Welcome onboard!
Also known as the Wheel House and Navigation Bridge
The Bridge is the place where we drive the ship. There are hundreds of buttons to push so it’s “Hands in the pocket area” for engineers and other people coming up for a cup of tea.
So I will now introduce you to the bridge on a ship. I hope you know a little about what’s going on up on the bridge after this tour. And maybe you can understand why everyone coming onboard wants to see the “Commando bridge” Yes it’s true. You never hear any one coming onboard asking: Can I see the paint locker?
No, all visitors want to see the bridge. Now you have a chance for an introduction.
We drive the ship from the bridge. We have a good view from the bridge so we can see other ship coming close to us. We have a lot of equipment to help us to find our way trough narrow waters. It’s important to know where you are all the time. When its fog and we can’t see anything we have radars to help us detect other ships so we don’t collide with other ships.
The bridge with the view over the sea It’s nice when the weather is nice. Believe it or not, but we actually get paid to do this job.
Driving the Ship
When I said that we are driving the ship you are maybe thinking of driving a car. Well, there is a slight difference. In a car you steer with your wheel and step on the gas. On the ship we have an auto pilot and a pitch control for the propeller.
The engine have the same speed all the time and we adjust ship’s speed by the propeller. Autopilot and rudder indicators. Well, we steer a ship by the course on a compass. We know that we have to steer 90° to get from point A to B. Then we just put the auto pilot at 90°. When we want to change course it’s just to turn the knob and the ship change course.
On today’s modern ship we don’t even have to change course. We can program the route from e.g. Skane to Japan and the auto pilot make all the course changes necessarily. Of course there needs to be a Deck Officer on the bridge to watching the equipment. And you can’t program the auto pilot to change course for other ships.
We use hand steering when we are going alongside and when we leave the jetty. Sometimes we use hand steering in narrow water.
Yes, now I hope that you know a little about manouvering the ship and we are ready to move on. There is plenty to see on the bridge.
Position
GPS is a very accurate navigation aid. You can determine your position within 30 - 100 meters precision. The GPS system consists of 24 satellites (21 + 3 spare satellites) in orbit at a height of nearly 20,000km.
You can get your position around the clock every where on the globe.
You get your position by calculating the distance to 3 satellites from the ship. The distance is calculated by measuring the time it takes for the signal to reach the GPS receiver onboard from the satellite.
The speed of the signal is 300,000 km/sec, speed of light. The ships position is at the point of intersection of the 3 satellites.
With a DGPS (Differential GPS) you can get a position fix with the accuracy of less than 10 meter. We need a DGPS receiver onboard to receive the signals from the DGPS land station.
The DGPS land station knows its exact position. The GPS error is the difference between the GPS position and the DGPS land stations exact position. Then the DGPS land station sends the error data to the DGPS receiver onboard.
So the GPS it’s a very useful aid for navigation. GPS gives us the position in Latitude and Longitude. Then we just have to put the position in the chart. A chart is a map. I really don’t know why they call it a chart and not a map. But then if you order a map over Mumbai they give you a map and when you order a chart over Mumbai they give you a map over the port and waterways around Mumbai, very convenient.
But the oldest way of navigation is by the sun, stars and planets. The old sextant comes in handy when you don’t have any satellite navigation system onboard. Or if the system stops working. All officers should know to take sights.
Communication
On a ship we need a radio station so we can reach shore in case of an emergency and to order things.The company also needs to contact the ship so we know where to go. Today they can fit a radio station on a small desk. Back in the days the radio station was so big they needed a special cabin for it. Back then there was a Radio Officer onboard as well. The Radio Officer did all the paper work onboard.
Today the ships have GMDSS stations (Global Maritime Distress and Safety System). GMDSS is a global communication service based on satellites and shore radio stations. Onboard we have a Sat-A, Sat-C, EPIRB, SART, VHF radio and MF/HF radio. We also have a Navtex
GMDSS (Radio) station on a modern ship this is what we need to get in touch with the whole world and a radio telex terminal onboard.
A ship can be in 4 different areas when it comes to radio communication, area A1 - A4:
Before the GMDSS was launched, I think it was 1994, we pretty much had the same equipment onboard. When they introduced the GMDSS all ships got a MMSI (Maritime Mobile Service Identity) number. A new thing that came with the GMDSS was the DSC. That is a radio sending digital codes via radio. So it’s just to enter the MMSI number of the ship you want to reach in your DSC and send. Then they can see that you have called them if they are within range of you radio (and if the operator knows how the DSC works). With the VHF you can reach the horizon, depending of the height of the antennas. With HF you can reach the other side of the world.
Radio telex is not used any more even if the terminal is onboard. Maritex (radio telex) was used .
All this equipment are connected to the GPS so at an emergency it’s just to push a button and the distress signal are sent away to the land station with ships name and position.
Onboard we have a weather facsimile and a Navtex receiver as well. We use the weather facsimile for receiving weather maps, no surprise.
On the Navtex they send out warnings about navigational concerns. The send weather reports and ice warnings and a lot of other information. Sometimes you can receive several meters of messages during a watch.
That was a quick introduction of our communication equipment onboard. Let’s take a look on the stuff we bring on the lifeboat in case of emergency.
A GMDSS ship must have a SART and an EPIRB onboard. The EPIRB sends distress signals to a satellite and then they can see on land where you are and try to save you. When I ship is sinking the EPIRB releases and starts to send distress signals to a satellite. Keep the EPIRB in the lifeboat and they know where you are.
When they are looking for you and the ship comes close to you it’s time to use the SART. The SART transmits signals to a 3cm radar so they can see you on the radar. That’s why all GMDSS ships have to have a 3cm radar onboard.
A 3cm radar is not good for very much except to find a SART. So when you are in the lifeboat you should bring the EPIRB and SART with you.
The Radar
The radar is the most important means of assistance on the bridge. The radar is used to detect ships on the sea by means of signals. The radar antenna sends a signal and when it receives the signal again it calculates the distance to the ship (target). You can see land and everything on the radar screen.
The radar can calculate the speed and the direction the ship moves. It’s easy to do it by your self with a paper and a pen. It’s called plotting. But with many ships on the screen it’s easier to let the radar do the job.
AIS
AIS stands for Automatic Identification System and it was in the mid 80s the Swedish inventor Hakan Lans who developed a technique for spontaneous master less communication for the air industry. It allows a large number of transmitters to send data via radio signals by synchronizing their data transfer to a very precise timing standard.
The AIS transponder is connected to ships GPS and thus have ship position, speed and course all the time. The transponder sends this data via radio to other AIS transponders within range. The transponder decode the data and it’s displayed on a monitor.
All ship have their unique MMSI number which is programmed in the transponder. Now it’s easy to understand that surveillance of ship traffic has been made very easy. e.g. at an oil spill it’s easy for the authorities to see what ship or which ships being at the position of the oil spill.
The transponder have ships MMSI number and receives course, speed and position from the GPS. Before leaving the port we can program the transponder with or cargo, destination and so on. We can send messages to other ship.So when meeting a vessel we can see the name, destination and cargo.
If you enjoyed this listing, please consider to Subscribe to SeafarerJobs.com by Email and get all future listings delivered to you for FREE by email.
