Herb,
Thanks for that input.
I've got a rotating mast on my current catamaran about which I
have mixed feelings. It rotates nicely most of the time, I'm
guessing because of the full battens and solid attachments at the
sail track, so I only rarely have to rotate it by hand. And it does
make a nice entry into the wind.
What if your wing did rotate all on its own? Would you still give
it up?
Not that I like everything about the wing. I still have to adjust
a line to change the angle of attack when going from beating to
reaching to running, and I also dislike having to use a mast
rotation sensor to figure out wind angles.
I'm just confused.
---
I've been sold on fixed masts with the swing-wing right for a
while now, particularly after Rudolph's arguments for it
(simplicity, efficiency).
However, I don't know if I can get the sail area I want, while
still fitting under the ICW bridges, without moving to a schooner
rig, and I'm not sure how the swing-wing would work with two masts.
With a single mast you could use the junk rig sheeting system with
multiple leads going back to a block aft of the beams. But with two
masts, you'd almost need rotating booms, and higher sail stresses,
in order to keep the sheets from interfering with one another.
There's something attractive about going with a standard
fully-battened sail when having sails made, especially compared to a
52' wing sail that no one has really designed before.
So I'm back to pondering the wing masts. Two rotating wing masts
with 60' air draft would produce a serious amount of sail area.
The wing masts might also be better in a storm due to the much
lower drag of an airfoil, assuming they rotate properly. My thought
would be to lock the boom in line with the wing mast and keep the
whole rig feathering with a tri-sail at the aft end of the boom. On
a mooring the booms would be held aft with a bungie fixed to the lw
hull centerline, allowing for some swing without fluctuating too
wildly.
But I'm the first guy to whine about things failing gracefully, or
not failing at all, when things go wrong, and expecting four sets of
bearings and two tri-sails to always work doesn't fit into that
vision. And I'm also not sure if there's a good solution to the
wing masts periodically wanting to sail the boat forward while on
the hook.
So my safety arguments start to make a single fixed mast with no
bearings starts looking a lot better.
Perhaps a single wing sail would do the trick. Less downwind sail
area, but definitely a more efficient driver, so maybe okay at the
ICW bridge height.
The sensible plan would probably be to build a hull that could
switch from a single swing-wing sail to a schooner rig, but if I
want to put anything inside that hull, reinforcements for three
separate masts would get in the way.
So I continue to waffle.
My hope is that someone points out a critical flaw in one design
or the other that makes a definitive choice easy.
- Mike
I have found that the wingmast on งง (ex Sidecar) does not rotate in the wind and is in fact difficult to adjust to the proper angle for sailing. Frequently I forget to adjust it after shunting and go for some time with terrible aerodynamics because it remains at the opposite angle from where it should be, creating a large area of detached flow.
I am unlikely to stay with the wingmast and will probably change it to a wharram type wingsail with luff sleeve that removes the large error. Probably not as efficient as a wingmast at its best, but much more efficient than a wingmast at it's worst.
Best regards
Herb
--- In harryproa@yahoogroups.com.au, "jaythree59" <jaythree59@...> wrote:
>
> Yes, bare poles in a storm or at when away from the boat at anchor.
> A wing needs to be able to be feathered AND also lowered.
> Just how often it actually gets lowered at sea will be something we learn as time on type clocks up a bit more...
> Perhaps we'd learn to feel safe with a wingmast with a "foolproof" bearing system to feather at the jetty or a fore and aft locking position for a mooring.
> For me this may be a moot point if I can get the wingsails sorted well, as they would use circular masts.
>
> Jeff
>
> --- In harryproa@yahoogroups.com.au, Mike Crawford <mcrawf@> wrote:
> >
> >
> > The three-mast discussion brings up a question that's been in my mind
> > for months now: If you want to survive a big storm, is it better to
> > have rotating wing masts or a circular mast section (either rotating or
> > fixed)?
> >
> > My guess is that the wing masts would be better if you're on board the
> > boat in open water, and can ensure they feather into the wind properly
> > in order to benefit from their lower drag. And that circular masts
> > might be better in a mooring field, particularly if you're not on the
> > boat to make sure everything is feathering properly.
> >
> > A big wing mast would be a nice compromise between a single skin sail
> > and a wing sail, with an inexpensive sail that sailmakers know how to
> > design and cut. But I've got an innate fear of the boat wanting to sail
> > while on the hook if it's got a schooner rig with wing masts.
> >
> > Any arguments for one mast section versus the other?
> >
> > - Mike
> >