Thread: Lug Rig Heaven Part 2010.1

Originally Posted by keyhavenpotter

Just a small update on setting the sail on the yard and boom at the start of the season. Having tried to set them in the same place as last season, neither were quite correct. Changed them for the weekend sail and boom was too tight and yard too slack. So adjusted them again - we are talking about 1/2" adjustment.

Brian

Brian,

Are the adjustments you're talking about tension between the peak and throat or the head lashed to the yard? I'm assuming if the peak to throat tension is too high there are wrinkles parallel to the yard and if too loose wrinkles perpendicular to the yard when close hauled. Can you judge the correct tension by looking for wrinkles or do you use sail shape as your guide? When lashing the head (between the peak and throat) do you get it as tight as possible or leave some slack?

Thanks,
Brad

Are the adjustments you're talking about tension between the peak and throat or the head lashed to the yard?
Talking about tension when rigged along the yard and along the boom .

I'm assuming if the peak to throat tension is too high there are wrinkles parallel to the yard and if too loose wrinkles perpendicular to the yard when close hauled.
Yes that's correct.

Can you judge the correct tension by looking for wrinkles or do you use sail shape as your guide?

Both. Wrinkles will clearly show too little or too much tension. So you can adjust to that indication. However when it looks ok it could still be improved by the following check. Rig the sail on dry land with downhaul set, and set the boat as if beating to windward, mainsheet tension applied as you would sailing to windward. Now, holding the mainsheet steady, and standing at the back of the boat, luff the boat into the wind just enough to luff the sail. If the sail luff first at the middle of the yard, the peak needs releasing slightly. keep releasing and re-trying the luff until the sail luffs at the throat, the intersection of yard and luff of the sail.

When lashing the head (between the peak and throat) do you get it as tight as possible or leave some slack?

You must leave some slack. This is the key setting on the whole of the lug rig. Here's why. The throat of the sail is tacked to the yard in some way. Either by lashing or shackle the throat clew will move forward as the downhaul is applied. It will pull down some and then stop. At this position the yard tension has to be the tension you want it to be. This is why it is trial and error to achieve a good setting.

I guess it has to be the case that this setting is the setting for one wind strength. Hopefully with good spar bend to sail round the setting will do well enough for a wide range of winds. I tend to have mine set for a nice breeze, which leaves it slightly tight for very light breezes and still fine for strong winds.
Also I find using two bits of string to tie off the clews to the ends of the yards helps. One goes round the sail and yard to take the strain of the wind and the other is used to adjust the clew to spar end, ie the tension we have been talking about. This separates the two functions.

Brian

Brian,

Great explanation. I going to start printing this stuff out for my tuning guide.

Thanks,
Brad

This is Ross Lillistone's video of Phoenix III with lug rig sailing along in light winds.

A great promotion of the lug rig, has to be here on the Lug Rig Heaven thread.

[ame=http://www.youtube.com/watch?v=ga2gI_ZhwnU]YouTube - Light wind[/ame]

Brian

Howdy ... just added a thread specifically about the Goat Island Skiff lug and setting up.

https://www.woodworkforums.com/f169/o...8/#post1174814

Brian, great thread, thank you.

I thought that boat was unmanned-- what a cool trick! Already giving me bad ideas!

Hi all,
On my balanced lug mainsail 8.4 sq m., I have been fiddling with the correct yard bend to match the draft of the sail at the upper part affected by the yard bend and downhaul tension. The yard I have been using was too thin and bendy. I thought carbon sleeves would make it stiff enough with only about 30mm diam., but no, so I added more carbon sleeeves and then it was too heavy and still not stiff enough, so I have just built a new one with greater diameter (50x30mm and tapering to the ends) and stiffness yet is lighter. Lower sail draft is adjusted by an outhaul as the sail is loose-footed. If one wants more strings to pull, there are two more adjustments that can be made. Brian Pearson wrote in this discussion that the correct tension of the head of the sail from throat to peak is critical for max performance. Head tension can be adjusted with a thin line from the halyard attachment to the mast, forward through the eyelet at the throat, back to a little block at the halyard attachment and down and back to the cockpit and a clamcleat. You have to slacken the luff tension with the downhaul before adjusting the head tension. Then if you want to adjust the yard angle and tension in the front part of the sail independently of luff tension by the downhaul, you can add a line as they use on Nigel Irens' Roxanne, see attached pic, to pull the forward end of the yard back and loosen the sail tension diagonally from throat to clew, giving more draft and getting rid of the creases that often form from throat to clew when the luff is not very tight, and peaking up the head a bit. I've tried both in backyard sailing and they work. Sailing is more fun with strings to pull that do something, rather than a simple but "dead" rig. Will give these a real trial next spring as it's down to 8°C this week.
Peter



