in Alicante was scheduled for 3 October. Before the boat had to be equipped, tested and accepted. Also last repairs still had to be carried out. For the crew, the race had begun already long before the official start. Up to the official start of the regatta the crew had already been under continuous stress for 6 weeks.
The watch schedule on the Vestas Wind was set by skipper Chris Nicholson so that there were always 3 crew members on deck in a 4-hour watch. Himself and the navigator Wouter Verbraak were exempted from this rule, but this does not mean that the two had longer breaks than the rest of the crew, au contraire. They were so-called "floaters", always there when they were needed. They took care of navigation, weather and assisted in the handover of the guard. Who has ever sailed a longer distance on a sailing boat knows how exhausting it is to maintain such a guard schedule over days and weeks. Especially the night watches are very stressful. You stand at the wheel, stare into the black night ahead, always trying to find the best course. In the free watch, one often doesn't find a restful sleep. Before you can fall asleep you must first must "come down". Inside the boat it is usually loud, the hull regularly bangs into the waves, you are thrown back and forth. From the 4 hours of free watch, body care and food still go off, so that one often feels sleeps when returning back on deck. In this way, it regularly happens that crew members do not have any restful deep sleep during long periods of time. But you can't say that skipper Chris Nicholson and his men didn't know what they were getting into. Many of them had been in a Volvo Ocean Race and had experience in other long distance races. All were young, fit and had lots of sailing experience.
The navigation equipment on board all boats was the same from the hardware point of view. These were systems that can be found on almost all yachts today. Electronic charts are displayed together with the ship's position on a screen, additional information such as heading, water depth, radar echoes and more can be displayed. The charts are not simply images of conventional nautical charts (raster charts), but are derived from a database (vector maps). This has the advantage that you can, for example, change the display as you wish and, depending on selected scale, different details are displayed. If you use conventional nautical charts, you must, for example switch to a small scale map of a harbour to get all details displayed. With the electronic display, you simply "zoom" into the map and the software ensures that you can see all important details.
On 11 October, the first leg of the journey from Alicante to Cape Town started over a distance of 6487 nautical miles. Vestas Wind reached the finish line as 4th in the overall ranking after 26 days, on November 5, 2014. Briefing for the next stage to Abu Dhabi started already on Wednesday the 12th of November, so a stressful week in the port followed, packed with events such as press conferences,Pro-Am Races and parties like the "Life at the Extreme Award Night" where all crew members had to be present. Behind the scenes, there was a lot of work to do, especially for the navigator. Also in 2014 pirates were active in Somalia waters so the race organizers had defined a large area as "No Go Area" in order to reduce the risk for pirate attacks. Roughly speaking, the boats had to stay east of Madagascar, the Seychelles and the 65th degree of eastern longitude. Since the ship positions were transmitted virtually in real time on the Internet and it could be assumed that the Somali pirates also followed the race on the Internet they had to stay out of the reach of their boats. Planning was complicated by the fact, that a tropical storm formed over the southern Indian Ocean which was drifting westward and was about to develop into a full-blown cyclone. The predictions became more concrete in the course of the harbour week and shortly before the start of the stage it was decided to reduce the no-go area a little, to give the boats the option to circumnavigate the storm to the west.
The second stage started on 19 November at 18:00. First there was a strong headwind from southeast with about 35 kt (65 km/h). After two days and the circumnavigation of the Cape of Good Hope, the wind shifted to southwest and the boats fought against the Agulhas current to the northeast. After 8 days a group of 4 boats had sailed about 20 nautical miles ahead and the Vestas Wind led the chasing pack. The leading group was now coming into the sphere of influence of approaching tropical storm, while the pursuers still had weak winds. On November 29th at 14:40, Vestas tacked onto a northern course. Ahead there was an area with shallower depths, the Cargados Carajos Shoals. Skipper Chris Nicholson and navigator Wouter Verbraak were aware of this and assumed that the lowest water depth would not be less than 40 m. Wouter Verbraak went to sleep around 16:00, while the skipper was still on deck and helped out during some sailing manoeuvres. Around 18:21 the sun set, followed by a short tropical twilight, and at 18:45 it was night. Always again the Vestas wind was shaken by rain showers with corresponding gusts of wind. Suddenly it cracked loudly, the boat turned around his vertical axis and lay on his side. They had run aground on a reef at high speed.
