What use is a kicker on loose footed mainsail?

[BlueSkyNick]

On a broad reach or run, the kicker (or vang if you prefer) serves a purpose to keep the boom horizontal while the main sheet is freed off at an acute angle.

Pointing high to windward, mainsheet well up the traveller and winched in hard, is keeping the end of the boom down.

On a fixed foot sail the kicker keeps the boom from bending up in the middle, in fact tends to bend it down a bit thus keeping a flat foot.

On a loose footed sail, clew hauled out to set the shape of the foot - kicker has no effect.

Right or wrong? Discuss.

 

[absit_omen]

Good point. Presumably this will apply to all of those (like myself in the past) who have 'loose footed' their main when fitting a lazybag system.

 

[KenMcCulloch]

[ QUOTE ]

On a loose footed sail, clew hauled out to set the shape of the foot - kicker has no effect.

Right or wrong? Discuss.

[/ QUOTE ]
Wrong. If you ease the vang and the mainsheet the boom will rise allowing the sail to twist open and depower. The vang is there to hold the boom down, not to bend the boom (although admittedly that may be a side effect of high vang tension in some instances). Any effect the vang/kicker may have on sail shape through bending the boom is going to be trivial in comparison to the effect of controlling the boom in the vertical.

 

[Pinnacle]

<span style="color:brown"> On a loose footed sail, clew hauled out to set the shape of the foot - kicker has no effect.

Right or wrong? Discuss. </span>


Wrong.

 

[flaming]

Not entirely sure what you're driving at, but basically the kicker will be slack when you're on the wind. Most of the time. Ish.

We only start using the kicker upwind when the breeze is really up, and the main might need to be eased beyond the end of the traveller. But it does change for every boat. On some boats I've sailed the track is very short, and so the kicker is used almost all the time.

 

[snowleopard]

The Laser have a loose footed sail. Have a look at this thread to see how far off beam your analysis is.

 

[Elemental]

Not necessarily true.

As well as applying a downward force (same as the mainsheet) it also applies a horizontal component along the boom. This will tend to bend the mast, thus flattening the main. Take a look at loose footed dinghies such as a Laser and see how this can produce extreme bend even when the mainsheet is loosened slightly.

What effect this has on a yacht mast will be debatable I'm sure.

 

[Judders]

If you have the mainsheet fairly loose, especially if it is fitted to the outboard end of the boom, and then no kicker, the boom can lift just as easilly as it can move outboard. With the kicker tensioned the boom will stay low but can still move outboard.

Not sure I've put that terribly well but I know what I mean.

 

[DJE]

The kicker does the same job on both types of sail; it holds the clew down and controls the leach tension and twist. As you say with the boom close to the centreline the mainsheet takes over much of this job. But by pulling the traveller up to windward you can still use the kicker to control leach tension while using the mainsheet to control the sail's angle of attack.
A mainsail with a bolt rope on the foot should also have lots of spare cloth at the bottom to allow it to take up a curved shape just above the straight boom. It shouldn't be applying any significant upward forces to the boom except at the clew. So the boom shouldn't have any tendency to bend upwards.
I'll let you know what happens when I replace my old bolt-roped sail with the new loose footed one which, with a bit of luck, will be delivered this week. /forums/images/graemlins/smile.gif

 

[flaming]

[ QUOTE ]
The Laser have a loose footed sail. Have a look at this thread to see how far off beam your analysis is.

[/ QUOTE ]

Misleading, Lasers have no traveller, so vang sheeting is the only way forward.
A modern cruiser racer with a good traveller does not have the same limitations, or anything like the same amount of bend on the boom.

 

[maxi77]

[ QUOTE ]
[ QUOTE ]
The Laser have a loose footed sail. Have a look at this thread to see how far off beam your analysis is.

[/ QUOTE ]

Misleading, Lasers have no traveller, so vang sheeting is the only way forward.
A modern cruiser racer with a good traveller does not have the same limitations, or anything like the same amount of bend on the boom.

[/ QUOTE ]

Equally misleading, Lasers do have a traveller though they have less cotrol over where the main sheet block sits, though with the traveller in hard the block can move along the full length but lettin some out makes the traveller take up a triagular shape and thus retricts the mainsheet block travel

 

[Judders]

True to a point but if you take my cruiser racer for example, whilst the track is nearly the width of the cockpit, you still let off more mainsheet than you would if you like. Is it Artemis 3 which has a traveller that runs right along the toe-rail to give the maximum sheeting ability?

 

[snowleopard]

Lasers do have a traveller though of course it is pretty primitive like all its sail controls.

Re-reading the OP, I read it as 'the kicker has no effect on a loose-footed sail'. I see now that it could also be read as 'when close-hauled the kicker has no effect'.

On lightweight racing machines the kicker could be used to bend the boom but on any normal boat with a rigid boom, loose footed or not has no effect on the question.

