Gardner,
Given the type of sailing you want to do, I'm not sure that attack
angles will be a primary factor in choosing a rig.
From what I recall, you want something that is fast, safe,
cruise-able, and singlehand-able. Of course, that's probably an easy
assumption for most people, but I do have a memory of your wanting to
be able to sail the
boat easily by yourself because your passengers won't always be adept
multihull sailors.
I'd say this trumps all other considerations. A
very fast rig won't make the cut it you can't depower it very quickly,
can't depower it at any angle of sail, can't reduce sail area at will,
at any angle of sail, or have to grind several winches on every tack.
If you want or need to be able to singlehand without it becoming an
gymnastic feat (and all the attention and
effort that would require), I'll posit that the specific optimum angles
of each rig become secondary factors. Most of the rigs will drop from
the short list because they're either slow upwind or they won't
singlehand well.
So the trick is to choose the rig that will do what
you want, then look at optimizing the design.
Given your requirements, which I share, I'd recommend a large-roach
easyrig. I'll
explain why here with some points and then go into detail on various
rig choices. It's a long email, but since I'm thinking about proa rigs
anyway, it will be a good exercise. Feel free to use the delete key if
you're not interested.
EASYRIG
There's a reason why the commercial name for a ballestron rig is
easyrig. If you make sure you've got a large roach, either with a
flattop/battened system or a gaff, you'd get the following benefits:
- No winches while sailing/shunting/
- Ability to instantly depower at any time, on any point of sail,
regardless of wind direction. (singlehanding/
- Ability to add a reef or shake one out, on any point of sail,
regardless of wind direction. (singlehanding/
- Ability to stay depowered, or weathercocked, for extended periods
of time -- such as when you want to reef singlehanded, or perhaps visit
the head. (singlehanding/
- Lots of sail area high up. (light wind speed).
- Good amount of sail area, good leading edge and foil shape with
either a wingmast and sail track or a gaff/softwing/
- No new technology or development required; uses standard
readily-available hardware and sail cloth. (convenience)
POINTS OF SAIL
- Beat and close reach.
If you want to go quickly upwind, you want as much
vertical airfoil shape as you can get, meaning as much vertical leading
edge as possible that has enough sail behind it to create lift. The
ideal shape is an extremely high-aspect wing like that of a sailplane.
A tall una rig, like the solitarry, or a tall dynarig, come
closest to
this ideal. You can also create additional airfoil length by the
addition of a second sail, either with a second mast in a schooner rig,
or with a second sail in the same mast with an easyrig. Both of these
systems add more drag.
- Beam reach.
Any of the rigs mentioned should do well on a beam reach. In
light wind, though, a taller high-aspect airfoil is going to win in
light winds. The foil shape will generate more lift an a sail with a
less ideal shape, and the sail area higher up will put that foil where
there's actually wind.
- Broad reach.
Any of the rigs listed should do well on a broad reach in heavy
wind. In light wind, though, there's still an argument for an ideal
foil shape. On a multihull with enough power, you can tack fast enough
downwind
on a broad reach, with the foils pulling the boat forward, to have a
VMG
downwind that's faster than going straight downwind. It can be a lot
of work in a narrow channel, but it's effective.
- Run.
All the rigs will run well. Lower aspect rigs should be safer and
easier to handle in high winds, higher aspect rigs should be useful in
lighter winds where there's more power higher up.
RIGS
I'll assume we're talking about an unstayed mast in any case.
Anything stayed is going to cost you more, weigh more, require more
boat and and mast structure, force a much longer setup/takedown time,
and introduce dozens
of points of failure in the rigging system.
Once we're unstayed, we've got una rigs and easyrigs, with pinhead,
flattop, and gaff versions of each, junk rigs, and dynarigs. Crab's
claws can be very effective at reaching, but require far too much
effort to be considered for singlehanding.
- Junk.
I love junk rigs, but I just can't see using one on a
performance boat. To go
upwind you need an airfoil shape on the sail, particularly the leeward
side, which will pull the boat forward. But junks tend not to bend
into a nice foil. Just as important, half the time the sail is on the
wrong side of the mast, fighting the nice foil shape and creating
turbulence that a wing leading edge (hard or soft) won't create. The
junk rig
association claims that new
designs are good upwind, but I've not been able to find evidence of
this.
That leaves the junk being most useful for running. It won't be
bad at beam or broad reaches, but without as much lift from an airfoil
shape, it also won't be good. It's more suited for a boat that moves
at six knots max than for a multi that can meet or even exceed wind
speed.
- Dynarig.
The king of all performance rigs. Not much approaches the dynarig
in terms of the lift it generates compared to the drag it creates,
particularly the double-skinned dynarig. It's essentially a real
wing.
But unless you're willing to do the R&D yourself, it may not
be a realistic option. I'm not aware of any commercially -available
and well-tested solutions for reefing, storing the sails, adjusting
angle of attack, allowing the boom-battens to slide up and down a
tapered mast, and so forth. It also might be a real bear to take down
and attempt to transport (with those boom-battens)
Beyond the unsolved R&D items, there are two singlehanding
issues that would worry me.
One is the lack of ability to weathercock
the rig for minutes at a time without generating lift in one direction
or another. If you're alone, or without skilled help, this is a
problem (as is the lack of a proven lightweight reefing system).