At first the men made several attempts to free the boat with sails or engine, but without success. It was not just to get a clear idea of the situation they were in at night. Every wave that come rolling in shook the boat and pushed it further onto the reef. In the end they pulled in the sails under great effort and made a mayday call. The local coast guard and a fishing boat nearby confirmed receipt and promised help, as soon as it got light. They both thought that immediate help in the dark was too dangerous. Skipper Chris Nicholson informed the race control via satellite with the words: "We're on a reef, we're not getting off, we're f...d." . The following night he described as the "worst of his life". The crew discussed various options and decided in the end not to leave the boat and to wait until dawn. In daylight it was easier to get an overview of the situation. Another participant of the regatta, the "Alvimedica" took course to the scene of the accident for possible assistance. She was about 50 nautical miles behind the "Vestas" at the time of the stranding.
Still the boat was thrown back and forth by the waves and began to break apart. Just before 22:00 the batteries were discharged and the contact with the race control in Alicante broke off. The crew prepared for a possible evacuation and climbed on deck. About two hours before sunrise the keel broke and the boat moved even more than before. The crew hoped that the hull would not fall apart completely. Just before 3:00, two hours before sunrise, they decided to leave the boat. In a precisely planned action, the men shimmyed on a line towards the shallow water. Thereby the two life rafts were also deployed and important equipment was taken from the ship. At 5:36 a.m. the Coast Guard of Mauritius approached scene of the accident and took the crew on board.
The main cause of the accident was obviously the fact, that neither the skipper nor the navigator had been aware of the reef but believed that the water depth would be at least 40 m. This was caused, among other, by the inadequate operation of the available navigation equipment. In case the proper zoom level had been used the "Cargados Carajos Shoals" would have been discovered. A better helmsman's lookout would probably not have seen the half-flooded reef at night. Also on the radar the shallows would have been hard to identify in the other echoes, e.g. of waves and rain showers. Of course, at this point it is easy to conclude the observation of the stranding and to blame the skipper, as well as the navigator Wouter Verbraak alone. In a personal statement he says: "I am devastated and still in shock at the severity of our stranding, as I slowly realize that we are safe in Mauritius and have some time to reflect on the events. I made a big mistake. . . . I was wrong. I don't try to make excuses, just give some kind of explanation and answer some of your questions. There is out of this... to learn a lot of lessons."
If one thinks a little further, however, the question arises how such an experienced sailor, can make such a rookie mistake. He has been sailing since his youth, has taken part in countless ocean regattas and owns a university degree in physics. The official investigation report goes into great detail on the technical aspects such as the presentation of the maps, emergency equipment and organization of the race management. In addition, I would also like to discuss the human factors, that may have led to this mistake, although I am stepping into the realm of speculation. The facts show that at the time of the stranding, the crew had already been on duty for over three months and not with an 8-hour day and a free weekend. Moreover, since the start in Alicante, the team had already sailed almost 10,000 nautical miles. Since the start in Cape Town, the men had already been at sea for 10 days, with hard conditions, day and night, with 4-hour watches under primitive hygiene and living conditions below deck after a stressful harbour week in Cape Town. Participation in such a sailing regatta a great honor and opportunity for a professional in this area. Of course, in this environment, little is said about human performance, necessary breaks, exhaustion and possible illness. In an environment of "hard men" Restriction of performance due to lack of sleep or overstress is usually not an issue. The principle is a little offhand, "We're not pussies."
People under sleep deprivation often act irrationally. Instead of logical thinking, emotional thinking occurs. In an experiment 13 volunteers stayed awake for 35 hours, the comparison group kept their normal sleep-wake rhythm. Then 100 pictures with neutral to emotionally extremely stressful motifs are shown to both groups. The sleep deprived group reacted 60% more strongly to the negative emotions in the emotional centre, the so-called amygdala than the comparison group. There was also a coupling between the emotional center and the point in the brain that is responsible for the escape reflex in case of threats. In an other experiment connections between lack of sleep and the immune system have been showed. For example, a team led by the Californian neuroimmunologist Aric Prather gave his test participants a spray dose of rhinovirus. The result, which received much attention in 2015 is, that anyone who slept less than 6 hours in the previous two weeks got a cold four times more often than the others.
Engine cooling and exhaust system
This topic is often treated somewhat neglected and many sailors do not care much about it. Why even as long as everything works. The reason for many engine failures is in this area - I am speaking from my own experience. Only when I had inexplicable water in the motor bilge for weeks, I have intensively studied the system and would like to pass on the most important points here.
The easiest way is to follow the path of the cooling water through our boat, from the inlet to the outlet. I show it here as an example installation, but it is similar on most sailing yachts. The exact design of the system depends also on whether the exhaust outlet on the engine is below or above the waterline.
