Thread: Lug Rig Heaven Part 2010.1

Hi Brian,

I am still building my lug rigged PDRacer, and have never heard the term 'kicker', could you please explain to somebody that has never used a lug rig before, what it is ?, and how to "pull on some kicker" ?

I am sure it is just some simple adjustment, most likely I already know about it, just not by the term 'kicker', but obviously it can have a great impact on performance in very light winds, and is therefore definitely worth knowing.

Hi David. Good question. You see most lug rigs do not use a kicking strap at all!

Here's a picture of a kicking strap, or kicker. It fastens to the boom about 18" back from the mast and then at the foot of the mast. Pulling on the line and cleating it off, pulls down on the boom.


It pulls down on the boom because when the wind fills the sail, without any restraint, the sail will bellow out and lift the boom into the air skyward.



This is the whole tutorial on sailing.

Google Image Result for http://www.intersail.co.uk/coachingtips/photos/singlehanded/prepare6.jpg

Here is a picture of my own Scow KS249, and if you look back along the boom from the mast you can see a line from the boom, just below the sail insignia, at an angle heading for the foor of the mast. That is my "kicker"



So why no kicker on MIK's lug and other lugs. It's due to the way the downhaul works. The downhaul is the tackle just back from the front edge of the boom, about 10" back, which tensions the whole sail after hoisting.

If the downhaul is 10" back from the front of the boom, when you tension it, it pulls down on the front edge of the sail but also pulls down on the back edge as well, thus acting like a kicker. Imagine if you move the downhaul back along the boom, the more you move it the more force will be applied to the back edge of the sail.

Conversly if you move it forward to the very front of the boom, all the force will be up the front of the sail and non up the back edge. This is where I was yesterday. My downhaul is at the front of the boom and I had no kicker applied.

OK, why does MIK just have a downhaul and why do I have two controls.

One control is simpler, easier, cheaper and is normal for lugs.

My two controls, for racing, split the function of the single downhaul into two separate controls which gives me more control of the sail and leach tension. But as you can see, more head scratching!

The other reason I will always use a kicker is when sailing downwind. With the sail let out, the mainsheet does not exert any downward control on the boom, just the dowhaul. But the wind is pushing the sail hard and will lift the boom with only a downhaul in place. As the boom lifts the sail bellows forward and creates an opportunity to loose control of the boat, particularly when sailing in strong wind and waves which are rolling the boat. For me it's a safety thing to prevent this by using a kicker to stop the boom lifting.

Hope that helps, but please ask if I have not explained myself clearly.

Brian

In the tutural you link; the device the young woman is adjusting at the boom, we in the USA would call it a boom vang. For traditional rigged boats like the Goat Island Skiff calling it a kicker sounds so much better.

Hi Brian,

Thank you very much for that great explanation, my 34" long, plywood 'scratch built' ( made by following a basic a set of plans ) Radio Control Model Yacht, which has a simple roughly triangular mainsail and jib ( similar to most modern type yachts ), also has a simplified version of this boom tensioning system, as it is not a lug rig I didn't connect the idea ( I was also unaware of the actual name for this tensioning adjustment ).

Both sails have a boom and tensioner which is manually pre-set, setting the tension too tight restricts the boom rotation and the efficiency of the sail to provide propulsion, but also pushes the boom outwards from the centreline of the deck, which can be useful in light wind conditions if you also reduce the sail foot tension to compensate.

From experience sailing my radio control model ( which has a single electric winch to control the sheets, one for each sail, which combine to be controlled as one, and full rudder control ), which allows it to be sailed on almost any heading relative to the wind, the boom tensioners ( kickers ) are most useful in downwind sailing, allowing the sails to retain maximum efficiency in providing propulsion.

The attachment point of the sheet, relative to the boom pivot point, on each boom allows the jib to be hauled in tighter than the mainsail at any point ( this helps to catch any light breezes more easily, especialy while tacking ), this is the same sort of relationship to the amount of force the kicker position affects the leveling of the boom ( relative to a flat deck ), when sailing down wind.

As with most things under specific circumstances, there are advantages for both lug rig systems, your lug rig appears to be acting more like just having the mainsail only, on my radio control model yacht, thus needing the extra boom/sail tensioning control, as opposed to Mik's ballanced lug rig, which allows one sail to act similarly to having both the mainsail and jib, while also keeping the boom relativly level under different wind strengths with just the downhaul.

Often in the states, when comparing standing vs balance lugs, the term 'self-vanging' is invoked to describe the way the downhaul on the balance lug will tension the luff and the leach a little. SO the boom doesn't go sky high when you are running. I got into a scary situation in a high aspect carbon rig standing lug when the yard was forward of the mast and we started rolling!! I saw why probably seconds before we might have gone over. It is s safety thing.

Great discussion Brian.

The general rules for very light winds are that the sail is flat and well twisted.

With the crinkling in the foot and head (through them needing to be tensioned a bit more) it might be allowing the draft to move well back and give you a finer entry with less of a sudden curve.

But that would be guessing! I am sure the Netherlands Goat sailors will be reading this with some interest.

MIK

Originally Posted by Boatmik

I am sure the Netherlands Goat sailors will be reading this with some interest.

MIK

Confirmed!

We're reading in Maine too!

My son bought me a waterproof headcam for Christmas so if I can manage to find out how to work it there might be some video action soon. It's our Easter Regatta next weekend and weather is usually either blowing and cold, or soft winds and warm, don't know which yet.

Might try some sail setting stuff off the water as a first trial.

Brian

Sometimes nice things happen.

Last summer we had all sailed in to the beach after a race and I was collecting my trolley when a nice chap asked me about Scows, and Keyhaven Scows. We had a good chat and I mentioned Ken, who builds the Keyhaven Scows, had a set of mouldings for sale and why not have a chat with Ken.