Hi Peter

There has been a bit of discussion lately about stiff yards, so your own findings have confirmed what some of us have found also.

Looks like they have beads around the yard angle control to facilitate raising the sail without it binding. Interesting...

Just to flip it the other way - the sail on the Harvey's boat was recut when the sailmaker saw the amount of yard bend in the original spars ... and it looks mighty fine in light and moderate breezes. Be interesting to see how it looks with the full quota of downhaul in a strong wind though - whether it flattens enough.

MIK

In the photo it looks rather flat, and has a small crease from the throat which the Roxanne line removes by pulling back the end of the yard. Can it be removed by more downhaul tension? On my sail, no. Probably something to do with how it is shaped in the forward upper third.
Peter

This sail is looks broadseamed to me. Very full up top.
Attachment 150213

Probably close to the limits of my knowledge, but the purpose of broadseaming is to provide depth in the sail where the rounding is compromised.

If you think of the way the rounding works ... you add an amount of rounding in proportion to the width of sail at that same height.

So at the top of the sail there is no width, so the round comes down to zero.

But at the bottom end of the yard you have to add in proportion to the width of sail - but the sail edge has to come in to match the end of the spar. This means that the edge round is not as much as it needs to be in theory.

Same as down the luff - there is no way of adding extra cloth and coming back into the corners.

So the broadseaming isn't needed in the top part of the sail, but becomes necessary from about the bottom quarter of the yard through to the base of the sail.

The top of the sail is not affected much by broadseaming. One way of seeing the broadseaming is to lie the sail flat unattached to any spars - if it lies flat, there isn't much broadseaming. <br>

Also be aware I am working from memory - the diagram might not be quite right - but the broadseaming doesn't go the top of the sail generally.

It is would be theoretically possible to do a completely straight sided sail and put all the draft in by broadseaming. In which point the broadseaming would come back from the luff to the deepest point of the sail camber - in which case it would go to the head.

However if this was the case a small amount of mast bend would put creases in the sail as it pulled the sailcloth hard between the point of maximum mast bend and (usually the clew).

Some rigs tend either one way or the other ... but either way ... the head doesn't have much broadseaming normally.

MIK

In short, it isn't broadseamed then? I've just never seen a lug sail that full up top before.

I must make a sail for my GIS one of these days, just so I can learn something about sailmaking. It's always seemed to be such a dark art to me.

My sailing mentor from my sailing days in South Africa was a guy called Harry Ellens. He was South African born to Dutch immigrant parents and his dad was an architect. All the Ellens brothers were talented sailors, but Harry was the genius. He became a sail maker, learning his craft in England with Bruce Banks. He later joined Elvstrom and then went on his own. But that was when our lives parted and I never did learn any sail making from him. Have always regretted that.

Originally Posted by woodeneye

This sail is looks broadseamed to me. Very full up top.
Attachment 150213

Sorry, Crossed threads, I meant Mark Harvey's boat in the GIS thread. https://www.woodworkforums.com/f169/g...6/index24.html. It looks rather flat, and has the dreaded crease from throat to clew..which I often have, whether or not the sail is flat. I have seen it on many photos of different boats with balanced lug sail. Why do some sails have it and not others? This is what the line from the front end of the yard, around the mast, back through a block and down, prevents and at the same time, seems to make the top front of the sail a bit fuller when you pull the end of the yard back a bit. So now you can have an outhaul, downhaul, vang, head tensioner, and yard adjuster to play with as well as the sheet. But no jib to mess with while tacking!
Peter