Subject: Re: [harryproa] Re: Rig questions, again
From: "Rudolf vd Brug" <rpvdb@freeler.nl>
Date: 1/8/2010, 5:27 PM
To:
Reply-to:
harryproa@yahoogroups.com.au

 

HI Mike,
 
From what I understand the wishbones are as little and loosely connected to the mast as possible.
The latest version wishbones have a sort of brace on front of the mast, that's all. Windward side rests against the mast. 
http://wharrambuilders.ning.com/profiles/blogs/sailing-with-pha-tiki-30-n119-1 look about 5/6ths down the blog. There are a lot of photos but this one shows the inside of the sail, the wishbones have red spiral wound tubes to protect the mast.
With type of rig you don't want to add things/ropes or whatever, you try to loose as much stuff as possible.
A shunting schooner doesn't seem very handy witth this rig, I agree. It might not be a very good rig for shunting at all as the sheets may get tangled when shunting. A tacking boat only has one set of sheets, but two sets may cause trouble.
I know of at least one (small) shunting proa using a junck rig. So it can be done.
The multiple sheets are the reason the loads are small, replacing them for a boom brings us to the high loaded rig we already had.
Battens could be composite but probably at great cost as there are moving parts, so dimensions are critical.
Wood would be a bit heavier but much cheaper. I don't see rot as an issue here.
The double wishbone as seen in the blog gives a shape that leaves little to ask, in my opinion.
 
regards,
Rudolf
 
----- Original Message -----
From: Mike Crawford
To: harryproa@yahoogroups.com.au
Sent: Thursday, January 07, 2010 10:32 PM
Subject: [harryproa] Re: Rig questions, again

 

Rodolf,

  What are your thoughts on attaching the wishbones to the mast?

  Take a look at the following images:

    http://www.themultihull.com/wharram2/images/bf-05-01-020064.jpg
    http://www.themultihull.com/wharram2/images/jp_6.jpg

  I don't see attachments for each wishbone that would keep it centered on the mast.  It appears that the windward side of the wishbone rests against the mast, with the whole wishbone being prevented from sliding aft by a knotted line. [note: I could be wrong -- the images available are limited]

  There could easily be 12 or more of these wishbones on a single high-aspect rig for something the size of vis.  That could make for a lot of clatter if you've got light wind but choppy seas.  Also a lot of wear and tear on the mast's awlgrip.

  It would be nice if there were a system that could keep the wishbones closer to centered, hopefully with something soft and flexible to cut down on noise and wear.

  I also don't see a way to make an effective schooner rig with those multiple long sheets. 

  Not unless you add a balestron boom and anchor the tack and clew, in which case you'd have a great wing, but would then need stronger sailcloth because the sail itself would be carrying a vertical load.  That might also stress the wishbones too much.  So it looks like one larger sail would be key.

  Also, would it be useful or cost-effective to build the frames in carbon or glass?  Synthetics would be more resistant to rot, but I don't know if there would be other benefits.  Do you think you could save weight over wood, or would wood be largely ideal for this particular purpose? 

  What about the batten end?  You could make a strong argument for a tapered batten that is quite strong and stiff at the joint, but then becomes more flexible to allow a graceful curve.  It would be useful to have something that could take a serious bend without snapping so that the battens don't crack if there's a big gust while running.

  I know you're not the rig's developer, but since you've made more good points in support of its use than anyone else, I thought I'd respond to you.

       - Mike

  

Rudolf wrote:

 

Hi Rob,

You're probably right on building time for bare tube, thing is all the add ons. Like the barbs keeping the boom in place , sailtrack (which was also homemade), hounds, padding for the halyards leads and so on.
And everything has to finished to an exeptable level (well, at least most people do ;)).
Remember this is about comparing an easyrig to others. So we're talking about a balestron boom. An una rig boom would be lighter loaded so less material, and definitely much smaller.
With the swing wing all the extra stuff like the wishbones on the mast are lightly loaded. So it't just a matter of laminating a couple of layers of wood around a simple jig.
I suspect the swing wing would be (much) cheaper to build.
The masts on the Tiki 30 are tapered, hollow wood.

regards, Rudolf


__._,_.___
.

__,_._,___