Controlling sail twist on any boat is critical for performance. Here we describe two methods for getting more performance all round and safer handling downwind – add to this that it doesn’t need to cost even a cent by using all your existing gear.
The Overview
On other pages in this website you can see the simpler way we set up the lug rigs on our performance boats. In general the boats are a reasonably close match for modern boats with modern rigs. There is not a huge difference in performance between conventional boats and well set up balance lugs.
The path to increased performance really has been a long process – about 120 years if you look at sailing canoes, which in many ways brought a lot of modern thinking and gear into existence in the late 1800s.
This was fundamental improvement in foils (centreboards, keels and rudders) and sail interaction with spars to automatically shed excess power in gusts and regain the power automatically after the gust passes.
Then to sail controls where the most significant stride has been in controlling sail twist.
Most of this was very well understood for modern rigs by the mid to late ’70s and was achieved cheaply using timber, standard aluminium alloys and rope.
Since the 1970s there has been little innovation in boat setup or our thinking about the component design, but instead of an improvement in understanding the fundamentals most of what passes for “innovation” has been a shift to more expensive materials and items.
The first time the boom vang (or kicker) that controls sail twist was used in the International 14 class the boat that used it ran away with the race – we are talking about 5 or 10 percent increase in performance … not the half a percent from spending large amounts of money on carbon.
So point is .. that real innovation doesn’t cost much to apply and should be applicable to most types of sailing rig
RELATED LINK – All our Lug Rig Articles – over 20 directly useful articles on setting up and thinking about lug rigs.
The real advantage of modern rigs is shared information and testing in competition.
The advantage is the opposite of what you see on recreational boat forums. The discussion on any point goes around and around. It might seem resolved and then it will reappear again. Is a fresh painted surface less drag than a sanded bottom?
A great example are hydrofoil sailboats. They have a long history from about 1915 with little improvement in speeds even up through to the 1980s with Russell Long’s speed record machine. It could sail upwind and down, a beginner could tack and gybe it easily. It was a high point. But the real jump in development was when the Moths started using foils. We saw the first boats struggling to take off in 8 or 9 knots of breeze, falling off the foils when tacking. But quickly in the next seasons, the brilliant community of home boat developers found ways of making sure the Moths could become airborne in 7 knots of wind, then 6. The current state of the art is if you can get the boat up then it will continue to foil in under 2 knots of wind – conditions most people (except for experienced sailors) would say “there’s no wind today”.
Monitor 1940 – 20+ knots, couldn’t tack – needed lots of wind to lift off – sails a few times with small improvements
Icarus – mid 70s – speed range 23 to 28 knots – not able to sail efficiently in all directions, can’t tack efficiently – sails once a year for a week.
Moth – Mid 90s – full range performance in all directions – an 11ft boat that is faster than most catamarans around a racecourse, tack and gybe easily.
Here is a graph of Moth Performance against other boats (which have changed performance little) over the years. The recent steep part of the graph is because of the rapid hydrofoil development.
That’s the advantage of racing classes is that they have … racing. And real improvements get tested by hundreds of thousands of boats every weekend. They publish information (now on the net) but formerly in newsletters as the current champions would share their knowledge. It is well known that if a group decides to share their knowledge effectively they can become a real force on the world stage.
The Goat Island Skiff group, in particular were aware of the tendency to lose information so we started to share information and also to make sure it was written down. One of the resources is the Lug Rig setup and tuning WIKI. Another are the growing number of meetings of goat sailors, here at the Small Reach Regatta last year.
We have recorded different spar weights for different construction and timbers and also the basic bend characteristics of the yard and boom.
This enabled us to identify a trend that people were making the yards somewhat stiffer and the booms very much so – particularly as they saw the advantage in a loose foot setup.
If information is recorded and shared trends like this start to appear. And there is a ready menu of information for any builders who want to be at the pointy end of development to make the lug rig faster, easier to handle, faster when reefed and maybe faster to rig as well.
In other words we have used the racer’s own trick as well as we can. The internet means you don’t need a big number of boats in one location, though there are enough Goat Island Skiffs to meet in twos and threes reasonably regularly.
Previous Goat Island Skiff setup, Downhaul and low stretch ropes
Rigging setup for Goat Is
Goat Island Skiff standard setup
Most lug rig boats are set up with a number of easily corrected deficiencies. That page has the correct methods to rectify them one by one.
The most important items are
First Assumption – a low stretch halyard
There’s no point in optimising any settings on the rig if the halyard just stretches when downhaul, sheet or wind pressure is applied.
We generally use a 4 or 5mm polyester line with a spectra or dyneema low stretch core. Thicker lines can have “geometric stretch” because there is not enough tension to pull the threads that make up the line as straight as possible and close all the air voids in a relaxed rope.
A note on the Dixon Kemp single line with no fittings or loops that may bind.