- Station 1: Seacock
- Station 2: Filter
- Station 3: Cooling water pump
- Station 4: Heat exchanger
- Station 5: Air vent
- Station 6: Water injection
- Station 7: Muffler
- Station 8: Outlet
Station 1: Seacock
Every opening to the outside below the waterline must be closed by a valve called 'seacock', so the cooling water inlet. In contrast to most other seacocks, e.g. for washbasins, toilets, etc., this shut-off valve must be must be open as long the engine is running, otherwise it would not get any cooling water. Experience shows, that most sailors do not touch this valve and let it always opened, for fear they could forget it and the engine would be damaged without cooling. I recommend to close it at least for longer absence or exclusive sailing for several days. Otherwise, if the cooling water hose should be damaged, you will run into a leak without notice. It is best to get used to check immediately after starting the engine water coming out of the exhaust system, to see if there is something wrong in the cooling water circuit.
Station 2: Filter
Behind the seacock, the seawater flows through a filter which separates coarse impurities. One should get into the habit of checking this filter regularly, depending on the area and water quality, it can become clogged with algae or seaweed after a short time. Before opening the filter to clean the strainer, do not forget to close the sea valve.
Station 3: Cooling water pump
The cooling water pump transports the seawater through the circuit and is flanged directly to the engine. Behind the small metal cover, you will find the so-called impeller, a multi-bladed flexible wheel. It should be replaced regularly, usually once a year according to the manufacturer. It is also recommended to have an impeller as spare part with you.
Station 4: Heat exchanger
With very small marine diesel engines, the seawater itself is sometimes used as a coolant and is directly routed through the engine. Bigger engines have their own coolant circuit, which transfers its heat to the seawater in a heat exchanger. This has the advantage that the aggressive seawater does not come into direct contact with the engine. Somewhere near the engine you will find the expansion tank for the coolant, which you should also check regularly for the correct fill level. The question may arise, why the seawater heated by the coolant is not simply discharged overboard at this point, instead of injecting it into the exhaust pipe later. This causes a lot of problems and at your car you would not do something like this at all. The reason is that the exhaust pipe of a sailing boat does not run on the outside of the hull (like on your car), but right through it. If one would not cool down the exhaust gases, the hot exhaust pipes, in contact with fibreglass or wood, would damage the material.
Station 5: Air vent
As already mentioned above, the introduction of seawater into the exhaust system is dangerous, because under certain conditions seawater can flow backwards into the engine via the exhaust. This must be prevented at all costs, because salt water definitely has no place in an exhaust turbocharger or an exhaust valve. A device which should prevent this is the air vent. Is the point of injection of the cooling water into the exhaust system, less than 15cm above the waterline, there is a risk, that when switching off the engine, cooling water can run into the engine via the exhaust. As long as the cooling water pump delivers the seawater under pressure through the air vent it remains closed and everything runs normally. However, if suction is created on the "OUT side" (see picture), the negative pressure is compensated by air flowing in from outside.
Station 6: Water injection
Directly behind the engine, the cooling water is introduced into the exhaust gas flow and cools the very hot exhaust gases down to a tolerable level for the internal exhaust system.
Station 7: Muffler
The "exhaust pipe" on most sailing yachts is a temperature resistant rubber hose. On the way out there is usually a silencer, which has a secondary function to prevent water from outside flowing backwards into the engine. Some boats have a so-called gooseneck, a kind of inverted U-tube, which is also intended to prevent water from outside entering the engine. In principle, the greatest possible gradient between the engine and the outlet is desirable. In this context a tip: After switching off the engine, some water usually remains in the exhaust. This is not a problem unless you crane the boat out of the water and lift the stern more than the bow. Then this residual water can flow back into the engine and, for example, fully develop its corrosive effect over the duration of winter storage. Therefore, when craning the boat out of the water, make sure that the bow is slightly higher than the stern and that all the residual water can run out of the exhaust.
Station 8: Outlet
At this point, the mixture of cooling water and exhaust gases finally finds its way outside. This warm mixture of salt water and combustion residues is chemically quite active, which is why the outlet or 'transom connector' is always made of stainless steel. But you should not forget, that also the fibreglass, wood or aluminium around comes into contact with it too and therefore especially the area around the outlet should be cleaned more often.
Wearing life jackets is important - every reader will surely agree with me at this point. Unfortunately on board many Yachts you can often see crew members and guests running around on deck without life jackets. Therefore, I would like to describe an incident here, that deals with this problem. The information is based on the official investigation report of the "Federal Bureau of Maritime Casualty Investigation" in Hamburg. (unfortunately only in german language)
The sailing yacht leaves the port of Gedser in Denmark in the morning at 10 o'clock, the destination is Warnemünde north of Rostock/Germany. There are four crew members on board, middle-aged men, who have chartered the yacht for one week. Two of them act in the role of the skipper. They both have a lot of experience and are holders of a high-quality licence with which one may also work commercially as a skipper. The other two have little or no sailing experience and help on deck when needed. The weather is good, with wind forces of 4-5 Bft and an average wave height of about 1m the boat makes good progress. Around 13 o'clock the yacht is already 2 nautical miles north of Warnemünde and the skipper decides to catch up the sails and enter the harbour under engine.
