Subject: Re: safely using Drogues and Para Anchors
From: Mike Crawford
Date: 2/21/2006, 10:46 PM
To: rob dalton

  Did you read what Jordan wrote about the bridle going through chocks and then to a cleat or winch?  I was wondering about the loading myself, but just figured that I'd put in a large backing plate.  He actually suggests straps on the hull, connected to thimble ends of a bridle using shackles.  Not much chafe in that solution, plus it's probably more likely to survive a huge load.

  I'm also not fully set on rigs.  However, despite my appreciation for the easyrig's ease of use, I'm still predisposed against it because of the 64' height limitation for bridges.  I don't think that I can get the light wind performance I want with a mast of that height.

  I love the schooner for all the reasons we've discussed, but then there's that extra weight and cost.  I like the una rigs, but that wharram looks darn efficient, and also inexpensive (comparatively speaking, of course).  My one big question about it is how to anchor that gaff to a mast with a changing diameter, and do so without chafing the carbon/epoxy, which I'm told does not have high abrasion resistance.

  I'm glad that my boat is at least a few years away.  Not only does this provide more time for Rob, Mark, and the folks on the forum to come up with improvements, it also gives me time to figure out what the heck it is that I want to do.  That's probably the toughest thing.  In many ways it's easier to get a production boat and accept its limitations.  Having complete freedom requires a lot more thought and weighing of options.

       - Mike

rob dalton wrote:
This is a hassle, The line needs to be retrieved , retied witha rolling hitch and let out again. A pair of bridles could make it more comfortable. Tie the one not under tension  then haul in the other untie and let out the extra. You'd get pretty fast at tieing a rolling hitch.
I'd also like to see a comparison between a Wharram rig and a una. My plan so far is to use a schooner wharram type rig with a better shaped gaff. This is a long way off and I'm starting to see some of the advantages of the Easy rig in terms of bow loading.

Mike Crawford <> wrote:

  i agree with you on the drogue system.  Redundant, mechanisms, ease of deployment (just pay it out), better continuous loading, lower maximum loading, quicker response to breaking waves, less likely to foul.  They make it hard to argue for a single large para anchor.  I've never set one myself, but I've read many stories about people who have botched their deployment during really bad weather.

  The only thing I question is the ability to adjust the loading by varying the amount of the drogue line paid out.  Everything I see on the Jordan site shows a fixed bridle going out to lines that then attach to the drogues.


  Your repeated posts over time are slowly infecting me with the wharram rig.  My ideal rig would be a reef-able dynarig, but the dynarig folks are hard to find these days, and I'm not sure if they ever solved the reefing problem. 

  While I'd hate to give up my pretty golden mylar Pentex sails, I'll admit that this is somewhat of a shallow desire.  With the strengths of the wharram rig, it's possible that the stiffness and high modulus of Pentex aren't important.  The additional area aloft, and the shaping from the gaff, combined with the smooth leading edge, could make up for the soft sailcloth.

  I wish it were possible to test a wharram rig versus an equivalent una rig, and then look at the costs.

  I'll post the wharram thing sometime in the next few months (after the trailerable issue).  I just want to wait until I'm quiet for a little while, and also until I've finished reading all the past postings.  I'm slowly getting there.

       - Mike

rob dalton wrote:
I started to realise what I had been doing after an  excessive number of memorial services and that three of the boats I had worked on were on the bottom. It started m ehtinking seriously about safety at sea from an engineering perspective.
To me the series system with continuous loading along the line should give better surge characteristics , be less susceptible to wrapping itself round bits and pieces- as happenned to that bloke trying to kite his way across an ocean, failure of an element is not catastrophic, easier to launch
I think I have come to the conclusion that most modern sailing boats should be attached at the bow if current is their main concern and by the stern if wind is the problem. For a Harry this is not a problem. The long, low rocker hulls means that the boats will respond to the pressure on the bow from the rode, due to oscillating winds, with a damped motion.
I appreciate your damping of the almost acrimonious debate. I am after reasoned engineering for criticism so I can learn and tend to get impatient with liturgy.

Mike Crawford <> wrote:
<<I have been one of those fishermen who have fished in the Tasman sea for a living>>

  Well then, my hat is off to you.  :-)

  I also really like the theory of paying out more or less of the drogue line depending upon how much you want to slow your progress.

       - Mike

Robert wrote:
What I like about the combination of a Harry and a jordan series
drogue is that if you want to slow the boat to almost a stop, ie a
para anchor, then you merely pay out more elements to you get to the
same total area of the equivalent para chute anchor.

There has been derision about anchoring from the stern without a
solid explanation why. On some boats it is quite successful and much
more comfortable in that it reduces yawing.
(I have been one of those fishermen who have fished in the Tasman sea
for a living)

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