Handling a yacht expertly under power requires an understanding the propeller effect called "prop walk". The lower blade of a turning propeller rotates in denser water than the upper blade as water density increases with depth thus creating a paddle wheel effect. This has a tendency to push the stern sideways in the direction or the propeller rotation. A right-handed or clockwise-rotating propeller tends to "walk" the stern to starboard when moving forwards. The direction of rotation reverses in reverse gear when the yacht is going astern, with the propeller "walking" the stern to port.
Sunday, 24 July 2011
Friday, 1 July 2011
Yacht Race start
JUNE 7, 2011
Around the Racecourse, Part 3: Starting Made Simple
With the prestart work done and a gameplan in hand, Steve Hunt simplifies the starting game in his third installment of Around the Racecourse. From our April 2011 issue.
By Steve Hunt
Related Tags: Racing | Experts | Article | Fundamentals | Around The Racecourse
In the first two installments of my ongoing series in this space, we’ve learned how to make use of our pre-race warm-up, and how to make a game plan worth sticking to. That’s all fine and good, but only if you can capitalize on that plan with great start. Let’s get to it.
Most successful races begin with a clean start near the favored end, allowing you to sail fast for the first few minutes. While you’re sailing fast, those with poor starts are fading back, stuck in bad air and water. Once they’re done for, the racecourse opens up, and it’s much easier to sail smart and execute your game plan.
I love great starts, and Paul Elvström does too! He once said he puts 90 percent of his “race energy” into the start, knowing that if he shot out ahead of the competition, he gets a rush of excitement and adrenaline, prompting him to hike hard and sail fast. There’s a lot to be said for a confidence boost right away.
Getting a front-row start consistently is easier said than done, but there are definitely rules-of-thumb to follow and “plays” you can use in different situations to help you pull off a good start on a regular basis. These rules are all designed to help you be on the line, with speed, at the gun. That’s your No. 1 priority.
To be on the line, or slightly behind it to be safe, at the gun, it’s necessary to have a good understanding of where the line actually is. This comes from sailing up and down the line a few times before the start, calibrating your eye and from practicing how to accelerate your boat in specific conditions. Your mission should be to become the master of time and distance in your specific boat. Every boat accelerates differently, and conditions play a large part as well.
This understanding is an art form that can only be mastered through practice. The teams I sail with make time and distance practice a fun exercise. We are always challenging each other to guess how long it will take get from where we are to a specific point, such as the pin end of the starting line, a lobster pot, or channel marker. For example, I might say, “OK team, how long will it take to sail from here to the pin? I’m starting my watch now, and I’m guessing 43 seconds.” Then, everyone guesses, and the closest one wins. It’s fun, challenging, and a great way to get everyone in tune with time and distance.
We also practice starting before the actual start, giving ourselves a 2-minute sequence and setting the goal to “win” the pin or boat, whichever end we are near. The goal is to be at full speed, sailing closehauled for at least a second or two before the virtual starting signal, and have the bow hit the line with perfect timing. If we don’t nail it the first time, we do it again.
Once you feel comfortable with where the line is and your time and distance abilities, getting a good start is only matter of positioning your boat in a space that allows you to execute your skills.
What’s the best way to find an open space on the line, one that allows you to accelerate and hit the line with full speed? I recommend a port-tack approach. With a port-tack approach you’re sailing against the grain because the majority of boats are on starboard during the final minute before the start. While sailing on port, you can scan the line looking for open spaces. Don’t just look in your immediate area. Scan the entire line to spot less congested areas. By sailing against the grain on port-tack, more spaces will become available to you, where as, if you’re buried in a starboard-tack group, with everyone creeping toward the line, the scenery rarely changes, and you have fewer options.
On your port-tack approach, spot your destination and tack into the space, tacking underneath a starboard tacker and briefly luffing to develop more space to leeward. This will be your runway to accelerate when the time comes. A useful trick is to pretend you’re going to keep sailing past the starboard tacker, not making eye contact or heading up toward them, and then tack at the last second from almost astern of them. Doing so keeps the starboard tacker from defending against you and gives you a strong hidden (from the race committee that is) position to leeward with maximum runway between you and the starting line. If time is running down and no one is coming to steal your hole, it’s now just a matter of accelerating and having accurate time and distance.
