[MHml] Series Drogue

[Bill Gibbs]

Peter,
You seem correct about the 1.5 knots w/ Jordon Drogue, however this is a lot
faster than drifting with a para-anchor which usually describes miles per
day of drift.  Backing down on your rudders is always a worry with a bow
device.   And waves over the stern a problem with a stern drogue deployment.
Deployment and retrival of the drogue seems easier than a para-anchor, no
adjustment required for wave spacing.  The Jordon Drogue is the only device
tested to function in breaking waves, which gives it the edge for really
extreme conditions.  Sea room is an issue.
 
With sea room, why not deploy less drogue and shoot for 5 knots of boat
speed, or 10 knots, or even match wave speed?  Going faster than the waves
is the problem, and running into the one in front. 
 
I have very little sailing experience in these conditions, and none with
Drogues or Para-Anchors, though I have owned both.  Our one hairy experience
was racing in 35+ knots TWS with 12-15' steep seas.  We had reefed down to
the max and couldn't keep below 18 knots, sailing very deep, which was too
fast.  We had a full bow stuff, sterns rising, rudders out of the water,
etc.  Scary, but ony 15% of a pitchpole.  Bare poles was next, but
conditions abated.  Just a glimpse of what a real gale must feel like.  A
jordon drogue ready to deploy would be nice.
 
But I'm not sure about "from the bow".
 
Bill
Afterburner

  _____  

From: multihulls-bounces at steamradio.com
[mailto:multihulls-bounces at steamradio.com] On Behalf Of Peter Lillywhite
Sent: Thursday, November 23, 2006 6:29 AM
To: Informed discussion of multihull issues
Subject: [MHml] Series Drogue


Bill, my reading of the Drag Device Data Base is that a Jordan Series Drogue
is a medium pull drogue which slows the vessel to very low speeds typically
in the region of 1 to1.5 knots. The author states 'All of the vessels using
this approach lay essentially dead in the water'. Accounts of its use refere
to especially reinforced companion ways to withstand wave impact, not to my
mind suitable for a multi. It seems to me that an oversize series drogue
deployed over the bow may hold a multi head to wind and seas. My own
interest has been allong the lines of a mini series drogue to stop a running
cat from surfing at dangerous speeds.
 
Cheers Peter.

----- Original Message ----- 
From: Bill Gibbs <mailto:BillG at GibbsCAM.com>  
To: 'Informed discussion of multihull  <mailto:multihulls at steamradio.com>
issues' 
Sent: Tuesday, November 21, 2006 11:31 PM
Subject: Re: [MHml] jordan drogue


The value of a Jordan Drogue is that it has been well tested as a drogue,
that is a device to trail and reduce the speed of a boat to manageable
levels.  It has not been tested as a sea anchor, that is a device to hold a
boat bow to wind and waves, while holding station.  As a parachute anchor
does.

 

Your idea of building a sea anchor from a Jordon Drogue concept is
interesting, but way over my ability to know how successful it will be.
Nothing I'd want to bet my life on.

 

But if I had to guess, I'd guess that the Jordon cones quickly lose strength
and stiffness as they increase in size.  I'd also guess that a Jordon drogue
would need a hell of an area increase to move up to sea anchor from it's
current drogue status.

 

Bill

 

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