For Greg H Whilley Boat - Balanced Lug Yawl-Rig

[Todd Bradshaw]

This was a tricky one but I think I finally got it to work. Remember that I'm working off of a scanned sailplan/profile drawing which wasn't very good but the centers seemed pretty accurate when I refigured them and remeasured things, so the new plan should be very close to real life. The new rig looks like this:

http://albums.photopoint.com/j/View?u=1302883&a=13888485&p=57146751

The extreme mast rake had to go to get the thing to balance. It put the sail area too far aft. I ended-up with both masts raked about two degrees and their centers are parallel and 9.6' apart. The main mast step stays in the planed position and the partners would have to be moved to change the rake. We have no real choice but to step the mizzen onto the stern stem. It's such a small mast that it should be possible to figure out a small step that fits down in there. The tiller would need to be one of those "bent around the mizzen mast" jobs or a push-pull, steer stick rigged to a yoke. The mizzen could possibly be mid-boom-sheeted to a bridle over the tiller or rigged with a boomkin for more leverage.

Here is how things measured-out and it's superimposed on the former Standing Lug and Gunter Sloop rigs:

http://albums.photopoint.com/j/View?u=1302883&a=13888485&p=57145573

I tried to keep the sail area and overall rig height similar to the other rigs. The new combined C.E. (white) is slightly lower than the originals and the balance (C.E. vs. C.L.P.) is right where we want it to be with a yawl. This combination of things makes very specific, narrow parameters for sail sizes, shapes and their positions on the masts as far as planning goes. On the water, the ability to adjust the helm by over or under-trimming the mizzen should make it possible to fine-tune things as needed. Draft allowances, yard bend, luff curves, etc. have not been figured into the plan at this stage, but should be pretty standard.

[John B]

How much of the rudder to you figure into that clp Todd.

[Todd Bradshaw]

As I was taught, the C.L.P is the fore-and-aft center of everything below the waterline, including that portion of the rudder. Not having one of those fancy yacht design programs or the energy to cover the plan with a grid and count-up square inches and parts of square inches, I did it the old way by printing it out on a big sheet of cardboard, cutting away everything above the waterline and balancing it on a knife edge. It's always seemed to work pretty well and seems to pretty accurately fit with what would be the aparent C.L.P. on the designer's sailplans.

Since we are figuring pressure on the sails vs. resistance to sideslipping of the hull, the rudder is also included as part of that resistance and as part of the "total waterline length" for finding the lead.
The lead is a percentage range of that length adjusted for specific types of sailplans and the forces that they characteristically generate. In this case, a yawl, it's usually best to lead the C.L.P. by 12%-15% of the total waterline length with the sailplan's total C.E.

Naturally, these are generalized design guidelines. In real life, the boat will probably sail far more often with the actual centers much different from the paper plan's centers. Unless the boat has a pretty extreme hull shape though, (long and skinny or short and fat, etc.) they're pretty effective for design work and getting the rig to work.

[Greg H]

Oh wow Todd, Didn't actualy think you would spend time working it. Thank you. http://media5.hypernet.com/~dick/ubb/smile.gif I don't have time for more than a quick look at the moment. The mast rake hmmmm....Well, I'll look at it later, thankyou again.
__Greg

[Chadd Hamilton]

Hey Todd. I have a question: I am building an Acorn Tender and have the mast, yard and boom ready to go-save for a few coats of varnish. Having never dealt with the balnced lug rig, I am in a bit of a bind finding a diagram of how everything goes together. Do you happen to know where I would find such a thing?
Thanks,
Chadd

[Tom Dugan]

Chadd,

Check the WoodenBoat Store for this book

http://www.woodenboat.com/325110.jpg

You'll be glad you did.

-T

[Chadd Hamilton]

Thanks, Tom. It's on my list!

[Howard Gmelch]

Todd, First let me say that I do own your book and I am impressed with the broad scope of your knowledge. However, after seeing the above sketch, I have to ask if you have ever fooled with a lug rig?

Maybe I'm missing something but after all of my messing with lugs, I can't imaging one working well, if at all, with the yard hung abaft the fore and aft center of the yard. One of the best features of the lug is its ability to self tighten the luff as the sheet is trimmed. This is accomplished through the cantilever effect of the yard. How does the luff tension in the rig you drew?
Howard

[Todd Bradshaw]

Blue Earth,
It's pretty simple to rig. The corners of the sail are tied out to the ends of the boom and yard with just enough tension to pull the sail edges taught and then the sail-to-spar lacing is done. It should be snug enough to keep the sail close to the spars but not squashing it up against them. The halyard is tied to the yard at the proper place. I usually use a "rolling hitch" which holds well and doesn't generally slide around on the yard. The halyard runs up through the masthead sheave, block or dumbsheave (glorified hole in the masthead) and down to it's cleat near the mast base.