Defensive Plays
If nearby boats try to poach your hole, you have to fight to protect it. Typically, boats try to steal your hole in one of two ways. They come from behind on starboard or use the port tack approach. It’s easy to get involved with the boat to windward and lose sight of others approaching, but you have to keep a vigilant watch and be aware of your surroundings. This is a great time for crewmembers to help by looking around and communicating potential threats to the skipper (maybe assign one person exclusively). The key is to defend your hole before you lose it.
On one of the more successful teams I race with, Alan Field’s Melges 24 team WTF, we’ve made up names for hole poachers: bogeys and sharks. Bogeys are port tackers and sharks are coming from behind on starboard. By naming these intruders Alan knows exactly where to look when we notify him. I may say, “Potential shark coming,” or “Bogey coming in hot.”
If a shark is approaching, bear away, and match their speed before they hook you to leeward. While reaching in front of them it sometimes helps to tell them to go above you and point to the hole you just created. Once they head up, you then luff up, pinning them, and re-creating as much of a runway as possible for your acceleration.
Another technique to defend against sharks is to sail across your hole toward the next boat to leeward, making your hole much less appealing and possibly too small for the shark to fit. Ideally you make the hole just less than a boat width, but no smaller. Often the shark will be discouraged and continue sailing looking for a bigger hole. After using this technique you have to work hard to develop a hole to leeward again. A tight main and loose jib will help you climb to windward as much as possible before bearing away to accelerate. You now have a smaller hole than before but at least you have some room to get moving. If you get hooked late in the sequence, you’re in serious trouble.
When a port-tack bogey comes lurking, bear away early and aim at them, or aim at the space you envision them tacking into, putting them in a tough spot under the rules. By aiming at them and sailing fast you force them to tack before they want to, or bear way and duck you looking for an easier hole to steal. Use the speed you generated by bearing away to luff hard, maybe slightly past head to wind (as long as you don’t foul anyone), to create as much of a hole to leeward as possible.
The more crowded an area you initially find, the greater chance there will be poachers trying to steal your hole. The bigger the space you find on your port-tack approach, the better.
Important Rules of Thumb
When you are sailing back and forth in the last few minutes looking for lesser congested areas and timing out your final approach, keep your options open to tack or jibe. Slow down or speed up to break overlaps with boats preventing you from tacking or jibing. You can slow down by swerving or luffing sails.
During your final approach a trailing boat can be a serious threat. When jibing onto port for you’re your final approach, pick a space where no one will be close behind. If someone is following you close astern, they have the option of tacking under you as you tack under a starboard tacker, thereby claiming your hole. A nice move when someone is close behind you, which usually catches them off guard, is to luff head to wind quickly with a hard turn. Usually the trailer will keep sailing past you, at which point you can bear away and now you are the trailer. Finally, avoid stopping completely if you can. It’s best to keep some flow over your blades and sails during the final 30 seconds, especially just before you accelerate. Doing so helps you get up to speed much faster.
Tying it all together
During your pre-race research you sailed up and down the line a few times using a line sight, getting a feel for the line. You also practiced a few accelerations at a mark to calibrate your time and distance for the conditions. You have played the time and distance game with the crew so your time and distance estimates are fairly accurate when estimating which open spaces are available to you on your final approach. As time is winding down in the sequence you are keeping your options open to tack or jibe while sailing back and forth. Now in the last minute or so you execute the port tack approach, making sure there’s no one on your tail, and you find a sweet open space. You position yourself in the open space by lee-bowing a starboard tacker from a deep position almost near their stern. You and your crew stay alert and aware of any poachers, using defensive plays against them. Now it’s just a matter of putting your boat on the line, with speed, at the gun.
Around the Racecourse, Part 3: Starting Made Simple
With the prestart work done and a gameplan in hand, Steve Hunt simplifies the starting game in his third installment of Around the Racecourse. From our April 2011 issue.
By Steve Hunt
Related Tags: Racing | Experts | Article | Fundamentals | Around The Racecourse
In the first two installments of my ongoing series in this space, we’ve learned how to make use of our pre-race warm-up, and how to make a game plan worth sticking to. That’s all fine and good, but only if you can capitalize on that plan with great start. Let’s get to it.
Most successful races begin with a clean start near the favored end, allowing you to sail fast for the first few minutes. While you’re sailing fast, those with poor starts are fading back, stuck in bad air and water. Once they’re done for, the racecourse opens up, and it’s much easier to sail smart and execute your game plan.
