Downhaul used as vang too?

[wtarzia]

Hello -- I posted this on the designs/plans forum and no one seemed to notice. I want to try one more time in case this is the better forum to get an answer. Apologies if anyone is miffed about cross-posting. -- wt

--------------------------------------
Last year I started my "cat-ketch rig windward problems" thread as I put two Wooden Boat Store lugs to my 16 foot single-outrigger canoe. I previously reported 'getting to windward' issues (and standing lugs were all new to me), some of which I improved with good downhauls and better habits. I probably still need better yards (proper taper and bendiness) and perhaps stays. Right now I am wondering if moving my downhauls a little aft along the boom might aid sail shape as they provide some vanging force.

This is the critical part of this thread-question, but I provide background info below if it seems necessary. -- Wade

Background info -- The cat-ketch set up proved to be fast-sailing and interesting in handling possibilities (the rig in some ways takes care of you), though I could not get to windward beyond a close reach (I do have a reasonable leeboard with an attempt at true foil shape, though not perfect), and after using your various tuning hints, I doubt I improved that, if anything, to 55 degrees off the wind. Other people suggested I would need a jib to do better. I learned to live with it, since fast reaches got me where I wanted to go (in any event I left and returned to ramp under sail power).

Improvements I have not had time to do yet are making yards with perfect diameter, taper, and bendiness (right now they are somewhat tapered D. Fir, probably rather stiff).

This season I may reluctantly add stays because the windsurfer masts bend quite a bit in a 15 mph winds, perhaps not helping sail shape (they would put draft into the sails, right?, and let peak fall off?), though I really loved that the stayless boat took only 20 minutes to set up and launch. Stays will also require a short outriggers on the side opposite the ama to get stay angle. :-(

[wtarzia]

Not sure how your rig looks, but moving the down
haul out on the boom with cause the boom to ride
up the mast when the sheets are loaded hard.

It would work with a fixed goose neck.

--- Good point. I have boom jaws with the downhaul running up through them, so that would have to change. --Wade

[Todd Bradshaw]

The primary function of a vang is to reduce upper sail twist when sailing off the wind, so I don't see any way it's going to help with the problem you mention. It wouldn't likely even come into play in terms of trying to get the boat to point higher. At the same time, moving the downhaul aft may reduce luff tension, which is not something you want to happen when trying to get upwind.

As a side note, too much mast bend on a lug tends to further reduce your luff tension. It's very unlikely that you could do anything to make your mast too stiff for the job and that's one of the problems with using sailboard masts. They get their stiffness from being pre-bent by the sailboard's boom system and are never left to be bendy composite tubes in their designed use. Convenient as they may be compared to building a real mast, when you take them out of context they often don't work all that well. You are trying to push a much bigger boat than a sailboard with a bendy mast, yet you have far less control over the mast's shape than you would on a board.

"Probably rather stiff" is a pretty good place for your lugsail's yard and boom to be as well. There is certainly at some point, the ideal stiffness and taper for these spars on this particular boat for the majority of conditions that you personally tend to sail in. It would be the all-round best compromise, since sometimes you might want them slightly stiffer than other times. These "ideal" spars would be stiff enough to hold their shape, and the sail's designed draft, in moderate conditions and while sailing off the wind and then flex a little bit in the right places to reduce draft somewhat and flatten the sails when sheeted in hard and sailing upwind - and they would do it best in the conditions which you tend to sail in the most.

There really is no formula which will determine the desired shape/flex/stiffness to do this on one-off boats. Even a simple, mass-produced boat like The Sunfish has had multiple sailshape tweaks over the years to try to match the sail to the flex of the spars and arrive at the best compromise (since their yard and boom are just tubes, all the adjustment must be done to the sail itself, rather than the spars or both spars and sail). In general, for both their boat and your boat, the more flexible the yard and boom, the more unpredictable the sailshape (and control of it) becomes, which isn't usually a good thing. Given the choice, having the spars a bit on the stiff side is usually a better bet than spars built to flex much.

It's difficult to sit here at a desk and try to determine what might or might not make your boat point higher. Even with the boat and water available for testing, it could take a lot of experimentation and the results are uncertain at best. It's a multihull and many of them don't point all that well to start with. Others will do it, after a fashion, but tend to do it slowly and inefficiently enough that you are better to bear off, sail farther but get there sooner.

Various things might improve your upwind sailing, but none are no-brainers and none are a sure thing (including adding a jib, adding shrouds, etc.). I can tell you though, that adding a vang or softening up your yard and boom are most likely two things that will not contribute to improving your upwind performance.