If desired, you can rig a "parrel" - a small string of wooden beads (craft shops) which keeps the wind from blowing the yard away from the mast on one tack or when raising and lowering the sail. It's not critical in your case, but adds a nice, classy touch. If the sail was to be reefed and the yard hoisted to a lower position on the mast, it would be a really good idea to have the parrel. The masthead area looks like this.......(digging around in hard drive for drawing)....

http://albums.photopoint.com/j/View?u=1302883&a=14083578&p=57162065

When you hoist the sail, it wants to sag down on the aft end, swiveling as it hangs on the halyard. To prevent this and put the sail at the proper attitude, you need something that is attached to the boom and pushes on the aft side of the mast, keeping the sail at the designed angle. This can be done with another parrel, this one tied to the boom, but is usually better off with a single wooden jaw. It may have a small parrel across the forward end, just to keep the boom and mast connected while hoisting sail, but the jaw pushing against the back of the mast is what's doing the real work.

http://albums.photopoint.com/j/View?u=1302883&a=14083578&p=57162066

This also helps keep the sail's luff tight, which is good. So good, in fact, that a simple downhaul, attached to the boom and cleated to the mast is usually worth adding. If you're willing to rig it, you can even combine the mainsheet and downhaul functions in a single line. This forms a self-tending downhaul system. As you sheet the sail in, the downhaul tension tightens. Off the wind it is automatically eased a bit. This type of system really sails well and is used on everything from Sunfish to some of the fastest iceboats in the world.

http://albums.photopoint.com/j/View?u=1302883&a=14083578&p=57162067

The sheet hanging under the boom sometimes tries to strangle you while tacking and the system requires more hardware, but it is often worth rigging since it performs so well.

[Todd Bradshaw]

Howard,
Good observation. Yes, the same thing occoured to me when I was trying to get things to fit the boat. Set up this way, the luff tension is only really being generated by the mainsheet and leech tension. Normally gravity alone puts a lot of tension on the luff and sheeting just adds more.

Not having any construction plans, sections or even a top view of the hull, I was hesitant to move the mainmast step forward blindly, so I drew it out this way. To see if it would work, I hung one up in the back yard today, similarly rigged, to see what happens. Under decent wind and mainsheet loads, it looks fairly normal. As the tension diminishes though, the yard tends to dip and things get pretty strange until the next puff comes. The same thing would happen when tacking, so your initial observations may be more correct than mine. Moving the halyard tie-off and boom/mast intersection points forward about a foot made all the difference in the world and the thing acted like a lugsail again.

In the case of this boat, rigged as a yawl, the sails themselves can't be moved much without really screwing-up the balance, but moving the masts forward (10'-12" main, 6"-8" mizzen) would seem to be well worth doing. The question then becomes one of being able to fit a reasonable mainmast step on top of the bow stem, rather than on the keel. If this can't be done, I think it might be smarter to scrap the yawl and go with a larger, single lugsail.

[Greg H]

Now I've had the opportunity too study it a bit, Nice work! However to my eye the near vertical masts don't suit the shape of the hull. I don't know the structural implications of stepping the main mast on the stem where it joins into the keelson, but if it can be done that would allow a little more rake, wouldn't it? I did some rough drawings using Ian's measurements for the smaller version of the balanced lug. Then I guestimated a sprit boom mizzen using the proportions as the Ness yawl. Moving the main about 8" forward will allow about the same rake, it looks like it might work, at least as far as I can tell http://media5.hypernet.com/~dick/ubb/wink.gif . I'm going over those notes again and I'll post them as soon as I can cram those bits of paper into my computer.

There is one rigged this way in australia, it was at the duck flat site but I can't seem to find it now.
yhs Greg

[Todd Bradshaw]

I found the Ness page with plans and some photos at
http://www.imagic.demon.co.uk/openboat/ness.html

It is a handsome looking rig and I think it looks better than mine does, too. It will work on the Whilly Boat - IF - you can figure out how to step the mast about 14.4" forward of the normal mast step. Otherwise, the C.E. is too far back. I drew it out at about 80 sq. ft. and got it to balance just on the back edge of the 12% Lead Line. With the mizzen for adjusting the helm, it should work fine.

http://albums.photopoint.com/j/View?u=1302883&a=14083578&p=57172747

The mast rake is the same for both masts and the same as that on the original Whilly Plan. I'm not sure how they have the mizzen boom rigged and can't see the photos well enough to see what they've done. A normal sprit-boom would be at a different angle. With that low boom this almost looks like a little Leg-O- Mutton instead. In any case it seems to work. Sail area could be adjusted down a bit if you think 80 sq. ft. is too much (the sloop rig had 80) but it doesn't drastically change the balance or the amount that the mast has to be moved until you make it a really big reduction.

