Hi Mike,
I would say the Wharram would be cheapest, and worst performer.
The big wing mast would be much more expensive then the others. It is
the highest stressed rig in the comparison.
The swing wing is a junk rig with the low loads and lots of sheets.
Junk rigs are great as they have a way of dividing the loads so that
there are no high stressed parts.
So it is not the absence of a boom that makes them cheaper, but the
uncomplicated way of building the parts.
I am sorry to say I never saw such a rig in real life but I expect it to
be very docile when sailing and feathered.
There are junk sail sheeting diagrams around showing multiple sheetlets
being diverted through blocks ending up in one single sheet. That could
solve the complexity when shunting.
Safest on a mooring in a big blow is to lower your mast, and that could
probably be done with this rig as you don't need a rotating mast.
But I think it is more important that when sailing the swing wing will
be much easier to reef because high stress rigs with full battens will
always bind on the mast. Although I must say that BD's ail comes down
quite well.
Efficiency is not defined by the number of sheets on the sail, but the
ease of use combined with performance.
The shape you can have with this type of rig is great, and will be
better in time.
Because the sheets are lightly loaded they are easy to adjust, probably
can be arranged so they don't need much attention.
Hoisting this sail would be a matter of pulling a rope tying it off and
that's it. On many (small) boats you are working a winch just to get the
main up. Tensioning it is loud enough for everyone within a hundred
metres to hear.
That also has to do with efficiency, and wear.
In the end the low stress stuff will outlive everything else. And
probably without much loss of performance.
Again this is based on second hand information, but the Chinese sailed
with these rigs when we were floating around on tree trunks...
regards,
Rudolf
--- In harryproa@yahoogrou
>
> Rudolph,
>
> I had some questions about this rig back in 2008 that no one really
> addressed, probably because there was a heated discussion on the
dynarig
> at the time.
>
> But now that we're talking about the swing wing:
>
> - What costs less? An easyrig with an 800 cm deep wing mast with sail
> track, a normal mainsail, an easyrig with a wharram soft wing sail, or
a
> boomless swing wing? The swing wing saves on the cost of the boom, but
> adds many parts and frames.
>
> - What's safer to have up as bare poles in a big blow or on a mooring?
> The wing mast might create noticeably less drag than the round mast of
a
> soft wing or swing wing, if feathered into the wind, but I have heard
> about boats with bare wing masts starting to sail while moored in
> crowded harbors.
>
> - Given the need for several mainsheets for proper sail shape, what's
> more efficient? A deep wingmast with a semi-self-regulatin
> easyrig boom, a self-regulating soft wing, or a swing wing?
>
> - Which would be easier to shunt? Do you think one could rig up a
> series of blocks to allow the several mainsheets to feed into one?
>
> - What's most reliable? Fewer parts are better, such as with the soft
> wing, but less drag creates less structural wear-and-tear, such as
with
> the swing wing.
>
>
> What do you think?
>
> I want the true airfoil of a double-skinned sail, but I'm timid enough
> to want to see someone else implement it on a proa first.
>
> ---
>
> Other swing-wing links:
>
> http://www.dunnandd
> (see top-view drawings 1/4 of the way down the page)
>
> http://www.woodenbo
> (see a bottom-view photo 1/3 of the way down the page)
> (posted by Kim in 2005!)
>
> http://www.themulti
> (see the side-view photo on the far right)
>
>
> - Mike
>
>
> //
>
>
> Rudolf vd Brug wrote:
> >
> >
> > Hi,
> >
> > I have built two easyrigs and I expected the second one to be built
at
> > least somewhat faster.
> > It wasn't. You might conclude the first one was built efficiently
> > then, but to me it means that they take a lot of time to build.
> > Especially the boom. Also I would like to see a much simpler rig.
> > A freestanding non rotating mast, as little boom as possible, and a
> > sail configuration that controls it's own shape.
> > Mike mentioned the junk rig, and it's (lack of) performance. But
what
> > about the Swing Wing rig? See
> >
http://wharrambuild
n119-1
> >
<http://wharrambuild
-n119-1
> > Soft wing sails may be able to give the performance needed for fast
> > boats. They certainly are simple, low stress and cheap.
> > regards,
> > Rudolf
> >
> >
>