[Yeadon]

The way the rig is balanced probably has a bit to do with it all, too. As in, center of effort versus the center of lateral resistance. I've tweaked my a bit over the last year or so and it has made a big difference in windward ability.

[Thorne]

Sounds like it would be easier to build new masts with the correct amount of flex for the boat and sails.

Todd B. had a diagram showing a method of running the main sheet underneath along the boom, then through a block attached to the gaff jaws, down to a block on the mast, then back to the cockpit.

This pulls the whole boom and gaff down the mast when sheeted in hard, giving a basic vang action.

Here is a jury-rigged version of same on my dory skiff -- the extra coil of line was just for testing.
http://www.luckhardt.com/boomrigged2.jpg

[wtarzia]

...Various things might improve your upwind sailing, but none are no-brainers and none are a sure thing (including adding a jib, adding shrouds, etc.). I can tell you though, that adding a vang or softening up your yard and boom are most likely two things that will not contribute to improving your upwind performance.

--- Thanks, that all makes sense and is well explained. I am coming to agree that the pile of windsurfer masts I bought at a very good price were not the nice time-saving solution I had hoped, though perhaps they do make pretty good booms. I made a wooden mast for my first proa by laminating two Douglas Fir 2x4s and planing round ~2.75 inches and slight taper, then glassing over, and though it did indeed bend when stressed (as any mast would do I guess), it was much stiffer than my 2.125 windsurf masts. Time to go back to wood. I just got a used windsurfer sail, so it will be interesting to raise it on its yard/mast off the wooden stub mast (Hawaiian rig) and see what happens -- an interesting windward performance comparison. -- Wade

[wtarzia]

How much body does your sail have when close hauled?

It may be too fat?? 0r too fat too far out.

--- Well, it has the body of a new standing lugsail sold by Bohndell (sp?) Sails. I am for practical purposes a beginner sailor, and I cannot well answer your question. FWIW, I don't perceive any obscene amount of camber in it close-hauled. I do not know how to judge twist, and that worries me. (And never sailed with new sails or commercial sails before I bought these last summer -- just old sails and self-made tarp sails). I suppose I need to study a zillion photos of good and bad set lug sails, or spend a few days with an expert.

As far as letting the sails out goes, surely on this skinny hull I have no real sheeting base on the tack where the ama is to windward -- thus, bad twist? On the tack with ama to leeward, I can loop the main sheet around the aft ama and get some better sheeting base. I could alleviate this situation if I extended the "bare"side of the canoe hull with outriggers serving to support a side-seat/stays/sheet. The boat sails so well with the ama to leeward that I have not had to hike out there, so I've been slow to add those outriggers. (And the boat stows as-is in my garage and on my trailer at 7 feet wide and a few inches, another reason to be slow to add more outriggers, which would have to be designed to fold out/back, like Joe Henry's "Flaquita" outrigger; my set-up time with the stayless cat-ketch is 20 minutes, jealously loved!).

The poor mizzen sail has zero sheeting base (the sheet turns on the stern-post more or less, as if I were using a boomkin). It does have to be sheeted in harder than the main when close hauled (back winding) of course, or vice versa, the main cannot quite be sheeted in as it would be on a sloop or cat rig.--Wade

[wtarzia]

Sounds like it would be easier to build new masts with the correct amount of flex for the boat and sails.

Todd B. had a diagram showing a method of running the main sheet underneath along the boom, then through a block attached to the gaff jaws, down to a block on the mast, then back to the cockpit.

--- That's an interesting sheeting idea. Yes, new masts, especially if new masts could let me do without stays.... but even a a fairly narrow outrigger does seem to put extra stress on masts.--Wade

[wtarzia]

The way the rig is balanced probably has a bit to do with it all, too. As in, center of effort versus the center of lateral resistance. I've tweaked my a bit over the last year or so and it has made a big difference in windward ability.

--- Again, as a beginner, I would have problems analyzing rig balance well. I can say that the boat seems to balance well without messing with the sheeting (beyond what is needed to avoid backwinding the mizzen). I have been warned about over-sheeting the main when close-hauled, or succumbing to pinching when a fast close reach might serve me better -- advice I have tried to enact as best as I could.

My leeboard slides fore and aft 40 inches on capture rails, so that I can adjust for any kind of helm balance. I am using a quarter-rudder (rather Indonesian-ish) that has the slightest of weather helm with my leeboard set about a foot ahead of amidships (I know none of this makes sense without seeing the boat; unsatisfactory photos available at wtarzia.com/outrigger or at Wikiproa.com). -- Wade