Loose footed main sails

[delmarrey]

Thanks for the link Gord! Some good info there!

It seems the only advantage to a boom tracked main would be if one wanted to add a shelf. And even a pull string (foot cunningham) would work as well just like on a genoa. That's if the mainsheet is attached to the end of the boom. If in the middle then a tracked foot would be necessary.

[Alan Wheeler]

Soooo?? with a lose footed sail, how does a vang work. I don't see a way of depowering the sail. OR am I missing something

[GordMay]

On a run or broad reach, when the mainsheet traveler has been eased all the way out, further easing of the mainsheet causes the boom to rise, and puts a twist in the sail. If you trim the twisted sail to prevent the upper portion from luffing, it will be over-trimmed at the base, resulting in excess weather helm. A vang avoids this by pulling the boom down to straighten the leech and put the tack) and clew of the sail more nearly in the same plane. This, in turn, reduces the amount of rudder correction needed, and improves boat speed. When sailing downwind, vanging the boom parallel to the water's surface also limits the effect of forces pushing the top of the mast to weather, causing uncomfortable rolling or, at worst, a sudden broach. On a beat, a vang can be used to prevent the boom from rising whenever the mainsheet is eased for a puff of wind.
The vange works on the boom, whether the mainsail is loose footed or shelved.

[Rick]

You will wish that you had the ability to tie your reef lines quickly and neat on the sail foot NOT around the boom, which you have to do with a foot rope.

The first time that I got hit by a squall (which happens all of the time in or near a convergence zone) I couldn't get all of my reef lines tied before the reefed sail began to fill with water, an I'm telling you that it scared me with the boom out and all of that weight accumulating out there making the boat roll more.

After that time I ALWAYS tied all of the reef lines so that no water could run off of the sail and pool in the bottom....it is DANGEROUS!

My present sail is fully battened and not loose footed yet I am NOT going cruising without converting it so that I can more quickly and easily tie the reef lines.

BTW: Brion Toss, of Brion Toss Rigging also recommends NOT having to tie reef lines around the boom.

Note his website at briontoss.com

Regards,
Rick

[Curtis]

Alan Wheeler once whispered in the wind:
Soooo?? with a lose footed sail, how does a vang work. I don't see a way of depowering the sail. OR am I missing something

The vang works in both cases by controlling leech tension to open or close the leech. Boom down closes....boom up opens. the foot configuration doesn't really matter as long as the clew is attached to the boom.

[Wahoo Sails]

Virtually all of the sails I make currently, are loose footed. I utilize a "super slug" under the clew, and a foot cord to eliminate flutter. Since I do not do "racing" sails, the vast majority of my sails are hollw roached, without battens or headboards ... and my customers love them. Next on my slate is a mizzensail for a pearson 36 ... loose footed, hollow roached, battenless with a single reef and setup to work on a Dutchman flaking system.

L S/V Evaluna
Bob

[Alan Wheeler]

Thanks Gord, but what I was infferring, was the control of the Bend in the Boom. Close hauled in heavey air (with main sheet connected to end of boom) the centre of the boom bends upwards, allowing for the sail to take a fuller shape. (Just the same as allowing the cunninham to ease in lighter air). Thus more power when you don't need it. The vang system allows you to straighten or even apply a bend in the oposite direction, thus pulling out that shape and de-powering the sail in the heavier air.(just the same as tightening the cunnigham). The vang tension is in a different direction to the cunningham. The cunningham tensions the extreme foot of the sail. But has little ability at shapeing the mid section of the sail. The Vang allows ou to shape the mid section of the sail.
Soooo, if the foot is not attached to the boom, the bending of the boom will have no control of the shape of the sail, hence my question.
Hope that made sense.

[GordMay]

MY BASIC MAINSAIL TRIMMING PROCEDURE:
My racing experience is limited and from long ago, so the following likely contains errors. Anyone who has ever met a layer is specifically prohibited from using this information, in any manner whatsoever.

The main sail helps to steer the boat by functioning like a trim tab on the keel.
The leech, has an important influence on the directional tendency of the boat. A closed leech directs the airflow to windward, creating a large side force to leeward at the stern of your boat. This creates weather helm and tends to push the bow of the boat to windward.
Similarly, an open leech allows the air to flow easily off the mainsail without developing as much sideways force This will result in less windward helm.

1.Set twist with mainsheet tension.
On a mainsail, twist is controlled by the amount of mainsheet tension, as well as the amount of tension on the vang. The mainsail leech is the best indicator of how much the sail is twisted. To set the proper sail twist, trim the mainsheet until the top batten is parallel to the boom.
When the sheet is eased, the main has a very twisted shape, with the top batten falling off to leeward . As you trim the sheet, the top batten angle narrows until it is parallel with the boom. Trimming harder will take away all the twist and close the upper leech.

The best average setting for the top batten is parallel to the boom. With the top batten in this position, the top batten telltale should stream aft between 50 and 90% of the time. This tell tale, attached to the aft end of the top batten and extending 8 to10 inches beyond the leech, indicates whether the upper leech is stalling. When the leech is stalled, the telltale curls around to leeward of the main. Twisting the main sail more will open up the leech and re-establish the airflow. In choppy conditions, after tacks and in light airs, ease the sheet to open up the leech slightly and prevent stall.
The primary means for adjusting depth in the upper two-thirds of the main is mast bend. Bending the mast moves the luff away from the leech, which does several things simultaneously - it flattens the sail, opens the leech and moves the draft aft. If you see overbend wrinkles, ease the backstay tension or tighten the checkstays/runners to straighten the mast.

