Subject: [harryproa] re: telescoping again
From: Mike Crawford
Date: 5/1/2007, 5:04 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au


  I'll have to contradict myself after having taken a look at some of the Radical Bay 8000 photos at http://www.smartyachting.com/ .

  They have a swept-back una rig with a self-vanging boom that uses sails with luff pockets on some versions, and the system appears to work well.  It appears that between the arc of the mast and the battens that they are able to properly support the sail for decent shape.  They are going with a soft sailcloth for previously-mentioned reasons. 

  The halyard arrangement seems a bit odd, though.  I'm sure Schionning and company have reasons for running the line outside the sails, but from the photos, it seems as if this would affect sail shape and efficiency in the precise location that the luff pocket is supposed to be helping.

       - Mike



Rob Denney wrote:

 
----- Original Message -----
Sent: Monday, April 30, 2007 9:22 AM
Subject: [harryproa] re: telescoping again

Rob said:
<I am not worried about friction so much as wear on
<the lower mast.

not possible to have plastic where they touch each
other?

<The sail is on slugs in tracks on both the top and
<bottom pieces. Hoist it up the lowered top piece,
<then hoist the top piece, raising the sail up the
<lower piece.

Aha, the outside part is on top. Neat, but then the
flex will be completely odd?

< Boom is bonded to a bearing on the mast. Self <

vanging.

so you can rotate it relative to the mast? Then the
track is starting to sound desireable.

But to me a luff pocket seems way less difficult.
It can be D section, by which the outer section would
be stronger since there is a straight shear web?
And the inner can be on top, then both can be tapered.
And the halyard and telescope line could be the same?
Here:
http://farm1.static.flickr.com/191/477637200_6c9b9bd9b9_o.jpg
And, if the two got stuck up there, you could still
lower the sail.

 regards,


Rob



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