Wednesday, August 15, 2007

Tuesday, August 14th "Icebergs and Radar Problems"

News from Cloud Nine's Captain, Roger Swanson:

We are getting on well, but still having radar problems. We fixed the
antenna problem, but now it won't pick up targets. Fortunately it
worked crossing Baffin Bay where we had fog all the way with icebergs, but
it died yesterday. Some of the icebergs show up on radar, but by no
means all of them so we must be very careful. I'm thinking about
ordering a whole new radar and have it shipped to Cambridge Bay. The problem
is to try to find one in Canada to avoid customs delays.

We expect to reach Peel Sound in the morning and head south. Other
than the fog, weather has been good, very little strong winds. Shortly
after entering Lancaster Sound weather cleared and the icebergs have been
thinning out, practically none now. More later.


Lissa said...

Cloiud Nine has made it farther than before.
Keep it up guys!!!!

dielectric said...

Iceberg ice has very poor reflectivity because the dielectric coefficient is only 3.0 whereas seawater has a complex coefficient with a modulus over 90. Thus if a small iceberg, bergy bit or growler is in sea chop it might not be seen on radar even when within 1000 meters.

However if salt water is soaking a growler (bit of ice sufficient to hole your vessel but only say 1 to 2 meters out of the water) it might be picked up rather well.

These comments are the basis for the continuing admonishment of captains to proceed slowly in fog and the rules established for the Safety of Life at Sea have not changed in this respect.

The work on iceberg detection by radar was that of a current professor at Berkeley 50 years ago when he was in officer International Ice Partol run by the U.S. Coast Guard.