I love great starts, and Paul Elvström does too! He once said he puts 90 percent of his “race energy” into the start, knowing that if he shot out ahead of the competition, he gets a rush of excitement and adrenaline, prompting him to hike hard and sail fast. There’s a lot to be said for a confidence boost right away.
Getting a front-row start consistently is easier said than done, but there are definitely rules-of-thumb to follow and “plays” you can use in different situations to help you pull off a good start on a regular basis. These rules are all designed to help you be on the line, with speed, at the gun. That’s your No. 1 priority.
To be on the line, or slightly behind it to be safe, at the gun, it’s necessary to have a good understanding of where the line actually is. This comes from sailing up and down the line a few times before the start, calibrating your eye and from practicing how to accelerate your boat in specific conditions. Your mission should be to become the master of time and distance in your specific boat. Every boat accelerates differently, and conditions play a large part as well.
This understanding is an art form that can only be mastered through practice. The teams I sail with make time and distance practice a fun exercise. We are always challenging each other to guess how long it will take get from where we are to a specific point, such as the pin end of the starting line, a lobster pot, or channel marker. For example, I might say, “OK team, how long will it take to sail from here to the pin? I’m starting my watch now, and I’m guessing 43 seconds.” Then, everyone guesses, and the closest one wins. It’s fun, challenging, and a great way to get everyone in tune with time and distance.
We also practice starting before the actual start, giving ourselves a 2-minute sequence and setting the goal to “win” the pin or boat, whichever end we are near. The goal is to be at full speed, sailing closehauled for at least a second or two before the virtual starting signal, and have the bow hit the line with perfect timing. If we don’t nail it the first time, we do it again.
Once you feel comfortable with where the line is and your time and distance abilities, getting a good start is only matter of positioning your boat in a space that allows you to execute your skills.
What’s the best way to find an open space on the line, one that allows you to accelerate and hit the line with full speed? I recommend a port-tack approach. With a port-tack approach you’re sailing against the grain because the majority of boats are on starboard during the final minute before the start. While sailing on port, you can scan the line looking for open spaces. Don’t just look in your immediate area. Scan the entire line to spot less congested areas. By sailing against the grain on port-tack, more spaces will become available to you, where as, if you’re buried in a starboard-tack group, with everyone creeping toward the line, the scenery rarely changes, and you have fewer options.
On your port-tack approach, spot your destination and tack into the space, tacking underneath a starboard tacker and briefly luffing to develop more space to leeward. This will be your runway to accelerate when the time comes. A useful trick is to pretend you’re going to keep sailing past the starboard tacker, not making eye contact or heading up toward them, and then tack at the last second from almost astern of them. Doing so keeps the starboard tacker from defending against you and gives you a strong hidden (from the race committee that is) position to leeward with maximum runway between you and the starting line. If time is running down and no one is coming to steal your hole, it’s now just a matter of accelerating and having accurate time and distance.
Defensive Plays
If nearby boats try to poach your hole, you have to fight to protect it. Typically, boats try to steal your hole in one of two ways. They come from behind on starboard or use the port tack approach. It’s easy to get involved with the boat to windward and lose sight of others approaching, but you have to keep a vigilant watch and be aware of your surroundings. This is a great time for crewmembers to help by looking around and communicating potential threats to the skipper (maybe assign one person exclusively). The key is to defend your hole before you lose it.
On one of the more successful teams I race with, Alan Field’s Melges 24 team WTF, we’ve made up names for hole poachers: bogeys and sharks. Bogeys are port tackers and sharks are coming from behind on starboard. By naming these intruders Alan knows exactly where to look when we notify him. I may say, “Potential shark coming,” or “Bogey coming in hot.”
If a shark is approaching, bear away, and match their speed before they hook you to leeward. While reaching in front of them it sometimes helps to tell them to go above you and point to the hole you just created. Once they head up, you then luff up, pinning them, and re-creating as much of a runway as possible for your acceleration.
Another technique to defend against sharks is to sail across your hole toward the next boat to leeward, making your hole much less appealing and possibly too small for the shark to fit. Ideally you make the hole just less than a boat width, but no smaller. Often the shark will be discouraged and continue sailing looking for a bigger hole. After using this technique you have to work hard to develop a hole to leeward again. A tight main and loose jib will help you climb to windward as much as possible before bearing away to accelerate. You now have a smaller hole than before but at least you have some room to get moving. If you get hooked late in the sequence, you’re in serious trouble.
