Friend of mine was sailing hard to get to shore before dark, did not quite make it, and was running to reach the ramp when he was run up on to from behind by a power boat, apart from a few scratches and a lot of rough words no one was hurt. The power boat said it was level and running blind except for the radar. Heavy overcast, no moon. He said the radar did not detect the small sail boat.If it had the alarm would have gone off. It tested fine after the event. EVEN with the long aluminum mast up 20 some odd feet. Apart from the obvious please, like should not be there, carry a radar reflector, etc. If he was to glue an aluminum foil strip say 3 inches by 10 inches on the sail near the peak, would that square inches of flat surface be enough to change the odds of being seen, the round mast apparently was not enough surface area. I don't know what frequency the radar was on (what band) its the small LCD type, and don't know which band can see the smaller area on a flat plane, again apart from the obvious, wave height, angle of radar to level of water, speed, etc.. The reason I suggested the 3 by 10 inches size is I believe that was the size used to confuse the anti aircraft artillery when night flying over Germany. It didn't look much larger than that.
I doubt that would have any perceptible affect. As I understand it, radar works when the waves are reflected BACK. Although a patch of foil would reflect, most of the time it would be reflecting SOMEWHERE ELSE, not BACK. Hence the design of radar reflectors. Incoming radar signals bounce into the corners and get directed BACK. Some people have stuffed a garbage bag with crinkled aluminum foil but with pretty marginal results too. I think your best results would be had with a bona fide radar reflector or two and securite calls on the vhf and a perhaps a floodlight. Of course around here on Lake Erie most folks would not have their vhfs on let alone even HAVE a radar. Most every year someone plows into a breakwall at high speed. When someone is bent on doing that it's best just to stay out of their way. :-) Tod -----Original Message----- From: montgomery_boats-bounces+htmills=bright.net@mailman.xmission.com [mailto:montgomery_boats-bounces+htmills=bright.net@mailman.xmission.com] On Behalf Of MC Carpenter Sent: Friday, December 03, 2004 10:45 PM To: Montgomery Groups Subject: M_Boats: can not be seen on small radar Friend of mine was sailing hard to get to shore before dark, did not quite make it, and was running to reach the ramp when he was run up on to from behind by a power boat, apart from a few scratches and a lot of rough words no one was hurt. The power boat said it was level and running blind except for the radar. Heavy overcast, no moon. He said the radar did not detect the small sail boat.If it had the alarm would have gone off. It tested fine after the event. EVEN with the long aluminum mast up 20 some odd feet. Apart from the obvious please, like should not be there, carry a radar reflector, etc. If he was to glue an aluminum foil strip say 3 inches by 10 inches on the sail near the peak, would that square inches of flat surface be enough to change the odds of being seen, the round mast apparently was not enough surface area. I don't know what frequency the radar was on (what band) its the small LCD type, and don't know which band can see the smaller area on a flat plane, again apart from the obvious, wave height, angle of radar to level of water, speed, etc.. The reason I suggested the 3 by 10 inches size is I believe that was the size used to confuse the anti aircraft artillery when night flying over Germany. It didn't look much larger than that. _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats
MC Carpenter wrote:
Friend of mine was sailing hard to get to shore before dark, did not quite make it, and was running to reach the ramp when he was run up on to from behind by a power boat, apart from a few scratches and a lot of rough words no one was hurt. The power boat said it was level and running blind except for the radar. Heavy overcast, no moon. He said the radar did not detect the small sail boat.If it had the alarm would have gone off. It tested fine after the event. EVEN with the long aluminum mast up 20 some odd feet. Apart from the obvious please, like should not be there, carry a radar reflector, etc. If he was to glue an aluminum foil strip say 3 inches by 10 inches on the sail near the peak, would that square inches of flat surface be enough to change the odds of being seen, the round mast apparently was not enough surface area.
I don't know what frequency the radar was on (what band) its the small LCD type, and don't know which band can see the smaller area on a flat plane, again apart from the obvious, wave height, angle of radar to level of water, speed, etc.. The reason I suggested the 3 by 10 inches size is I believe that was the size used to confuse the anti aircraft artillery when night flying over Germany. It didn't look much larger than that.
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Practical Sailor did a comparison of radar reflector radar cross sections and concluded that the corner reflector type in the "rain catcher" position was the most effective, the flag and tubular British reflectors were far less effective. With large freighters in the Puget Sound region I worry that no one is looking at their display. I believe most small boat radars are X band (3cm or 10GHz). Dick.
participants (3)
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htmills＠bright.net -
MC Carpenter -
Richard Lane