NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: How far away can you see land
From: Bruce J. Pennino
Date: 2016 Sep 24, 12:01 -0400
Bruce
Bruce
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From: Bruce J. Pennino
Date: 2016 Sep 24, 12:01 -0400
Hi:
It took me a few minutes to find the theoretical equation : Distance to
horizon in nautical miles, D = 1.17sqrt H where H is in feet.
To find distance to an elevated point when you are at water level,
add the D from the height of light/mountain above sea level .
For example: If your height of eye is 12 ft, the distance to the horizon is
about 4.0 NM. If the hill top elevation is 300 ft above mean se level ,
calculate a d = 1.17sqrt 300 = 20.3 nm . Add the two values to get about
24 nm. So theoretically you can be 24 miles away and just see the
hill top. Practically this is only true on a perfectly clear day, and I
imagine sometimes significantly less.
On a recent day I was taking a CN sight from a beach and the clouds
plus haze perfectly blended into the sea and there was no horizon to be
seen through the telescope.
Bruce
From: Bruce J. Pennino
Sent: Saturday, September 24, 2016 11:13 AM
Subject: [NavList] Re: How far away can you see
land
On Cape Cod standing at the Race point visitors Center, El 30-40 ft, on a
clear day I can see the tops of buildings in Boston 50 miles away. With my feet
on the beach at the waterline, I can look across Cape Cod Bay and see the low
hills of Plymouth 24 miles away.
Bruce
From: Gary LaPook
Sent: Saturday, September 24, 2016 3:28 AM
Subject: [NavList] Re: How far away can you see
land
I routinely see Santa Cruz island from Moopark California, a distance of 47 nautical miles. I'm 500 feet above sea level and the top of Santa Cruz is 2300 feet but I can see more of the island than just the top of the mountains.
gl
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