This DOESN”T mean you can ignore the other items and the halyard system shown on the page (from the Dixon Kemp Manual of Seamanship – 1850 something) is one of the very best systems for small boats. Bolger had lots of nice words about the balance lug rig but had four criticisms. This halyard system eliminates all four making it an excellent rig choice.
You only need rope – no special fittings. It is tight and holds the yard close to the mast when it needs to be and loose when it needs to be. It can’t bind or jam and the yard is lowered and raised horizontally unlike systems where the halyard is attached to the front of the yard allowing the peak to drop below the halyard attachment point and come down peak first.
The single most important rope for Lug Rig Performance is a correctly adjusted Downhaul
The Downhaul on a balance lug is responsible for tensioning the both the luff and leach (front and back edges of the sail) . Leach tension controls the twist of the sail. Before Bermudan rigs started to be scientifically developed in the second decade of the 1900s the lug rig was the predominant small boat racing rig – because it has twist control.
Basically the history of major performance improvements in sailing have been about the control of twist. The nice thing about the balance lug is that it controls twist without any extra gear. The downhaul does need to be powerful.
A secondary effect is to keep the boom close to the mast. On the size of boats we sail a 50mm gap because of wind pressure between boom and mast is one degree of pointing angle. One degree might not sound like much, but wait until some guy sails away from you :).
We are typically using pulley systems or pulleys backed up with a truckers hitch to give these mechanical advantages. A rough guideline
1/ Beth sailing canoe – 67 square feet mainsail – 2:1 pulley system backed up with a truckers hitch – maybe about 5:1 after accounting for frictional losses
2/ OzRacer – a very stable boat can carry 89 sq ft. Similar to BETH
3/ Goat Island Skiff – 105 square feet – 6:1 or 8:1 using pulleys. This is much less than the 12 to 1 or 16 to 1 used in the boom vangs (kicker) in conventional boats. More about that later.
How much tension in a Lug Rig Downhaul? Much, Much more than most think!
We have found that the downhaul on a Balance Lug or other Lug sails needs to be adjusted for changes in wind strength and boat speed.
1/ Light winds – boat is not moving reliably – the downhaul can be slackish – this allows the sail to twist which helps the boat accelerate and accommodates for the wind shear effect from the combination of apparent wind and the wind gradient (wind is stronger higher up because it is further away from the ground). The point where you start to put in significant tension is when the boat is moving reliably.
2/ Light and moderate winds where boatspeed is consistent – downhaul should be very firm. Pull the downhaul while pushing the boom down for most setups.
3/ When the boat is overpowered in the lulls be BRUTAL with the downhaul. It must be brutally tight.
So that’s where we were about 12 years ago.
And then along came Brian Pearson.
The Lesson of the Lymington Scow – a century of Lug Rig development.
Brian rolled up on my forum because he could see we were being serious about improving the efficiency and performance of the balance lug rig – a kindred spirit. He races (among other things) in the Lymington Scow class which is rigged with a Balance lug mainsail. Some boats are raced singlehanded with mainsail only and others are sloop rigged.
It is an excellent low cost class and provides very tight racing because the speed differences between boats are restricted by length.
I was completely unaware of them but when Brian mentioned they were built by John Claridge (several times world champion as well as builder and designer in the ultra competitive Moth class)
Remember what I said about boats improving fast when there is regular racing … well … the scow has been a racing class since 1905. And Brian has been one of the sailors with runs on the board.
They have learned a thing or two.
Remember I said that modern boats have powerful boom vangs/kickers?
Well, the Lymington Scows do too.
They have a setup that was quickly fitted to this Goat Island Skiff. The pivot point of the boom is just to the left side of the mast. The system here with the attachment points behind and in front of the mast introduces a fair bit of unnecessary stress.
The sailors that used it found it effective and powerful. It also allowed some interesting (some would say strange options) of moving the boom backwards and forwards relative to the mast for steering balance upwind (a couple of degrees of weather helm in the tiller please) and on a run downwind the sail could be centred with more equal areas either side of the mast
Sail forward in downwind position
Sail back in upwind position
I was lucky enough to go sailing on Bruce’s (woodeneye on my forum) Goat one the central Coast of NSW. Powerful, but I didn’t like the expense of two vang systems and also I thought it was too finicky for average sailors. If you wanted to reduce the tension in the after vang you had to take up some of the slack in the forward vang. Also it was easy to lose where the boom should actually be because it is all floating around – to confusing except for the experts and frustrating for some would be experts (me).
The Lymington scow avoids some of this complication as the boom is carried with the forward end adjacent the mast – see the photo of a section of their fleet up the page.
It was also getting away from the simplicity of the Goat Island Skiff. The boat in standard form has a total of 5 or 6 blocks (pulleys) and it is a fast boat without all the stuff. So was there a way to get the same effect with something like the original gear?
The original gear can do this … at the Small reach regatta and more complex gear doesn’t change this much.
