Conference unifix::sailing

Interesting you should ask....

Less than a month ago, I spent an afternoon with John Walker, founder and 
chief designer of Walker Wingsail Systems.  I'd wrangled an invitation to 
go for a sail on ZEFYR, the 30' prototype (pictured on the next-to-most- 
recent issue of Multihulls Magazine), but alas they had problems the day 
before, and she was hauled up on the dock.  Seems an EPROM was defective 
from the manufacturer, and in their testing they'd discovered the slight 
chance of an open loop.  Given that the system is computer controlled for 
all normal operation, that was unacceptable, so a fix was in progress.

I did see Planesail in construction, and saw wing panels of all sorts in
every stage of construction.  Those from the freighter Ashington (?) which
used them to great advantage for over a year were in the building, as were
smaller ones specifically for the 48' Planesail and the 30' Zefyr.  *Very*
well thought out and constructed.  They build them as you'd expect an
aircraft to be built.  For instance, once all the welding is done on the
aluminum sub-structure and all the holes drilled, etc, the entire wing is
taken out for heat-tempering and then returned for more work.  It looks
quite light (Zefyr's whole rig is about 150 kg) but they've clocked winds
over 100 kts with zero damage.  In fact, all the wingsail systems have
considerably less drag than similar height spar sections with standing
rigging.  All the standing rigging is internal.  I watched Zefyr's follow 
gusts up to 25 kts as it sat there -- I couldn't hear *any* noise at all, 
and my hand on the hull next to the wing bearing (22" dia) failed to 
detect any vibration or sense of mechanical activity.

There's much more to recount than I'll bother with in this reply, but 
suffice it to say that while I think he's not square on the money in terms 
of his accommodation plan (but I could be wrong; he's done a lot of market 
research), his technology is fascinating, and likely to influence yachts 
all over the world in years to come.  Zefyr sails in Plymouth Harbor, and 
has been clocked at 10 kts boatspeed in 10 kts true (reaching, of course) 
and 20 kts in 15 kts true.  Perhaps more amazing is that they can sail 
upwind as close as 22 degrees to the true wind in 10 kts calm seas, though 
obviously this is more a maneuvering stunt than practical sailing.

The wing is an articulated design, 1.4m chord for the leading section and
1.1m for the trailing section, followed about 4m further after by a .8m
"vane".  This vane is controlled from the cockpit, and can be angled in
either direction from in-line with the fwd panels.  (It works analogously
to a rudder trim-tab self-steering gear, albeit with a lot of space
between the power panels and the controlling panel.)  The trailing fwd
panel can be angled up to about 30 degrees from the leading panel for
additional thrust.  This creates a nifty slot of ideal proportions, and
triples the thrust.  Zefyr's wing is 11m long; Planesail has two 14m 
wings.  Additional power is achieved by adding panel length (within 
reason) or more panels.  The Ashington had three 18m (?) panels.

Control is simple.  First, yes, there is manual override included.  But 
for the moment, consider what he has created:  A simple "T" stick shift 
lever, very similar to a car's, which is fully upright in the neutral or 
feathered position.  Push the lever fwd and the after vane cocks to the 
appropriate side increasing thrust.  Once optimum angle is reached, 
further lever movement fwd articulated the fwd two panels in the wing, 
adding substantial power.  Interestingly, pulling the lever aft from 
neutral reverses thrust, allowing one to back down very easily and under 
full control.  Yes, the rudder has been designed to take the loads, and on 
the Planesail, he even has a clever interface with the autopilot 
hydraulics to allow a/p control so that rudder loadings won't overcome the 
manual steering.

Power is entirely self-contained.  There are solar panels on the tops of 
the wings and connecting struts (on multiple-wing designs), and batteries 
built right into the lower parts of the structure.  On Planesail there are 
also two wind generators with feathering props with make it looks even 
mroe airplane-like, and which can be controlled for power as required -- 
by shipboard computer or manually.  It is a power-intensive environment 
belowdecks, but he plans only a small 2-cyl diesel generator in the first 
one, mostly as a back-up and to be sure they have power while they test it 
in actually use.

For some more information, check out the May-June (I think) issue of MM, 
which has a lengthy article about WWS and their boats.  It's somewhat 
lighter on technology than most of us would appreciate, but if you're 
fascinated but not yet familiar with it, this is an excellent intro.

I was *very* impressed by everything I saw, with only a few notable
exceptions.  I'd expected to find a possibly somewhat Mickey Mouse
operation or folks living in some Dreamland somewhere.  (The Brits do have 
a bit of a rep for the eccentric oddball here and there.)  Hardly.  I will
definitely keep in touch with Mr. Walker, as I think he may become quite
well-known in the future for this work.  No it's not traditional in any
form, but traditional boats are only one of several ways to enjoy sailing,
right? 

J.

    Mr. Spencer, you are a find! Please keep us appraised of your contact
    with Mr. Walker. I'm sure a lot of people are interested after that
    article in Multihulls, I certainly am.
    
    I'm very surprised to hear about the low drag on the wing assembly,
    because one of the things that concerned me was windage.
    
    Also, I'm curious about the forces on the base of the wing. They must
    be incredible, as there are no wires to guy it. Is there a post through
    the hull? 
    
    I'm guessing that the choice of Trimaran was dictated by the struts or
    structural needs of the wing to keep it rigid. I'm particularly
    thinking about the forces imposed, say, when pounding in high seas!!
    But at least a Trimaran would keep the wing almost vertical.
    
    I guess a Catamaran would be a greater technical challenge for the
    wing, but would probably be better in terms of living accommodation.
    
