Topping lift or boom kick/solid

[Quoddy]

What are the advantages and disadvantages of the two methods as far as trim control?
Let’s say we are on a broad reach and get hit by a big gust. It would seem that after the vang is released the limited travel up of the boom kicker/solid vang would not allow as much easing of the leech.

 

[Bill1565]

Your solid vang should be adjusted to give you plenty of twist when released. But that would not be the first line I would reach for in a gust. You should ease the traveler if you have one or the sheet if you do not. You should also also head up into the puff.

 

[Paul J. Rusyniak]

Over and above what Bill said about which lines to reach for first, our Hall QuikVang does not present the problem of limited upward travel of the boom.

Perhaps I'm reading your question improperly (It wouldn't be the first time!)?

 

[Rick Sylvester]

On a broad reach

I'd be reaching for the mainsheet first. Although the traveler might get the job done, when we're reaching the traveler is usually all the way down anyway and the boom's vertical component is then controlled by the vang.

As the others have noted, the limits in either direction for a solid vang will depend completely on how much travel it has and where you attach it to the boom. If you need much more than a foot or two of lift on the boom I'd suggest it's probably time to reef.

 

[RichH]

A contrarian viewpoint of 'twisting' instead of flattening/'blading-out'/reefing.

The topping lift really has no trim control effect, other than in very light air when its used to balance/counteract the *weight* of the boom + sails. In essence, the topping lift is only there to prevent the boom from dropping into the cockpit when the mainsail is dropped/furled.

In heavy air, without vang or rigid vang control - or when the vang is 'released' - the mainsail is vulnerable to large shape instabilities including sudden and uncontrollable 'power-ups' (and goose-wing accidental gybes, etc.) wherein the loose leech can 'spill air' but the luff section becomes over-drafted - the overall sail 'cord-depth' becomes deeper. In aerodynamic flow 'across' a sail, its the luff section that has the highest 'suction peak' hence 'drive component'.

A rigid vang (and in combination with a good traveller) especially allows one, with a 'flattened' sail, to 'blade-out' precisely which can affect a lessening the angle of attack to reduce the force on the sails ... and without vulnerable shape instabilities. A flattened sail is more stable at very low angles of attack and while partially luffing and m ost important has a more or less 'constant angle of attack' shape - easier to 'match the wind' or induce a more controlled 'luff'. With a rigid vang a fabric sail will behave more alike a 'rigid wing' which is ultimately more 'controllable' than a flapping/flogging/luffing mass of loose fabric which can sometimes cause major boat handling problems to the 'tripped' head, and grossly overtrimmed bottom panels.

With a loose vang the angle of attack will be 'non-constant' along the luff' due to the 'twisting', typically with the top sail panels luffing/flogging, the mid sections 'drawing' and the bottom sections severely 'overtrimmed' (to make the mid sections 'work') - a shape that no matter how you steer or trim usually MUST pass through a quite severe 'power-up' to attain 'any' other trim attitude.

Gradient wind (requiring sail 'twist') is only found in light to moderate conditions. In higher wind ranges (20+kts.) the gradient is usually only found 'very close' to the surface of the water (where the birds are now flying) usually well below the level of the boom hence there is NO NEED for 'twist' (other than what the sailmaker 'designed' into the sail). The lighter weight and faster the boat the more stable the boat will be when 'blading' with a flat, non-twisted, sail --- all needing a very powerful vang / rigid vang and a good traveller. When overpowered in the higher wind ranges and for *boat handling stability* its vastly better to "blade-out" and drop the traveller (with a flat untwisted sail) to very precisely control the amount of 'luff' ...... or simply reef.

 

[COOL]

What are the advantages and disadvantages of the two methods as far as trim control?

Neither have much impact on sail trim, except as cited above,
in very light winds when the weight of the boom alone will keep
the leech of the main too closed.
Some sort of boom vang should always be used,
but a solid vang has many advantages over a
topping lift, while eliminating any need for one.
A topping lift, if not removed while sailing,
will interfere with the mainsail roach when
tacking or gybing. They will generally wear on
the leech, leaving a mark and chafing the
seams.
A solid vang will function exactly like any other vang
tackle, except that it will also hold the boom up
when dropping the sail or reefing.
This feature is mostly 'out of play'
while the sail is set, just as a topping lift
should be.