By Russ, on February 27th, 2007
VHF radios that conform to the ETU spec have two power settings 1 or 25 watts for fixed sets and 1 or 5/6 watts for handhelds. If you were calling for help especially in a MAYDAY situation you would naturally choose high power so that the Coastguard and as many vessels as possible would here your call.
But using high power for routine calling severely restricts the number of people who can use the few channels available at any one time – in other words several 1 watt conversations can take place within a given area but only one 25 watt
…….Click VHF – Low or High Power on Transmit? …. to continue reading
By Russ, on February 27th, 2007
The fastest sail boat in the world is the Hydroptere. This is an incredible trimaran and if you watch the video on the site below you will see that the hulls barely touch the water – meaning that the whole vessel is virtually flying.
Last month Hydropteré became one of only a handful of sailboats to break the 50-mph barrier, with a run that topped out at 47.2 knots (54 mph) in 25-knot winds. That’s just a knot and a half shy of the absolute sail-speed record of 48.7 knots – but
…….Click Hydroptere – 47.2 knots …. to continue reading
By Russ, on February 24th, 2007
If you have a Radar it will probably be set to use ARPA to assist you in deciding whether you are on a collision course with another vessel . Many yachts have now added AIS to their nav electronics and can overlay the AIS targets on to the Radar and chart plotter display to add more information. So far the logic is that you calculate the Closest Point of approach (CPA) and Time to Closest Point of approach (TCPA) and make a judgement on which way to turn according to the Collision Regs.
SafePass
…….Click Collision avoidance – ARPA , CPA or …what? …. to continue reading
By Russ, on February 24th, 2007
Courtesy of the excellent US Coasd Guard Navigation Site…
http://www.navcen.uscg.gov/enav/ais/default.htm
Picture a shipboard radar display, with overlaid electronic chart data, that includes a mark for every significant ship within radio range, each as desired with a velocity vector (indicating speed and heading). Each ship “mark” could reflect the actual size of the ship, with position to GPS or differential GPS accuracy. By “clicking” on a ship mark, you could learn the ship name, course and speed, classification, call sign, registration number, MMSI, and other information. Maneuvering information, closest point of approach (CPA), time to closest point of approach
…….Click What is the Automatic Identification System (AIS) …. to continue reading
By Russ, on February 24th, 2007
At last Raymarine have produced an AIS receiver – not only that but it combines three other cost saving attributes :
1. It has a built in multiplexor with 2 inputs and 2 outputs which can all be set to different speeds. Remember the C and E series Raymarine chart plotters only have one NMEA port and that can only be set to one speed. If you dedicate this port to AIS then you have to set it to 38,400bd and if it is dedicated to your normal NMEA instruments it would be set to 4,800bd. This new unit from Raymarine
…….Click Dual Band AIS – Raymarine AIS250 …. to continue reading
Most popular posts