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18-08-2008, 12:41
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#1
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S/V rubber ducky
Join Date: Jul 2007
Location: heading "south"
Boat: Hunter 410
Posts: 20,362
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Flies
What's up with flies? How can you have been out on the water for hours, miles from land, and suddenly are getting bitten by flies? And how can they somehow stay right in the open cockpit with the wind blowing across without getting blown away, when you cann't even toss something 3 feet without it going over the side due to the wind?
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18-08-2008, 13:05
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#2
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CF Adviser Moderator Emeritus
Join Date: Sep 2007
Location: Virginia
Boat: Island Packet 380, now sold
Posts: 8,942
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I've been attacked in the middle of the Chesapeake from time to time, but I was really floored when a swarm of them boarded us in the Atlantic Ocean, 25 nm east of the entrance to the Bay. Why in Hell would they fly 25 nm offshore in search of victims?
__________________
Hud
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18-08-2008, 13:12
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#3
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Registered User
Join Date: Aug 2008
Location: Slovenia not Slovakia; gulf of Triest
Boat: owned a 6m single hull sailing boat, a HIRONDELL 23 cat and chartered modern +8m ELAN boats
Posts: 79
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are u sure that flies didn't come from the cabin?
__________________
Rosso di sera, bel tempo si spera. Rosso di mattina, mal tempo si avvicina
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18-08-2008, 14:18
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#4
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Moderator Emeritus
Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
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Quote:
Why in Hell would they fly 25 nm offshore in search of victims?
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It's where the meat is.
I think they can get blown off course and suddenly an island (your boat) is a great place to rest.
__________________
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
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18-08-2008, 14:25
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#5
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Registered User
Join Date: Sep 2006
Posts: 9,398
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18-08-2008, 15:53
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#6
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Registered User
Join Date: Jun 2008
Location: chesapeake bay
Boat: 83 27' hunter "SALTY DAWG"
Posts: 129
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nothing like new england horse flies, boy do they hurt
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18-08-2008, 17:34
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#7
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S/V rubber ducky
Join Date: Jul 2007
Location: heading "south"
Boat: Hunter 410
Posts: 20,362
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Not even horse flies.
On the plus side one of the little f***ers was biting me so hard it couldn't let go fast enough and got smashed. But I still want to know how they do it as it has happened more than once and even on different boats. Maybe they are just attracted to me even from miles out to sea.
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18-08-2008, 17:35
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#8
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Eternal Member
Join Date: Aug 2006
Location: North of Baltimore
Boat: Ericson 27 & 18' Herrmann Catboat
Posts: 3,798
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My mom used to get'em with aqua-net hair spray
Better'n pesticides and it is sport
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18-08-2008, 17:38
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#9
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Eternal Member
Join Date: Aug 2006
Location: North of Baltimore
Boat: Ericson 27 & 18' Herrmann Catboat
Posts: 3,798
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There are few places in the Chesapeake....Cambridge to Crisfield and off of the Menhaden Plants in Virginia.....When Running Tugs down there, we closed up everything for those miles...'cept of course THE ENGINE ROOM!!!!!!!!!!!!!!!!!
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26-08-2008, 16:06
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#10
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S/V rubber ducky
Join Date: Jul 2007
Location: heading "south"
Boat: Hunter 410
Posts: 20,362
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As an update, was out in the same general area last weekend (2 weeks after the orginal "fly"). Had made a 2+ hour crossing of the bay and looked up and saw this HUGE horse fly walking across the main sail. Was kind of amazed that it could hold on during close hauling and reaching. Lost track of it after about 1/2 hour. But this time I thing it came from a cable laying platform that I got within about 150 yards to.
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26-08-2008, 17:12
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#11
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Moderator Emeritus
Join Date: May 2007
Location: Ohio
Boat: Now boatless :-(
Posts: 11,580
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You just discovered the boundary layer. At the molecular level the air at the surface of the sail is not moving at all - spooky - LOL....
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27-08-2008, 01:39
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#12
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,129
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Quote:
Originally Posted by Ex-Calif
You just discovered the boundary layer. At the molecular level the air at the surface of the sail is not moving at all - spooky - LOL....
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See also: The Aerodynamics of Sail Interaction ~ by Arvel Gentry
http://www.arvelgentry.com/techs/The...nteraction.pdf
or
“Telling Tales” at:
WB-Sails Ltd
Flow separation & boundary layers
When the wind sweeps past the sail, its velocity near the sail surface decreases because of the friction. This so called boundary layer can be over 2 inches thick in the middle on the windward side and in the leech on the leeward side of the sail. When the velocity of the air stream decreases to a certain point the boundary layer separates from the sail. The telltales indicate how the boundary layer is behaving at different moments in different parts of the sail. The separation of the boundary layer always means a significant loss in power and is to be avoided at all cost. This is why the telltales are so useful, and why we try to trim the sail so that they always stream steadily aft...
More excellent articles about Aerodynamics from WB-Sails:
WB-Sails Ltd
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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27-08-2008, 02:24
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#13
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Registered User
Join Date: May 2003
Location: New Bern, NC
Boat: Prout Manta 38' Catamaran - Sunspot Baby
Posts: 1,521
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In the Southeast, traveling the ICW in the late spring, especially marsh areas, requires a hefty fly swatter in an open cockpit. We have worn out several - one of us at the helm while the other swats. These aren't horse flies, some locals have told us they are "green biting flies." Smaller, available in the hundreds, and hungry.
We tried the water in the ziplock bag thing, doubled over and run through a bimini support. The water in plastic is supposed to disorient their vision. Not enough to do much good if any.
Entlie
(Traveling with George and using his laptop - I know I could log in but it's early morning and I'm not awake yet)
Sailing Catamaran Sunspot Baby
__________________
She took my address and my name
Put my credit to shame
Sunspot Baby, sure had a real good time
Bob Seger
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27-08-2008, 06:57
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#14
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Moderator Emeritus
Join Date: May 2007
Location: Ohio
Boat: Now boatless :-(
Posts: 11,580
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Quote:
Originally Posted by GordMay
the boundary layer separates from the sail. The telltales indicate how the boundary layer is behaving at different moments in different parts of the sail. The separation of the boundary layer always means a significant loss in power and is to be avoided at all cost.
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So if the fly can stick to the sail you are sheeted to tight?
You want that boundary layer blowin' that buggah right off!
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27-08-2008, 10:42
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#15
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Registered User
Join Date: Sep 2007
Location: Annapolis, Bahamas
Boat: 1983 Gulfstar 36
Posts: 1,253
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If you are cruising the Chesapeake beware of the target ship east of Cape Lookout. I thought they were birds. We had a "Alford Hitchcock " sceen for about an hour.
When the sun starts down and the temp cools they like to land on the underside of the Bimini or on the overhead in the main cabin for the residual heat. Approach them from below with A cup of soapy water with suds and as they drop to try to get airborne they hit the suds.
__________________
Will & Muffin
Lucy the dog
"Yes, well.. perhaps some more wine" (Julia Child)
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