Video image can take a moment to load.
Enter the Vanghaul and Bleater (it is a GOAT) – a gentleperson’s approach to Balance Lug efficiency
So the criteria have changed or become better defined.
1/ We want to control twist better
2/ It can’t be more complicated than the standard system
3/ It can’t be much more expensive than the standard system
One of the other changes of the previous year or two contributed. Many builders had decided to change over to a loose footed mainsail and get rid of the lacing along the foot. This is very good for sail power, but the result is that the existing downhaul and the square lashing used to hold the boom against the mast can easily slip forward or back if not fully tensioned.
The double vang photos above show a loose footed sail … no lacing along the boom so you can adjust the sail depth more easily.
Need a stiff boom to control Sail Twist with a vang on a lug rig
The other change that had led to was experimentation in the boom stiffness and dimensions as the standard boom in the plans only works with a laced foot – this is a snapshot – you can see the complete data on the WIKI
Stopping the Lug Boom Moving forward under vang/kicker loads
.In a couple of days discussion on the Goat Island Skiff forum we worked out a new combination.
This is the old way – the square lashing
It’s main function was to keep the boom close to the mast. Every 50mm gap is a degree of pointing, plus gusts make the gap bigger.
Roll on the Preventer or Bleater
One of the sailors was having a small problem when rigging – the boom would swing forward and get caught under the gunwale. The original square lashing wasn’t cutting it – particularly when a loose foot arrangement was used on the boom. The square lashing …
So he had tied a rope to the front end of the boom and then to the mast. We decided to call it a bleater … well, they are Goats. I’ve seen it set up that way before. The middle one is a direct corollary of the halyard system we use but not adjustable.
This illustration below shows the original square lashing compared with the bleeter (bleater)
The “strong version” is what we settled with. It reliably prevents the boom moving forward or backward and also closes the gap between boom and mast.
On our racing geese we use the “strong” version.
Enter the “Vang-haul” – moving the downhaul back along the boom to act as a sail kicker
So here we introduce the vanghaul – a mixture of boom vang /kickerand downhaul which works nicely in conjunction with the bleeter.
The really exciting thing to me is it is EXACTLY the same setup as the original but with the rope and downhaul redeployed. A really nice solution.
So to explain the development.
First a powerful downhaul
Starting point for the new arrangement were loose footed mainsails on stiffer booms making it difficult to prevent the boom slipping forward.
Information from Brian Pearson changed our thinking.
Finally using the same parts we engineered a more workable solution for the majority of sailors.
Compare Two vang method with the vanghaul with Bleeter/Preventer.
Then the comparison of the original, the two vang and the bleeter/vanghaul system in this diagram
Top diagram – Original Boom to mast connection – green square lashing
1/ Top section was the original system in the plan and the general lug setup for all the storerboats. The Square Lashing is simple and effective.
Some have said it is not necessary to have an attachment at all and let the boom move away from the mast.
Unfortunately this reduces the pointing angle (about 2 degrees) and sets up a poor gust response dynamic as the front of the boom moves to leeward in each gust. Around the same loss 2.5 deg in performance terms
Losing 2.5 percent of performance because of a dollar’s worth of rope?
2/ Mid Diagram – the two vang system – too fiddly for normal sailing.
But can be OK on an expedition when you set up the rig for a whole day downwind.
The two vang system from the “Boy Racers” will still really like this system with it’s infinite adjustment and ability to throw the rig around relative to the mast. It allows the widest range of options but at the risk of some complication, a little extra expense and also a need for the knowhow to feel what the boat is doing and to put the sail in the place you want.
3/ Bottom Drawing – the bleeter/preventer takes care of forward thrust and the vang effect of downhaul controls twist
Bleeter/Preventer (green) with Vanghaul (purple).
This is what we are using on the Goose Fleet. Not only is it super cheap – every thing can be done with knots – but the bleeter/preventer doesn’t need to be touched with changes to downhaul tension.
Don’t overdo bringing the Vanghaul back – not be the angle of a conventional sailing dinghy vang/kicker
One important note is that the power of the vanging is proportional to the distance between the tack of the sail (forward bottom corner) and the vanghaul. So the comparison with the conventional rig is shown.
Don’t compare angle of the vang as you would with a normal sailing dinghy.
Compare the distance from the tack. The distances should be about the same from the tack of the sail … not the distance from the mast as we were tempted to think.
If you have the vanghaul too far back from the mast you lose luff tension in the sail, very bad for pointing upwind. So for Goat sized boats we have found the vanghaul should be attached to the boom about 4 or maybe 6 inches (100 to 150mm) behind the mast as a starting point. Dinghy size boats anyhow.
Sailing is the final test for the correct position of course.
As I said, not everyone likes it, but some certainly do. And it uses the existing gear and means that you have a good excuse to update a puny downhaul.
More Lug Information
Our Boat Plans Include Several Balance lugs
