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Jim Sexton 10-31-1999 07:00 PM

Radar Proximity Warning Systems
<HTML><!-- eWebEditPro --><P><!--- question body text --->Do you have any information on&nbsp;radar proximity warning systems used by single-handed sailors? <P>Dom</P><P><STRONG>Jim Sexton responds:</STRONG></P><P>Dom, <P><!--- answer body text --->I'm not too sure what radar warning systems most single-handed sailors use. To me, however, the radar proximity alarm and anchor watch option available on most&nbsp;radars would be an invaluable safety device when you are off watch, assuming there is sufficient power available to run the radar for several hours at a time. <P>The Proximity Alarm (Guard Zone) option is a variable range mark (VRM) that you can set to any range on the scope. When a radar return crosses this range mark an alarm is set off. On some&nbsp;radars the alarm is a soft beep and on others a high-pitched squeal. If you are a sound sleeper, it's possible neither would awaken you. If you use this type of radar, I would recommend that you set the variable range mark at a maximum distance equal to one hour's travel time (six&nbsp;nm for six knots) or something less, like three miles which should give you a 30-minute warning for a stationary object. Obviously, if the object is another vessel on a head-on course, the available warning time is much less. On some&nbsp;radars this VRM is also used as an anchor alarm. However, I would prefer to use the anchor alarm on the GPS, since it uses far less power. <P>Another radar warning device is one that detects a radar pulse and sets off an alarm. Unfortunately this type of radar detector does not commercially exist in the marine market. A land based X-band radar detector used to detect police&nbsp;radars is not very expensive and on a vessel at sea would alert you to the presence of another operating radar in time to fire up your radar, search for a return, and determine if there is any danger of a collision. While not very useful in a harbor near land, it should provide some warning at sea. Obviously this type of radar detector would not be of any value to you if the other vessel was operating in the S-band, had its radar in standby mode, or off altogether. The land-based police radar detectors typically operate in the X, K , Ka, and Laser bands but not at all in the S-band. The S-band radar is in the 2 to 4&nbsp;GHz range (2000 to 4000 MHz) while the X-band is in the 8 to 12&nbsp;GHz range (8000 to 12000 MHz). To the best of my knowledge, no one makes a radar detector that operates in the S-band. <P>These are the only radar detection or proximity warning devices of which I'm aware at this time. You must also make it easy for other vessels to see you on their radar in time to take evasive action in case you don't see them. Make sure your radar reflector is installed as high as possible and that you have a spare available, plus an emergency one. <P><!--- name --->Jim</P></HTML>

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