When a port-tack bogey comes lurking, bear away early and aim at them, or aim at the space you envision them tacking into, putting them in a tough spot under the rules. By aiming at them and sailing fast you force them to tack before they want to, or bear way and duck you looking for an easier hole to steal. Use the speed you generated by bearing away to luff hard, maybe slightly past head to wind (as long as you don’t foul anyone), to create as much of a hole to leeward as possible.
The more crowded an area you initially find, the greater chance there will be poachers trying to steal your hole. The bigger the space you find on your port-tack approach, the better.
Important Rules of Thumb
When you are sailing back and forth in the last few minutes looking for lesser congested areas and timing out your final approach, keep your options open to tack or jibe. Slow down or speed up to break overlaps with boats preventing you from tacking or jibing. You can slow down by swerving or luffing sails.
During your final approach a trailing boat can be a serious threat. When jibing onto port for you’re your final approach, pick a space where no one will be close behind. If someone is following you close astern, they have the option of tacking under you as you tack under a starboard tacker, thereby claiming your hole. A nice move when someone is close behind you, which usually catches them off guard, is to luff head to wind quickly with a hard turn. Usually the trailer will keep sailing past you, at which point you can bear away and now you are the trailer. Finally, avoid stopping completely if you can. It’s best to keep some flow over your blades and sails during the final 30 seconds, especially just before you accelerate. Doing so helps you get up to speed much faster.
Tying it all together
During your pre-race research you sailed up and down the line a few times using a line sight, getting a feel for the line. You also practiced a few accelerations at a mark to calibrate your time and distance for the conditions. You have played the time and distance game with the crew so your time and distance estimates are fairly accurate when estimating which open spaces are available to you on your final approach. As time is winding down in the sequence you are keeping your options open to tack or jibe while sailing back and forth. Now in the last minute or so you execute the port tack approach, making sure there’s no one on your tail, and you find a sweet open space. You position yourself in the open space by lee-bowing a starboard tacker from a deep position almost near their stern. You and your crew stay alert and aware of any poachers, using defensive plays against them. Now it’s just a matter of putting your boat on the line, with speed, at the gun.
Thursday, 28 April 2011
Asymmetrical spinnakers jibbing
What about changing tacks?
Asymmetrical spinnakers are generally jibed, not tacked. Start with sail fully loaded. Bear off slowly, easing
the sheet as smooth and fast as you can without collapsing the sail. The trick is to use the sheet pressure to get
the sail out in front of the boat. If you don't get the sail eased out before the boat gets downwind, it will collapse
and fall into the headstay. As the boat passes through dead downwind, release the old sheet completely and take
up on the new sheet. The sail is jibed outside and in front of the headstay. If you have a long enough bowsprit,
and it is blowing pretty hard, you may want to try jibing inside the tack downhaul. No matter which system you
use, turn from a broad reach to a broad reach. Do not stop in the middle of the turn, or you will encourage the
sail to get wrapped around the headstay. The lighter the air, the higher the reaching angle you will need to sail,
both at the outset, and as you exit the jibe. In very light air, you may have to physically help the sail around the
headstay.
Asymmetrical spinnakers are generally jibed, not tacked. Start with sail fully loaded. Bear off slowly, easing
the sheet as smooth and fast as you can without collapsing the sail. The trick is to use the sheet pressure to get
the sail out in front of the boat. If you don't get the sail eased out before the boat gets downwind, it will collapse
and fall into the headstay. As the boat passes through dead downwind, release the old sheet completely and take
up on the new sheet. The sail is jibed outside and in front of the headstay. If you have a long enough bowsprit,
and it is blowing pretty hard, you may want to try jibing inside the tack downhaul. No matter which system you
use, turn from a broad reach to a broad reach. Do not stop in the middle of the turn, or you will encourage the
sail to get wrapped around the headstay. The lighter the air, the higher the reaching angle you will need to sail,
both at the outset, and as you exit the jibe. In very light air, you may have to physically help the sail around the
headstay.
Tuesday, 5 April 2011
Digital Selective Calling
Digital Selective Calling
Jan 27,2010 00:00 by infomar
Digital Selective Calling is the fundamental reason why the GMDSS system is different from what has been available until now. Prior to DSC, most radio calls were initiated by making a voice call to the desired station, and relying on somebody at that station hearing the call and then responding to it. All too often the sheer volume of calls made this an impossible task. On a summer afternoon in popular sailing areas it was not unusual for there to be over 400 calls per hour on VHF channel 16. At best, this made it very tedious, and often impossible, to hear calls meant for you, or more importantly, for anybody to hear a distress call. Clearly, something had to be done.
