Subject: Re: [harryproa] Re: Predicting performance?
From: Rob Denney
Date: 5/29/2010, 6:00 AM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

 

Pictures at http://crew.org.nz/forum/viewtopic.php?f=37&t=14046, including an Mbuli.

On Sat, May 29, 2010 at 7:58 PM, Rob Denney <harryproa@gmail.com> wrote:
Sailed on James' junk rigged proa in NZ today.  Went very well.  A solution (not the one used by James, whose sail has a lot of twist) to the sheeting angle conundrum may be to put up a backstay and run the sheetlets to pulleys tied to it.  The sheetlets can then be lead down to the deck and to the helmsman.  Less drag as you have one big bundle, rather than a bunch of little ones, and the pull is horizontal instead of near vertical. 

Also sailed the first of the Chinese built harriettes.  Build quality and finish are top class, the finish in particular is better than any moulded boat, but the boat was not test sailed before it left China so the sailing details were not well sorted.    Nothing that can't be fixed.  Despite this, once I got it going, it was footing as quickly as the bigger, more powerful junk rig. 

rob



On Sat, May 29, 2010 at 1:56 PM, robert <cateran1949@yahoo.co.uk> wrote:
 


I had a good look at the sheeting arrangements. They sheet way back to the stern. This would not really go with the Harryproa configuration of sheeting back to the ww hull. Posssibly sheet back to a pulley midway betweent the two bows. I suspect the hinge would have to be made extra strong to handle the different sheeting arrangements. If the timber wishbones were skinned with some carbon tow, they should handle the extra loads. It would probably be worth it aiming for an optimum leeward shape.
I don't particularly like the wrinkles on the ww side. Possibly cutting the sails on the bias could smooth things.

I am concerned about the sheeting angles. Hopefully Gardner can sort it out before I commit.
regards,
Robert


--- In harryproa@yahoogroups.com.au, Mike Crawford <jmichael@...> wrote:
>
> Robert,
>
> << you could get away with rice bags and still have a reasonable shape>>
>
> Precisely! I'm not sure if it would be a premium racing rig, but
> while cruising, it seems to me that the average sail shape, particularly
> in light winds, would be superior to a bermuda rig.
>
> To get the right sail shape with a single skin takes time, in terms of
> adjusting leech/outhaul/vang (no vang with fixed boom), and money, in
> terms of sail cloth, track, and battens.
>
> Plus, the battens that work at 40 knots will be to stiff for five
> knots, and the battens that work at five knots will be too flexible for
> 40. I'm tired of yanking on my boom to get the battens to switch over
> in light winds. I like to sail, but I'm not the kind of guy who would
> keep three sets of battens on hand in order to have just the right
> strength for the day's winds. So I have a medium-stiff set that
> functions in all winds, but really isn't good for light or heavy weather.
>
>
> <<The strings need not be a big source of drag with dyneema but one
> would need some gloves.>>
>
> Agreed. Though I'd probably try to use dyneema on all the individual
> lines, feeding into a single wider-diameter mainsheet (one shet per bow,
> of course) that would be easier to handle and cleat.
>
>
> <<Some people swear by junk rigs and this makes more sense to me than a
> straight junk.>>
>
> Particularly if you want to go upwind. I'll daysail much more often
> than I go cruising, so going upwind is a big deal. A friend of mine
> says one spends 70% of one's time sailing upwind, and I have to agree.
> If I just go out and back for the day, the windward phase is noticeably
> slower, and covers a lot more distance, than the leeward phase.
>
> - Mike
>
>
> On 5/27/2010 7:29 AM, robert wrote:
> >
> >
> > Hi Mike
> > I am with you on this rig: you could get away with rice bags and still
> > have a reasonable shape; the sheet loads are lighter; it's easily
> > reefable; if the top section rotted out, it would be easy to replace
> > without wrecking the lines of the sails; there's no sail track to buy
> > or jam; and the battens can be low tech. The strings need not be a big
> > source of drag with dyneema but one would need some gloves. I will
> > have to make up my mind before I start trying to set up for making the
> > masts. A simple tapered section makes the most sense and it wouldn't
> > need the bearings of a lot of other rigs.
> > Apart from not being common I am not sure what the problems with it
> > are for a cruising rig. Some people swear by junk rigs and this makes
> > more sense to me than a straight junk.
> > Robert
> >
> >
> >
>



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