[Greg H]

Thanks Todd,
Visualy, that flows a bit better.
When you say the mast needs to step 14.4" inches forward, are you measuring from the standing lug step which is drawn on the plans or the balanced lug step, that according to notes is about 5" aft?
------Greg

[Todd Bradshaw]

The standing lug step. It's the one shown on the latest drawing as two tan dotted lines and marked "Old Mast Location". By the way, the combined C.E. for the Ness-style rig at 80 sq. ft. is 1/4" aft of, and about 3.5" below the C.E. for the 80 sq. ft. sloop rig. This is with the new sail sizes having the same proportions to each other that they had on the Ness Yawl. Their fore-and-aft separation is a little bit different though to get the rig to balance. The big problem with trying to get the yawl rig to fit the Whilly is trying to get enough height and area in the sailplan vs. how far forward the mainmast has to be moved. Every attempt I made to leave it back near the normal position required seriously downsizing the mizzen (to the point of being pretty silly) to get things to balance.

[Greg H]

It looks like there is room to put a mast step where it needs to be. It works out to be just where the stem begins to curve upward and on the end of the keeson/stem scarf joint.I can notch it over the stem, but a lot of it will be up against the planking and I'm not sure what the implications are of having stress applied to the hull and stem at that point.
She hasn't been turned over yet so I have plenty of time to think about it. I built her at 15'6" increasing the distance between the molds by two inches (I assume that doesn't change the balance in any significant way) but your right, the boat is almost too small.
---Greg

[Todd Bradshaw]

Fifteen-six???....Now he tells me...Slowly I turn...Step by step....Inch by inch... Good thing I'm not a highly paid yacht designer.
There's good news and bad news...
The good news is that it might help fit all that stuff in the boat without having to add a bowsprit to step the mainmast on. The bad news is that it moves the C.L.P. depending on how exactly you stretched it. It also changes the actual distance measurement of the lead, which is figured as a percentage of waterline length. That may, in turn, change the spacing between the masts, possibly in our favor to some extent. Don't drill any holes before we do a bit of re-figuring. How many molds spaced 2" apart and were the distances between the stems and the last molds also spaced-out similarly?

[Greg H]

Oops, well the memory is the first thing to go, I think. http://media5.hypernet.com/~dick/ubb/redface.gif What are you doing up at a quarter till 3 in the morning anyway? But then again, swmbo works on her landscape designs at absurd times of the night. http://media5.hypernet.com/~dick/ubb/wink.gif

Station molds 1-6 were spread an extra 2", the distance betweeen the stems and the first(6)/ last(7) molds didn't change.
---Greg, intending to buy your book

[Todd Bradshaw]

I usually go to bed sometime between 3&4 A.M. I like the peace and quiet when the rest of the world is sleeping. I'll see if I can dummy-up a new profile plan and re-calculate.

[Greg H]

What do you think, will it be worthwhile to do this on a boat this size? It looks cool, and the comments I read about the one in Australia were all positive but your the expert.
Greg

[Todd Bradshaw]

I don't know that I'm an expert on lug rigs, but I have used them, like their simplicity, elegance and traditional nature and have designed and built a fair number of lugsails for people. Since none have come back and their owners seem pleased, I guess that would at least make me a purveyor of tollerable lugsails....

On this boat, there is no question that it would sail fine with a single, standing or balanced lug. It is probably the easiest and least expensive way to put a sailplan that works well on the boat. On the other hand, I really like mizzens, yawl-rigged in particular. Sometimes putting that little sail, too small to generate any real drive, on the stern can be like adding power steering to the tiller. It's ability to fine-tune a sailboat's constantly changing, real-life balance can be so good that certain boats have been able to sail perfectly well with no rudder at all.

My twin, balanced lug rig design concerned me for two reasons. The first was the mast placement, as Howard and I mentioned, which was "iffy" and from my limited testing, seems far from ideal. Secondly, it seemed like two balanced lugs in that small boat didn't leave much room for people.

When I saw Iain's loose-footed, balanced lug main and sprit-boom (or whatever it is) mizzen combo on the Ness Yawl, it struck me as about the classiest looking rig that one could possibly put on that hull. How could anybody build such a lovely boat and not want that exact rig on it? It also gets all of the mizzen sail behind the mast, rather than having part of it intrude into the people-space in the middle of the boat. For the Whilly boat, if your willing to rig it, build it and pay for it, I see no reason that the same basic rig, scaled and balanced to fit the hull shouldn't work and look really great.

I really like Iain' boats but there are things about some of the rigs that bug me. The original, standing lug on the Whilly is one of them. Cosmetically, I'm not fond of the sail's proportions and the raked mast doesn't seem to compliment them and looks to me like it's falling over. There have also been construction details on a few sailplans that I don't consider sound sailmaking practice and I have refused to build the sails for people without correcting them. This isn't all that unusual as most designers aren't sailmakers and concentrate their efforts on the hull and rig plan, not on the cloth. There is enough leeway built into the whole designer/builder/owner/sailmaker system that these things are usually easy to iron-out and everybody walks away happy.

In this case though, the Ness yawl rig looks like a real winner to me and I think it 's adaption to the Whilly Boat should be just as elegant. I still intend to draw out the hull and re-balance things to give you a better idea of how it fits the stretched boat, but I've been swamped with other stuff so it may take a few days. If it was my boat, I'd go for the yawl.