Subject: [harryproa] Re: Swing-wing rig....junk |
From: Mike Crawford |
Date: 5/29/2011, 9:13 AM |
To: harryproa@yahoogroups.com.au |
Reply-to: harryproa@yahoogroups.com.au |
The junk battens are a lot stronger than normal squaretop main
battens, and since each one gets its own sheet, the compression
forces on the junk battens are actually smaller. It would take a
lot to break them.
Of course, you can break any rig running downwind if the wind is
too high. You have to be able to depower the rig and then reef it
when needed.
For the junk, as with an unstayed una or easyrig, you can sheet
out until there's no stress, reef, and sheet back in. As with the
other unstayed rigs, there are no worries about getting pinned
against the shrouds and being unable to reef. But unlike the other
rigs, the junk will be easier to reef and get back underway,
especially if you're the only one on deck and you don't want to
leave the cockpit.
There's a reason these rigs have been used for thousands of
years. At this point, the challenge is to take the advantages of a
junk (lower stresses, easier handling, semi-balanced, easy to
wing-on-wing), and learn how to fine-tune the rig for better
windward performance.
Being able to cut the sail and pockets so that the sail forms an
airfoil, or alternately, go with a double-skinned wing foil, takes
the junk out of the "easy but slow" category and makes it attractive
to people who want speed as well.
- Mike
Doug Haines wrote:
OK, junk saiilors, say you are runmning down wind and it is really blowing hard then on the "wrong" side of the mast you shouldhave thebatten gettingbent across the mast - you could even break it (batten).
--- On Sat, 28/5/11, Rudolf vd Brug <rpvdb@freeler.nl> wrote:
From: Rudolf vd Brug <rpvdb@freeler.nl>
Subject: Re: [harryproa] Re: Swing-wing rig....junk
To: harryproa@yahoogroups.com.au
Date: Saturday, 28 May, 2011, 23:57
Ben,There have been reports from different people using junk rigs saying there is little or no difference between tacks.This can be measured by taking bearings on each tack backed up with GPS. They also claim if there is a difference, the "wrong" tack allows them to sail closer to the wind.Regards,Rudolf----- Original Message -----From: bjarthur123Sent: Saturday, May 28, 2011 3:09 PMSubject: [harryproa] Re: Swing-wing rig....junk
"in actual fact" implies you have quantitative data. to me that means two boat testing. have you compared the favored and unfavored tacks in this way?
ben
> My junk rig has an airfoil shape cut into the panels, with a draft of 1/3 the chord length. A junk rig with an airfoil shape is essentially the same as a big, modern square top mainsail. The only difference really is that the sail does get pushed around the mast on one tack....
> But think about this. On the "favoured" tack with the mast to windward, the sail will set a great shape, but the mast will be exposed to the wind and creating drag. On the so called less favoured tack, the mast is hidden in the shadow of the sail, and creates very litle drag. So in actual fact, there is no noticable drop in performance due to the contact between the sail and mast. Sure it looks a little weird, but who really cares?
>
> Also, the leading edge of a sail is very sensitive to turbulence, and a marconi rig with a mast right at the leading edge of the sail will hurt it's efficiency big time (unless the mast rotates), whereas a junk rig will not.