    Cheers,
    
    Ray
    

More comments:

>>>    I'm very surprised to hear about the low drag on the wing assembly,
>>>    because one of the things that concerned me was windage.

I was surprised, too.  Not so much that it was lower, but that it's so 
much lower.  The wing thicknesses varied from about 15" I recall on the 
Zefyr to about 18" on the Planesail!  Yup, about 1/3 of chord length.  
Walker says they develop a great deal of thrust in the wind ranges most 
sailors choose to sail in (i.e., before sea state becomes the governing 
force) but offer scant resistance when feathered.  BTW, his computer
automatically reduces thrust as windspeed increases, to keep top speed
within relatively easy control -- about 20 kts.  (I presume hotrodders 
could have this feature modified, though we didn't discuss it.  He is more 
interested in safety than speed per se.)
    
>>>    Also, I'm curious about the forces on the base of the wing. They must
>>>    be incredible, as there are no wires to guy it. Is there a post through
>>>    the hull? 
    
Walker was a successful aerospace engineer before this project.  Remember
that it's built like an airplane wing, and imagine the force that would
produce in a dive, for instance.  While I didn't see the full structure
actually holding it together, I did see the bearing.  On Zefyr it's 22"
dia semi-sealed unit (larger on Planesail) with some semi-exotic 1/2" ball
bearings.  He has tremendous confidence in it for yachting use, since a
much larger version survived atop the Ashington without any problems.  He
says that the three main problems for bearings of this kind are direct
stress, speed and vibration.  The last two are non-issues:  speed is very
slow, and vibration virtually nil.  The stress from side thrust is well
within design parameters, since the boat would heel and tip before
approaching the limits.  Shock loads are eased by the fact the whole rig 
is floating in a forgiving (in one sense, at least) medium.  Remember also
that the computer and manual back-up systems are designed to feather it in
particularly strong gusts.  He has no doubts each bearing will last as long
as the boat. 

On Planesail he plans a simple system a bit like a bearing-buddy.  The 
owner should give about 5 strokes on a belowdecks greasepump once each 
week, which will ensure plenty of lubrication is maintained.  All 
components are non-corrosive in seawater. 

>>>    I'm guessing that the choice of Trimaran was dictated by the struts or
>>>    structural needs of the wing to keep it rigid. I'm particularly
>>>    thinking about the forces imposed, say, when pounding in high seas!!
    
There are no struts.  The bearing is all that connects wing to hull.

In that size range, trimarans provide more spacious accommodation without 
looking as much like Siamese twin buses on steroids.  I don't find the
Planesail aesthetics very pleasing to my eye, though I have to admit the
underbody shapes look very slick and efficient, and he has a reason for
every abovedecks design feature.  To fit the interior he feels such a
yacht deserves (we're talking around $400K for production versions here),
it really must be fit into one big "lump". 

>>>    But at least a Trimaran would keep the wing almost vertical.

This is much less important on a wingsail yacht of Walker's design than on 
other traditional boats.  While heel is limited by the multihull design, 
perhaps to � 15 degrees, in fact ocean swells can create quite a bit of 
additional variation in angle.  Due to the fact that there is no sheeting
at all, only a "tail feather" to control thrust, the wing automatically
swings a little as the boat's angle to the horizon changes, maintaining
nearly constant optimum angle to the wind and therefore, thrust.  This, he
says, offers higher average performance than other sheeted systems, even
wingsails.

>>>    I guess a Catamaran would be a greater technical challenge for the
>>>    wing, but would probably be better in terms of living accommodation.

A cat probably would be more of a challenge to support the wing structure.

Opinion, FWIW:  under ~60', a cat either needs separate hull plans with 
open bridgedeck, or suffer an ugly roof over a bridgedeck if you want 6'
headroom.   Walker plans a range of Wingsail yachts once Planesail is 
established, from about 30' up to charter size -- 100' or more, easily.  
Once he looks at larger sizes, perhaps a cat will emerge.  In *much* 
larger sizes, cats become more efficient than tris for given capacity.

J.

    When you give the mast step bearing 5 pumps of grease every week, where
    does the excess grease go? On the deck?
    
    Doesn't sound too good for charter folks in white pants!

>>>    When you give the mast step bearing 5 pumps of grease every week, where
>>>    does the excess grease go? On the deck?
    
Good question.  I'd guess that any drippings would fall inside the 
structure's base, perhaps into an accessible drip pan or something, but I
didn't see anything or think to ask.  Zefyr's deck and lower wing 
structure were clean as a whistle, after a couple years in use, so I don't 
think it's much of a problem.

Walker has intentionally sloped the roof of the Planesail just enough to
make sunbathing up there unattractive -- too much potential danger from
wing motion. There's plenty of better lounging available all around the
vessel at deck level.  There's simply no need to go up there, since all 
controls are inboard, through the base of the wing.

J.

BTW, correction to .1:  The May-June issue of MM has the trifoiler on the
cover; it's the March-April issue with Zefyr pictured and the article
inside. 

John Walker is sailing his Planesail (48') across the Atlantic now, 
planning to be at the Annapolis show, and hoping to cruise from New 
England south to meet prospective customers.  I'm in contact with his 
office, and hoping to help arrange a Boston area stop.  And go for a sail, 
of course.  I'll post pertinent info as it develops.

They've added various other plans to the range now, including (this is 
only from memory) the 30' Zephyr, a 33'-er, another larger <40'-er, the 
48' Planesail, and one other which is slightly larger than the Planesail, 
but largely based on it.  At least two versions of Planesail have already 
been ordered.

If you appreciate innovative design and good engineering, and like sailing 
with an open mind, this will be something to see in person!

J.