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Old 27-07-2014, 11:58   #1
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How to Follow Another Sailboat out of Sight?

I'm at a point in a story where I want to have one cruiser, with no limits on electronics or equipment, follow another cruiser at a line-of-sight distance of about 8 miles, or just over the horizon. Is there a way for the trailing yacht to follow the lead yacht without being seen?
Thanks (it's part of a novel)
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Old 27-07-2014, 12:11   #2
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Re: How to follow another sailboat out of sight?

AIS but the other boat needs to be transmitting AIS. they wouldnt be doing that unless they didnt care about someone following them

BUt if the boat ahead is a sailing boat they could be hull down at 8nms but you could still see the mast with good binoculars, only if you basically knew where the boat was... lose sight of it and a mast is hard to see. Or you can still see the sail even though the hull is donw.

Of course radar. If the following boat has a radar up a mast and is hull down it will receive the radar signal but neither boat will be able to be seen.
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Old 27-07-2014, 12:13   #3
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Re: How to follow another sailboat out of sight?

A good radar..
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Old 27-07-2014, 12:14   #4
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Re: How to follow another sailboat out of sight?

Radar
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Old 27-07-2014, 12:23   #5
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Re: How to follow another sailboat out of sight?

A tracking beacon snuck aboard at the last port/anchorage.

Failing that: a drone, a spy satellite, some seriously high quality sonar gear, a dye marker, IR/Thermal imaging gear, or Hansel & Gretel in the aft cabin with an enormous sack full of luminous ping-pong balls.
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Old 27-07-2014, 16:59   #6
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Re: How to Follow Another Sailboat out of Sight?

I don't think radar or radio propagation will work as each requires line of sight.

If you can see his mast, he can see yours.

If one had a transmitter (tracker) attached to the top of the mast of the target boat and the receiver could determine distance, one could conceivable only have the 2 mast tops visible to each other - you'd have to be pretty accurate in controlling distance to remain undetectable.

An HF signal might work but because the signal propagates by bouncing off the ionosphere distance also has to be accurately controlled to receive the signal.

If one had "unlimited" electronics one would purpose a satellite to watch the target boat, like they do in all the movies.

Depends on how much suspicion of disbelief your readers will tolerate.

(PS - I'd go with tracking device on top of his mast and let the readers believe it works.)

http://www.tscm.com/rdr-hori.pdf
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Old 27-07-2014, 17:12   #7
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Re: How to Follow Another Sailboat out of Sight?

Tracking beacon, or some kind of way to spoof their AIS into being on without them knowing like can be done with cell phones etc.
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Old 27-07-2014, 17:18   #8
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Re: How to Follow Another Sailboat out of Sight?

Knowing the boat's destination would be helpful. ... If the chased/followed boat didn't want to be followed, it wouldn't be displaying an AIS signal, would not deploy a radar reflector, and wouldn't be operating its radar.

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Old 27-07-2014, 17:22   #9
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Re: How to Follow Another Sailboat out of Sight?

Is this a theoretical exercise?

Why not just buy a cheapo handheld GPS? Hell for $300 you could probably get two non-mapping ones.
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Old 27-07-2014, 17:28   #10
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Re: How to Follow Another Sailboat out of Sight?

Unfortunately, my steel boat creates a good radar signal, and its paint scheme is visible for several miles, so would not be a good subject in your story. But then, I want to be seen/avoided.

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Old 27-07-2014, 18:33   #11
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Re: How to Follow Another Sailboat out of Sight?

I think the drone idea is best... Its modern! While guy behind observes the guy in front the drone can also be trailing a fish hook...

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Old 27-07-2014, 20:37   #12
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Re: How to Follow Another Sailboat out of Sight?

Just have the boat being tracked running AIS transponder. That will give very long distance tracking ability especially if the following boat has their AIS receiver antenna on the masthead. The following/tracking boat would have to either be receive only or ability to turn off the AIS transmitter. There was a cheap radar detector available in the past. It worked but only gave rudimentary location and tended to be loaded with clutter if there were many boats with radar around. Can't think of the name of it bet seem to remember it gave direction but no distance of transmitting radar signals. This could also act as a warning device for the boat being followed if the following boat is transmitting.

Radar would work but think you'd have to be closer and possibly visible to the boat being tracked to get a decent return. Also, if they have a radar receive capability
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Old 27-07-2014, 20:59   #13
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Re: How to Follow Another Sailboat out of Sight?

Quote:
Originally Posted by Lee Woods View Post
I'm at a point in a story where I want to have one cruiser, with no limits on electronics or equipment, follow another cruiser at a line-of-sight distance of about 8 miles, or just over the horizon. Is there a way for the trailing yacht to follow the lead yacht without being seen?
Thanks (it's part of a novel)
Lee B. Woods
Cocoa, FL
If you want the storyline to take something familiar and make more interesting then stick with Radar and explain "Bending" characteristics of different wavelengths to increase the undetected range.

Obviously your tracker boat needs stealth shapes and camouflage.... But technically there are ways for radar to track 'just' over the horizon

http://www.kelvinhughes.com/marine/r...ls-of-nt-radar


This gives you some military jargon

http://www.agi.com/downloads/support...rine-Corps.pdf
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Old 27-07-2014, 21:02   #14
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Re: How to Follow Another Sailboat out of Sight?

If you are going for tension and conflict... Radar. You can use the lose them in sea clutter and then pick them up again. Get a little too far back and close the distance until they find them again. Rain clutter causing difficulty with the radar returns ect.
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Old 27-07-2014, 21:21   #15
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Re: How to Follow Another Sailboat out of Sight?

VHF with DSC on both boats, set to automatic polling on preprogrammed MMSI's, VHF, GPS hooked up to display, display on charting software which will show DSC targets.

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