The other is the fact that while shunting, the full sail area is
positioned 90 degrees to the wind for a short period of time. Some
people don't mind this. So be it. Personally, I feel that if the sail
is large enough to drive you as quickly as you'd like to go, it's going
to be too large to put 90 degrees to the wind on every tack or shunt.
Being out in big winds in a boat with a BN of 1.9 or higher has a way
of inculcating the fear of an ill-timed gust. A gust, plus a wave,
while the sail is turning through 90 degrees could result in a bad day.
Nothing would touch the dynarig on a beat, close reach, beam
reach, or broad reach (where it could sail instead of be pushed by the
wind). Depending upon the size of the sail, other rigs might beat it
dead downwind; if the sail is large enough for a good run, it might be
too large to use on other points of sail without reefing (because it's
so darn powerful in an airfoil sense).
- Unarig.
The una really is a model of simplicity with a beautiful elegance
to it. You might not find a real-world design as efficient as a tall
high-aspect una along the lines of what Rob is planning to put on
Solitarry. Great foil shape, lots of leading foil edge for lift, lots
of sail area high up, minimal drag. It won't be as efficient as a
dynarig, but then you also don't have to go through the time and
expense of solving the unsolved dynarig issues.
The tall una will excel at everything but a run in larger winds,
where it might be nice to have the same sail area lower down. But in
terms of singlehanding, the downside is having to use a winch on each
shunt.
- Schooner unarig.
Two unas are a nice compromise. About as efficient as a
tall una, the schooner will allow you to carry more sail area with a
lower heeling moment, work with smaller masts (perhaps carry a spare?),
lower loads on each mast, steer with the sails if there's a rudder/foil
mishap, and so forth. That said, the schooner won't have the light
wind performance of the tall una, which has more sail where there's
more wind, and you might need two winches on each shunt. Unless the
loads are light enough for a 2:1 sheet. Which might be possible, given
that the main vertical loads will be handled by the boom or wishbone.
The schooner should work well on all points of sail, but will not
do as well as the una in light wind. In terms of singlehanding, you'll
definitely have two sails to adjust on each shunt, and you might even
need winches. .
- Easyrig.
Already explained.
Works well on all points of sail, requires no new technology, and
is as easy to singlehand as you can get in terms of both safety and
convenience.
CONCLUSION
Thus, I like the easyrig.
I didn't want to like it, much preferring
the schooner for a long time. I wanted as much sail area as I could
get for a given maximum height, plus I liked the look of it. I was
aware of additional sail handling requirements, but I figured I'd avoid
them part of the time by tacking in light to
moderate winds and shunting the rest of the time.
But I've got a lot of tacking to do to get out to open water, and now
I'm not so sure
that tacking will be as easy as I had hoped -- if I want a boat with
maximum tracking ability and resistance to pitchpoling, I'll obviously
have to give up some ease of turning.
So now I'm back to the easyrig. I'm not sure there's another true
competitor if you want to use a proven design with existing hardware to
go fast while singlhanding with safety. Which is not to say that I
don't want to be proven wrong; this is just the conclusion I've reached
so far.
For me, the real question is whether to go with a wing mast, sail
track, and battens, or to try a variation of the wharram gaff-rigged
soft wingsail. The wharram design would cost a lot less, eliminating
the expense of sail track, battens, cars, and high-tech sail cloth, and
give you the max sail area high up. A fully-battened large-roach sail
on tracks, though, is more proven on unstayed masts.
The last I heard, Robert intended to use a variation of the Wharram
rig in his boat, which I really look forward to hearing about. I think
I'd personally go with a curved gaff along the lines of the Norseboats,
which looks more graceful and yields a bit more sail area for the same
mast height. But we'll have to see.
I know that's a long answer to your question, which actually doesn't
answer the question of optimum angles of attack for each rig. But in
the end, if only one or two rigs meet your design goals, the angles on
the others become moot.
- Mike
Gardner Pomper wrote:
>
>
> Hi,
>
> I have been thinking about rigs again, and have gotten myself
confused on the conventional wisdom. From my reading, the marconi rig
is the most efficient to windward, but the junk and gaff rigs seem to
have some advantages off the wind and with ease of handling.
>
> To go with that, it is also commonly said that multihulls get
their best speed to windward by falling off a few degrees and tacking
through wider angles and making up for the extra distance with extra
boat speed.
>
> Combining those two ideas, it would seem that the best rig for a
multihull might not be the best rig for a monohull. Particularly with
the use of carbon fiber to reduce the weight aloft in a gaff rig.
>
> The dyna rig also seems interesting, except for the lack of
weathercocking. I have an idea, of a dynarig where the battens cross
"behind" the mast (to the windward side), so that there is a slot and
the sail can cant fore and aft, so that the largest part of the sail is
"aft" of the mast. The same idea would work for a junk rig, I suppose.
>
> Anyway, my main question, apart from opinions on the above ideas,
is how I learn more about what is behind the conventional wisdom for
each rig type. Are there any "scientific" comparisons of different
rigs, which show lift based on attack angle for each type of rig?
>
> I may cross post this to a general multihull list also, but I
really like to get the opinions of people that I feel I know, by virtue
of having read their posts for so long.
>
> - Gardner
> York, PA
>
>