There are two uses for the kicker when close-hauled: by hauling the kicker tight and moving the traveller to windward (a) the mainsheet load is reduced and (b) the angle of attack of the sail can easily be altered without imparting twist.

My boat has no kicker but the boom is kept horizontal by the mechanics of the rig structure. I am able to have a 2-part sheet controlling a 500 sq foot sail because it needs only move the boom horizontally and has no part in tensioning the leech.

 

[flaming]

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
The Laser have a loose footed sail. Have a look at this thread to see how far off beam your analysis is.

[/ QUOTE ]

Misleading, Lasers have no traveller, so vang sheeting is the only way forward.
A modern cruiser racer with a good traveller does not have the same limitations, or anything like the same amount of bend on the boom.

[/ QUOTE ]

Equally misleading, Lasers do have a traveller though they have less cotrol over where the main sheet block sits, though with the traveller in hard the block can move along the full length but lettin some out makes the traveller take up a triagular shape and thus retricts the mainsheet block travel

[/ QUOTE ]

True, but nothing like the traveller setup on a good cruiser racer.

My point is that tuning tips that work for a lightweight 1 person planing dinghy with an unstayed mast do not necessarily apply to large cruising yachts. One of the functions of hammering on the kicker in a laser is to bend the mast, this is not the case on a yacht. Might work on small sportsboats, but not cruising boats.

 

[bbg]

[ QUOTE ]
On a fixed foot sail the kicker keeps the boom from bending up in the middle, in fact tends to bend it down a bit thus keeping a flat foot.

[/ QUOTE ]

The mainsail on a fixed-foot main does NOT make the boom bend up in the middle. I've never seen it, never heard of it, and one look at a North 3DL sail will show you that there is no significant load at that part of the sail.

The main purpose of the vang is to control the vertical (i.e. up and down) position of the outboard end of the boom - to which the clew is attached. In layman's terms, it controls how hard you are pulling down on the clew (and leech) of the main. It makes no difference whatsoever whether the foot of the sail is attached to boom, or loose footed.

Of course the mainsheet can also do this when the end of the boom is within the limits of the traveller. One could say that the vang is a redundant control when close-hauled (on some boats), but not that it has no effect.

Quite simply, your hypotheses is wrong.

 

[cliffordpope]

[ QUOTE ]
[ QUOTE ]
On a fixed foot sail the kicker keeps the boom from bending up in the middle, in fact tends to bend it down a bit thus keeping a flat foot.

[/ QUOTE ]

The mainsail on a fixed-foot main does NOT make the boom bend up in the middle. I've never seen it, never heard of it, and one look at a North 3DL sail will show you that there is no significant load at that part of the sail.

[/ QUOTE ]

If you attach a spar along one edge of a piece of material, and then stretch the material in the middle, it is bound to put an inward tension on the spar. Whether it actually bends it or not depends on its strength.

Look at the profile of traditional wooden booms. Those for loose-footed sails have to resist compressive forces end to end. Those for laced sails have to resist bending.

 

[flaming]

Non loose footed sails have for ages incorporated a "shelf" of material which was always loose and never exerted downward pressure on the sail.

Loose footed was the obvious next step. So no, the kicker was never pulling on the bottom of the sail.

 

[bbg]

I'm not talking about traditional boats, or gaff-rigged boats. I'm talking about modern sloops.

And in that context, I'll say it again. A fixed-foot main puts no significant upward load on the middle of the boom. Certainly not enough to bend any modern aluminium spar.

 

[saltwater_gypsy]

Some comments:
Your point about upward forces in the middle of the boom is incorrect.The upward force is from the leech of the sail.
Unless you have a bendy boom, the kicker comes into its own on a broad reach and on to running.
On a performance boat you can control the power of the main with the kicker before using the traveller or mainsheet.
On a yacht, creating mast bend with the horizontal force of the kicker is generally bad news and may result in mast failure from the localised load.
If you go on a broad reach and let off the kicker, you will see in a moment "what it is for"!!!

 

[flaming]

[ QUOTE ]

Some comments:
Unless you have a bendy boom, the kicker comes into its own on a broad reach and on to running.
On a performance boat you can control the power of the main with the kicker before using the traveller or mainsheet.
On a yacht, creating mast bend with the horizontal force of the kicker is generally bad news and may result in mast failure from the localised load.
If you go on a broad reach and let off the kicker, you will see in a moment "what it is for"!!!

[/ QUOTE ]

Those comments don't seem to sit with each other, and Whilst I agree with most of them, I strongly disagree with the point about using the kicker before the mainsheet and traveller, as did the North Sails rep we had on the boat at the weekend. The kicker is SLACK upwind, left on its reaching setting, until you are having to ease the main beyond the end of the traveller. And that is purely an inshore short term measure, not something you would tolerate offshore.

I'll sumarise again - the kicker is mainly a Downwind tool to shape the sail once it is beyond the end of the track, it is NOT used upwind in normal conditions.