Yesterday, out having a bike ride and popped down to Keyhaven to see if anything was going on. Not much, very cold 20 knot breeze, so sat having a chat with a pal, when this lovely brand new green decked, white hulled Keyhaven Scow rolled by after coming in from a sail. It had been the only boat out.

Went to have a nosey and low and behold it was that same nice man I had spoken to last summer and he had bought that set of mouldings and was just collecting the completed boat from Ken. The sail was it's maiden sail.

We had a really nice chat, and it was great to be there to round off the story. Cliff, even had pictures of my rigging from the internet he had found without realising they were my pictures and best of all he took a nice picture of my Scow sailing in from racing last summer.

Here it is,



Look really closely at the leading edge of the sail. Those tell tales help hugely in tuning the sail. If you can get all three streaming at once you have cracked it!

Note my top telltale is not streaming. never have quite managed a really good set with this sail on these spars. The sail was cut for different spars.

As I have mentioned before, we use kickers ( vangs) on the Scows and the top tell tell indicates correct vang tension. You can make it stream or stall just with the vang/kicker.

Getting the air to stream efficiently over the top third of the sail is key to racing performance. The critical sail setting is the way you tie the head of the sail to the yard. You have to set it so that when all the tension is pulled on the downhaul the head of the sail is tensioned just right. Too much tension on the yard will stall all the upper third of the sail. Too little does not work either.

We usually leave the peak tied off with an inch or two of slack. The downhaul then pulls hard down the leading edge of the sail. The throat clew is tacked to the front of the yard and that fixing stops all the tension carrying on up the yard. You want just enough to tension the yard correctly. This is hard to write and I hope it makes some sense. You tie the throat clew to the front of the yard, but as the downhaul pulls hard on that it moves the clew a little further down the yard, and this movement creates tension in the yard of the sail between the throat and the peak.

How can you tell when it's correct. Rig the sail on dry land and position the boat on the wind. Move the stern of the boat to luff the sail and watch carefully where the sail luffs first. If it luffs high at the yard, then slacken the rope tying the peak to the end of the yard a little. Try again. Keep easing it until the sail luffs at the corner intersection of the yard and luff. That is at the throat of the sail.

When the sail luffs at this point the whole sail is working at it's best and upwind performance is much improved.

Brian

Hi Brian

Thanks so much for this information, which is clearly based on your extensive experience with the balanced lug! Now that I have finished construction of my GIS, I am fast approaching the day when I can rig my boat, so this is the sort of detail that is so much appreciated.

Brian,
Great explanation from your posts on this thread - now have a much better understanding of how to trim the balanced lug (which I have't considered as a possible rig because of it's oft questioned windward ability).

You mentioned using carbon spars... would you please say more about them.

Would c/f windsurfer spars be useful as the source for such tubes?

PS - do you have any data such as the angles on the compass between tacks when going upwind that can be reliably acheived?

Originally Posted by tommyboy

the balanced lug (which I have't considered as a possible rig because of it's oft questioned windward ability).

You mentioned using carbon spars... would you please say more about them.

Would c/f windsurfer spars be useful as the source for such tubes?

PS - do you have any data such as the angles on the compass between tacks when going upwind that can be reliably acheived?

Windward ability. A friend bought a Gull Spirit, Proctor designed modern alloy rig with main and jib. A smaller version of the Wayfarer. When we sailed together I could sail just as high as he could.

Against high performance dinghies she does sail lower, but not by a huge amount.

The rig has great benefits as well. I was just giving up windsurfing when I took up dinghy sailing again in the Scow. You know that feeling of windsurfing along on a reach, everything in balance. Well my first ever sail with a balanced lug rig gave me just the same feeling - going slower of course. It's possible with the balanced lug rig to sail very a completely neutral helm on all points of sail. It's a great feeling - sailing along and the tiller extension metal joint just rattles slightly - no load on it at all - the boat completely balanced.

My previous Scow was so well balanced I could make the helm neutral on any point of sail just by correct sail adjustment and moving my weight to make the helm neutral.

Carbon Spars.

Scows used to have wooden spars, rather undersize for racing and the loads that new control systems apply. So they went to alloy spars some years ago. I need a set for my fit out and found a set of carbon tubes were much cheaper than the racing alloy set. They are very light and have performed very well. They are completely sealed so give much better floatation than ally spars with holes in. The mast and boom are 50mm. The yard is 40mm tapering to 20mm. They are 50% glass 50% carbon and have 1.4mm section. You would want something a bit stiffer and sturdier for a Goat, especially the free standing mast.

Winsurfing spars.

When John Claridge began building Scows he bought about 100 windsurfing alloy masts that were made by a leading spar maker but were useless as windsurfing masts. he used the top 3m for the yard and the bottom 3m as a boom. Then bought 50mm straight tube for the mast. My black Scow has just those old spars and my sail set wonderfully on them.



So that confirms windsurfing masts can be used for the yard and boom for a sail of about 65 sq ft - but Goat's is a fair bit bigger - 105sq ft. I have two windsurfing mast in the garage but have not had the heart to cut them up!

Tacking angles. With a well set sail, good foils and a balanced helm there is really nothing to worry about. The performance is good. I have a compass but race in such strong tidal waters that each tack is strongly affected by tides. I will see if I can work something out.

Brian

Brian,
Thanks for the very careful reply.

Helps a lot, now will start shopping for a used 2" (50mm) carbon windsurfer mast and see what wall thickness they are.

Would be great to see some actual tacking angles for this type rig.

As you seem to realize, there are lots of variables, but you seem to have worked hard at getting the rigging right so maybe your data will help me and others to discover the potential of this rig.

Many thanks,