Initially a partial answer was found by shifting some of the calling traffic off channel 16. In some areas Coast Stations stopped monitoring channel 16 and listened for calls only on their working channels. Similarly, calls to marinas were stopped on 16 and moved to other designated channels. That relieved some of the pressure, but now there was no single channel that everybody was listening to, so vessels missed calls meant for them and distress calls sometimes went unheeded.
On board commercial ships, the problem was even worse. They were not only expected to monitor channel 16, but also 13 for bridge-to-bridge calls, 2182 MHz on MF, and if on the high seas, one or more HF distress frequencies. What a headache - literally! The salvation lay in DSC. The DSC control unit monitors all the required frequencies, and lets the operator know when there is a call for his station, or when there is a distress or other urgent call. Best of all, it does all this in total silence. No longer are we subjected to the continuous cacophony on channel 16 nor the static crashes and bangs on 2182 MHz. Instead, we wait for the phone to ring, as it were.
How DSC Works
How is this miracle achieved? The DSC control unit is somewhat like a pager which alerts the receiving station that there is traffic waiting for them. The name, Digital Selective Calling, goes a long way to explaining how it works.
DSC uses a Digital signal to send a message, via the sending station's radio, to alert the receiver that there is traffic for them, and to tell them where and how to receive the traffic. This DSC message is termed a DSC Call, or sometimes a DSC Alert. The digital message includes several pieces of information which will be displayed on the receiving station's DSC control unit:
1. The Maritime Mobile Service Identity of the sending station. The MMSI is a nine digit number, and it is the DSC equivalent to the call sign, or the 'phone number' of a station. It is issued as part of the GMDSS station licence.
2. The MMSI of the station being called. This can be an individual vessel or Coast Station, a specific group of vessels, or in the case of distress, urgency or safety traffic, to all stations.
3. The priority of the call - distress, urgency, safety or routine. DSC can be used for setting up any type of call, from a Mayday to making a phone call home.
4. For distress calls, the DSC alert can include the nature of the distress, e.g. fire, sinking, explosion, pirate attack etc.
5. For distress calls the position of the vessel is normally included. If the control unit is interfaced to a Global Positioning System receiver, then the position will be added automatically. If there is no GPS receiver connected to it, then the position, and the time that the position was valid, must be keyed in.
6. The requested working frequency and mode of transmission for the traffic. The DSC is only used to set up the call; the actual communication is conducted on another radio channel - distress or working channel as the case may be - and it can be conducted in either voice or telex mode, depending on circumstances.
DSC calls are Selective, because as we have seen above, they can be directed to a selected station or stations. Previously virtually all calls were received by all stations who were in range of the transmission. However, the DSC control unit looks at each call that it receives and determines if the call is addressed to it specifically, to it as part of a group, to all stations, or to vessels in the area where the receiving station is located. When such a call is received then the operator is alerted, usually by a buzzer and an indication on the screen. The information as to where and how the traffic will be sent is displayed on the screen. All other calls are simply ignored.
The last part of the name sums up what DSC is about. It is used for calling another station to advise them that there is traffic for them, and to what channel or frequency they should tune their radio to receive this traffic. When a DSC call is transmitted by VHF, it is sent in F1B modulation, at a speed of 1,200 baud. At this speed, all the data in a DSC Alert can be transmitted in about half a second. On MF/HF things happen just a little slower. The modulation is J2B and the speed of transmission is 100 baud. This results in a DSC Alert on MF or HF taking between 6 and 7 seconds to be transmitted. The DSC control unit transmits the DSC calls through the ship's VHF and/or MF/HF radio. Although installations and equipment obviously vary, the control unit is normally also connected to a dedicated receiver which monitors the DSC frequencies for incoming DSC calls, regardless of to which frequencies the ship's radios are tuned.