To do this, one of the skippers goes to the bow to recover the jib sail. A second crew member follows him and is just amidships when a powerful wave hits the yacht and catapults him overboard. He can still hold on to the railing for a short time, but just as one of the men comes to help him, he loses his grip and falls into the 16° C cold Baltic Sea.
The skipper turns the boat around and they manage to throw a rope towards their colleague floating in the water. He is able to grab that rope, but unfortunately it is not moored on board and therefore no connection can be made with the crew member who has gone overboard. A second attempt to throw a rescue collar fails because the associated line gets tangled up on the reel. In spite of the Baltic Sea "pleasant" temperature and the relatively moderate wave heights, the sailor is out of strength after only a few minutes. At first he drifts face down on the water and then he sinks.
At this point I would like to quote from the investigation report: "As already on the days before, no one on board was wearing one of the existing life jackets or safety ropes."
In addition to the fact that it is not mandatory to wear a life jacket on German yachts, it is at least required by good seamanship. Unfortunately, it's too easy to be seduced: "the land is already in sight..., nothing can happen now...", but how a very experienced sailor once said to me: "You can drown face down in a puddle."
Does this just happen to me? Again a berth neighbor smashed my side light while "parking". Of course not at my home port but far away on a small island in the Mediterranean. What to do? The store for accessories at the port says, that in a week at the earliest he can get the spare part. "A week at the earliest" here means "maybe a month from now, or not at all". So all that helps is improvisation. The next supermarket has mineral water in red bottles - that is the solution. I cut the bottle apart at its constriction and cover the sector of 112.5° provisionally with adhesive tape.
Now I put the socket, which fortunately remained whole, into the lower half of the water bottle and glue it in place. The construct is attached to the boat with sturdy adhesive tape and cable ties. Works better than expected, is not officially approved, but in an emergency..... If I should come into the night on my way home, at least I am not invisible.
Webcam on bord
Many sailors live far away from their harbour and often ask themselves "How is my beloved boat?". For me the Corona crisis was the driving force behind the "Webcam on Board" project. For months the borders were closed, not even a mechanic was allowed to move out and look for the boat.
I have made the following demands on the installation:
- Power supply shall be possible with 12 V and 220 V, depending on whether shore power is available or not.
- The facility should not use harbour's WLAN, but should have its own Internet access.
- The costs are to remain within reasonable limits.
Let's start with the Internet access. I have decided to use a mobile router. It works similar to the router at home, except that it is not connected to the Internet by cable, but uses mobile telephony to connect to data from the Internet. This router is available in the cheap version from about 45 Euro, I decided to use the Fritz!Box 6820 LTE, which however at around 170 euros, is considerably more expensive than the no-name products. I expect a simpler installation and a reliable Operation in the LTE network also abroad. It can also be supplied directly with 12 V without a power supply unit. As data card I use a prepaid card for 10 Euro / month. The Fritz!Box generates a WPA2 - WLAN which can take up to 20 computers in the local network, the complete Networking and monitoring of the boat is therefore no longer a problem. It also has a connection for a LAN cable. The configuration of the router takes place at http://fritz.box via the browser of the computer via which you are connected to your WLAN. Tip: During operation when abroad you have to tick the box for roaming, this is not the case by default.
For the cameras there are basically two options. Either you use a webcam which is connected via USB directly to the computer , or one decides to use a network camera that is logged into the local network and often has its own small web server. For cost reasons I decided to use cheap USB webcams. You also do not need an extra power supply because they are supplied directly via the USB cable and can be attached inconspicuously e.g. with cable ties. The disadvantage is that the cables are sometimes quite short and you may need an extension. Extension cables are available in stores up to 5 meters in length, but that doesn't mean the webcam will still work with the long cable. Therefore I recommend to think carefully before the installation, where to place the computer and the cameras so that the cabling is not too long and cumbersome.
As Computer I use the Raspberry Pi, a popular single board computer, with Linux (Raspbian) as operating system. In the meantime there is a large variety of models of this little all-rounder, I have chosen the Raspberry Pi 3 Model B. It has 4 USB ports for the webcams and WLAN on board, so it can be directly connected wirelessly to the local network. In addition, it offers almost unlimited possibilities for expanding the system. For example, you could monitor the temperature and air pressure , remotely control lights or get the current GPS position e.g. when you rent out your boat. Cost for the model 3 approx. 35 Euro.
