Subject: [harryproa] Re: Rig questions, again
From: "robert" <cateran1949@yahoo.co.uk>
Date: 1/3/2010, 4:01 AM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

 

Hi Mike and Gardner,
Thanks Mike for a very nice precis of the pros and cons. I would love to see the dyna rig get sorted for a proa . Todd's models certainly show possibilities but I want to sail my boat in this life time.
Looking at things dispassionately I also have to come round to the easy rig as a simple rig for the single hander. I am still going with the schooner una with a soft sail and a high curved gaff, as seen on those Brazilian boats, due to wanting to sail in very skinny water. This is not set in stone and will be including suitable reinforcing in th elee hull to enable a conversion if I change my mind (an extra bearing set in the centre would allow a conversion at sea if one mast got severe indigestion) I am also seriously looking at a central leeboard to reduce loads on the rudders but am still waiting on outcomes from the Netherlands.

After a couple of weeks of snorkeling in beautifully clear water, walking, and eating fresh seafood, and I am about to start on Take Two of the Harriette rudder shafts. Take One is extremely strong where it worked- I know what I did wrong, and it has given me confidence that the full sized harry shafts will do the job and reasonable confidence I can get it right with sufficient care. Photos if I get Take Two right. It is a shame that I will have to cover it with paint as the carbon cloth looks very spic. I am also waiting to see how Rob deals with the bearings on Solitarry's rudders before I do the cast. I will do the beam rods before the big rudders as they are less tricky.

--- In harryproa@yahoogroups.com.au, Mike Crawford <jmichael@...> wrote:
>
> 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/jibing/tacking. A pair of 2:1
> mainsheets, one per side, should let you handle sailing with some cam
> cleats and a flick of the wrist, no matter what the wind strength.
> (singlehanding/safety/convenience)
>
> - Ability to instantly depower at any time, on any point of sail,
> regardless of wind direction. (singlehanding/safety/convenience)
>
> - Ability to add a reef or shake one out, on any point of sail,
> regardless of wind direction. (singlehanding/safety/convenience)
>
> - 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/safety/convenience)
>
> - 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/sock variation.
> (general performance)
>
> - 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
> >
> >
>

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