Jan 27,2010 00:00 by infomar
Digital Selective Calling is the fundamental reason why the GMDSS system is different from what has been available until now. Prior to DSC, most radio calls were initiated by making a voice call to the desired station, and relying on somebody at that station hearing the call and then responding to it. All too often the sheer volume of calls made this an impossible task. On a summer afternoon in popular sailing areas it was not unusual for there to be over 400 calls per hour on VHF channel 16. At best, this made it very tedious, and often impossible, to hear calls meant for you, or more importantly, for anybody to hear a distress call. Clearly, something had to be done.
Initially a partial answer was found by shifting some of the calling traffic off channel 16. In some areas Coast Stations stopped monitoring channel 16 and listened for calls only on their working channels. Similarly, calls to marinas were stopped on 16 and moved to other designated channels. That relieved some of the pressure, but now there was no single channel that everybody was listening to, so vessels missed calls meant for them and distress calls sometimes went unheeded.
On board commercial ships, the problem was even worse. They were not only expected to monitor channel 16, but also 13 for bridge-to-bridge calls, 2182 MHz on MF, and if on the high seas, one or more HF distress frequencies. What a headache - literally! The salvation lay in DSC. The DSC control unit monitors all the required frequencies, and lets the operator know when there is a call for his station, or when there is a distress or other urgent call. Best of all, it does all this in total silence. No longer are we subjected to the continuous cacophony on channel 16 nor the static crashes and bangs on 2182 MHz. Instead, we wait for the phone to ring, as it were.
How DSC Works
How is this miracle achieved? The DSC control unit is somewhat like a pager which alerts the receiving station that there is traffic waiting for them. The name, Digital Selective Calling, goes a long way to explaining how it works.
DSC uses a Digital signal to send a message, via the sending station's radio, to alert the receiver that there is traffic for them, and to tell them where and how to receive the traffic. This DSC message is termed a DSC Call, or sometimes a DSC Alert. The digital message includes several pieces of information which will be displayed on the receiving station's DSC control unit:
1. The Maritime Mobile Service Identity of the sending station. The MMSI is a nine digit number, and it is the DSC equivalent to the call sign, or the 'phone number' of a station. It is issued as part of the GMDSS station licence.
2. The MMSI of the station being called. This can be an individual vessel or Coast Station, a specific group of vessels, or in the case of distress, urgency or safety traffic, to all stations.
3. The priority of the call - distress, urgency, safety or routine. DSC can be used for setting up any type of call, from a Mayday to making a phone call home.
4. For distress calls, the DSC alert can include the nature of the distress, e.g. fire, sinking, explosion, pirate attack etc.
5. For distress calls the position of the vessel is normally included. If the control unit is interfaced to a Global Positioning System receiver, then the position will be added automatically. If there is no GPS receiver connected to it, then the position, and the time that the position was valid, must be keyed in.
6. The requested working frequency and mode of transmission for the traffic. The DSC is only used to set up the call; the actual communication is conducted on another radio channel - distress or working channel as the case may be - and it can be conducted in either voice or telex mode, depending on circumstances.
DSC calls are Selective, because as we have seen above, they can be directed to a selected station or stations. Previously virtually all calls were received by all stations who were in range of the transmission. However, the DSC control unit looks at each call that it receives and determines if the call is addressed to it specifically, to it as part of a group, to all stations, or to vessels in the area where the receiving station is located. When such a call is received then the operator is alerted, usually by a buzzer and an indication on the screen. The information as to where and how the traffic will be sent is displayed on the screen. All other calls are simply ignored.
The last part of the name sums up what DSC is about. It is used for calling another station to advise them that there is traffic for them, and to what channel or frequency they should tune their radio to receive this traffic. When a DSC call is transmitted by VHF, it is sent in F1B modulation, at a speed of 1,200 baud. At this speed, all the data in a DSC Alert can be transmitted in about half a second. On MF/HF things happen just a little slower. The modulation is J2B and the speed of transmission is 100 baud. This results in a DSC Alert on MF or HF taking between 6 and 7 seconds to be transmitted. The DSC control unit transmits the DSC calls through the ship's VHF and/or MF/HF radio. Although installations and equipment obviously vary, the control unit is normally also connected to a dedicated receiver which monitors the DSC frequencies for incoming DSC calls, regardless of to which frequencies the ship's radios are tuned.
Friday, 27 February 2009
How to avoid typhoon during sailing
When the typhoon approach, the barometer reading drops rapidly.
When the typhoon approch, the wind veers to the left. When the typhoon is leaving you, the wind veer to the right irrespective to which hemisphere you are sailing, N or S.
Tuesday, 24 June 2008
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