The Raspberry Pi normally requires 5 V DC and is supplied with an appropriate plug-in power supply unit. That I can also connect it directly to the 12 V on-board power supply, I equip it with a small circuit board, which allowes a voltage supply between 6 V and 61 V. The board is called "Strom Pi" and costs about 30 Euro in version 2. The version 3 is with approx. 42 Euro a little bit more expensive offers the possibility of a backup battery to ensure the function for a longer time in case of power failure.
When choosing the housing, you have to make sure that the Strom Pi also fits into it. A normal Raspberry Pi case would be too flat. In my case, the finished computer has the following dimensions in millimeters: 93 x 60 x 31, so it fits into every small angle..
The software tells the Rapspberry Pi what to do. The easiest way to do this is to use a simple shell script. For the following tasks you need some "Linux knowledge" or the desire to acquire it. If you dont have anything to do with computers and would like to install a webcam anyway, you can send me an e-mail (email@example.com) and I will send you a current offer for a fully configured Raspberry Pi.
We start with the recording of an image by the webcam using the program fswebcam. The installation takes place in the terminal with
apt-get install fswebcamUsing the simple instruction
fswebcam test.jpgyou already take a JPG picture and save it under test.jpg in the current directory. In this case fswebcam selects the settings automatically and uses only one webcam. If you want to use several webcams and want to change the settings the command becomes a little more extensive. First you should get the properties of the used camera. The command
fswebcam -d /dev/video2 --list-controlsshows you the controls of my Creative Technology, Ltd Live! Cam Sync HD on the video2 port:
Available Controls Current Value Range ------------------ ------------- ----- Brightness -39 (19%) -64 - 64 Contrast 25 (50%) 0 - 50 Saturation 55 (55%) 0 - 100 Hue 0 (50%) -100 - 100 White Balance Temperature, Auto True True | False Gamma 100 (0%) 100 - 300 Power Line Frequency 50 Hz Disabled | 50 Hz | 60 Hz White Balance Temperature 4500 (45%) 2800 - 6500 Sharpness 2 0 - 10 Backlight Compensation 1 0 - 4 Exposure, Auto Aperture Priority Mode Manual Mode | Aperture Priority Mode Exposure (Absolute) 166 (1%) 5 - 10000So you may adjust e.g. brightness and contrast. This is also necessary, because the webcams need different settings depending on the installation location. Especially on the outside the pictures are often overexposed if you don't reduce the brightness. You simply have to try a bit as different manufacturers also have very different default settings and chipsets.
Now we upload the images via ftp to the webserver. This has the disadvantage, that the password is transmitted openly, but its for me the easiest way. For uploading the pictures I use the program curl unlike ftp it works even at ftps without any problems. A shell script for the Rasperry Pi and two cameras could look something like this:
#!/bin/bash CAM1="/dev/video0" Hier den entsprechenden Ort einsetzen an dem die Kamera registriert ist CAM1_BRIGHTNESS=""Brightness=85%"" CAM1_CONTRAST=""Contrast=50%"" CAM1_FILENAME="cam1.jpg" CAM2="/dev/video2" CAM2_BRIGHTNESS=""Brightness=70%"" CAM2_CONTRAST=""Contrast=50%"" CAM2_FILENAME="cam2.jpg" FTPPATH="ftp://10.20.30.40/herberthiesl.de/htdocs/meineBilder/" Das Verzeichnis auf dem Webserver USERPW="user:password" Benutzername:Passwort fswebcam -v -d $CAM1 -s §CAM1_BRIGHTNESS -s $CAM1_CONTRAST -S 5 -r 1280x720 $CAM1_FILENAME fswebcam -v -d $CAM2 -s §CAM2_BRIGHTNESS -s $CAM2_CONTRAST -S 5 -r 1280x720 $CAM2_FILENAME curl -v -T $CAM1_FILENAME -u $USERPW $FTPPATH curl -v -T $CAM2_FILENAME -u $USERPW $FTPPATH
Now you just have to make sure that the above script is executed regularly. This is done by the cron daemon a service who works in the background on Linux computers and performs tasks at given times, such as executing our script. For this purpose you open the cron editor with crontab -e and add the following line for example:
01 * * * * /home/herbert/cam.shThis line would execute the script every hour at one minute past the hour, i.e. take a picture with every webcam and upload it to the web server. /home/herbert/cam.sh must be replaced by the current path to the script, of course. If you would take a picture once a day at 14:30 it would look like this:
30 14 * * * /home/herbert/cam.sh
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