2.Outhaul
The best way to control depth in the lower third of the main is with the outhaul. The tighter the outhaul, the flatter the bottom of the sail. If the waves are big for the wind, ease the outhaul slightly to give more power. If the waves are small for the wind, as in an offshore breeze, pull on the outhaul to flatten the sail and reduce drag.
Besides depth, the outhaul also changes the tightness of the lower leech. Easing the outhaul adds depth to the foot of the main. Conversely, tightening the outhaul opens the lower leech.
The tighter the lower leech, the more windward helm you have. That's why it makes sense to tension the outhaul in heavy air to open the leech and reduce the helm forces.

3.Set draft position with luff tension:
Once you've set the overall depth of the sail, the next step is to position the area of maximum draft - at about 50% (centreline ‘twixt luff & leach). This is usually done with the cunningham tension.
The cunningham applies tension to the luff of the main, and this controls draft position. Tighten the cunningham to move the draft forward; ease it to let the draft move aft. In general, the more you bend the mast, the tighter you need to pull the cunningham to get the draft in the right place. You'll also have to pull the cunningham harder on an older main, because a sail's draft moves aft with age.
In light airs, keep the cunningham quite loose. In light airs, lower the main halyard (especially downwind) to get the proper luff tension.

4.Set helm balance with traveller position:
The main sheet traveller controls the angle of the mainsail to the boat's centreline and to the wind This has a large effect on helm. 3 to 5 degrees of windward helm is the ideal setting.

5.Fine-tune the total power of the main with the above controls:
The final step in mainsail trim is continual evaluation of the sail's power. The main trimmer must keep track of the boat's heel angle, speed and pointing ability.
The most obvious indication of over-powering is the angle of boat heel. Boatspeed and the amount of windward helm are actually more sensitive and accurate indicators of over powering.

Measure the rudder angle required to sail in a straight line. The ideal angle is about 3 to 5 degrees of windward helm. If you have more than this, you are overpowered.
Depower the mainsail by bending the mast, opening the leech, easing the sheet, dumping the traveller, and reefing if necessary. These adjustments are simply changing the total power being exerted by the mainsail. Since most of the main's power is side force, adjusting the amount of this power affects windward helm. Ideally you should reduce windward helm down into the acceptable range.

***E. & O. E.***

[jim lee]

Pulling the bend outta' the boom..

Mast bend I use all the time. I've never seen a bendy boom. From my understanding when you pull down on the boom your pulling down -only- on the rear/leech/grommit of the sail. NOT the middle of the sail. In fact, when I pull my mainsheet/vang a lot, it seems to deepen the main not flatten it. Bending the mast and streaching out the foot (outhaul), flattens it.

The bit about catching water in the reefed main completly lost me. I know at one point I caught a fish in mine. Stinky when we found it pulling into Hilo days later. Yeech!

But then, there's a lot of different sail controls out there.

-jim lee

[Alan Wheeler]

Thanks again Gord. Great article you wrote in your reply. I am certainly at the crawling stage when it comes to all this stuff. The comment I made was because of an article I recently read, describing what vangs did. As I am fitting my yacht out for sailing for the first time, I was unsure what advantages/differences between a conventional vang and a rigid vang system would give me. So I found many articles on the web and read them. One mentioned the comment I made above. So either I mis-understood what was writen, or it was incorrect.
Still, I wouldn't have had that great piece of info you replied, if I hadn't have have said anything.
I made and fitted a very nice rigid vang system, one of which I was most pleased with my efforts. It works just great and saved a heap of money.

[GordMay]

Wheels:
I’m pleased that you found the dialogue helpful.
I’ve never been much of a sail trim expert, and haven’t even sailed for several years now.
I’d highly recommend that you (everyone) follow the Expert Forum at ‘SailboatOwners’ - and perhaps post your comments & questions for response from a true sail expert.
http://www.sailboatowners.com/forums...ew.tpl?fno=443
Gord

[Jack Tar]

The loose footed main has its place but its not on a bog boat. All the forces exerted on the sail are transmited somewhere. On a main in a track it is transmited to and through all the cars or trac slides. On a loose foot more of it is transmitted to the main sheet and attachment point (single). So yes I agree the sail may strech and loose its shape faster because more forces are exerted on one specific area or the sail rather than being spread along the boom and mast .

[Jon D]

Jack

Don't think your statement on loads is correct. It's been a very long time time since I owned a racer or cruiser with a footed main [about 10 years]. The loads are never on the slides on the foot though.

I remember them just laying failly loose unless the outhaul as pulled very tightly. All the did was break from slatting or etc.

What sailmakers have learned is that attaching the foot does not buy you anything. If attachng the foot transimitted extra drive beleive me every race boat would have a main attached at the foot.

Also a loose footed main when cruising makes it much easier to tie reef in along the sail as it 'bunches' better.

[Jack Tar]

If you dont think any load is transmited from the sail along the boom why do the slugs either fail, wear or are torn loose in high wind . They will pull of like a row of buttons . With a loose foot all the force is focused on the aft eye or halyard/sheet attachmnet gromet in the sail . Thats why with a boom you get lifting of the sail and to counter same is an even, well almost even distribution of that same force along the boom .

[delmarrey]

So what would you consider, too big a boat, for a loose footed sail?

And as for having slugs on the foot, I don't think I've seen too many of those. As you described, probably a good reason not to have slugs at the foot. Only boltropes into the boom, in this territory.

The advantages I see to a loose foot are the trimming capabilities like flattening or extra loose for downwind. As for the clew taking all the stress it seems a main "built" for a loose foot would be much like a genoa with exception of the luff being straight up vs. angled back.

And one thing that really opened my eyes was about the rain not filling the shelf while reefing. I've had that happen here in Rain City and it wasn't fun. Especially, when I hoisted'r back up

I'm needing a new main pretty soon and would like the best for performance and ease of handling. And I'll be weighing the comments here for that decision. I don't trust the sailmaker; I'd rather hear it from the experienced.