Our 1999 model came with a solid vang, meaning it uses lines and blocks to bring the boom down, at the same time compressing a spring inside the telescoping vang. When you ease the control lines, the spring extends the vang, holding the boom up. It would allow you to remove the topping lift completely because the vang holds the boom up.

As for usage, it becomes pretty important when reaching. If the boom is over the cabin top traveler, the mainsheet will adjust your leach tension and much of your sail shape. As the apparent wind comes more aft, you could ease the traveler with the mainsheet tension never changing. Once you reach the end of the traveler, you must start to ease the mainsheet to move the boom farther out, but without a vang that will allow the boom to rise and the leach tension to change, which you might not want.

By using the vang, you set the leach tension where you want it and as you ease the mainsheet, the boom will swing out with the leach tension unchanged.

More advanced sailors than I may have some better details for you, but hope that helps.

Think of the angle of your mainsheet between boom and traveller. Sheeted in and going upwind, you have the traveller for lateral adjustment and the sheet is roughly 'vertical'.

Downwind eased out, the mainsheet is now almost horizontal and is making the lateral adjustments, vang is the only option to make 'vertical' adjustments of the boom.

Because our sheets are so far forward on the boom anyways, I don't worry too much about the vang loads at the boom end. They are not way different than the mainsheet loads going upwind.

The two places the vang loads will be noticed are the lower (mast end) attachment and the gooseneck.

The bottom of the vang is actually at possibly the strongest part of the mast, because it is braced where it goes through the deck. So not an issue for rig integrity. however you do need some serious hardware to avoid breaking the attachment point in a jibe.

The gooseneck tends to see significant lateral loads when broad reaching with the vang on. My experience is that these loads are sort of exponential, ie. if you bear away with the vang really tight, the loads go through the roof, but easing one or two inches of vang can knock down the loads by 1/2 (it seems like). A 24 footer I had could easily break the lower vang attachment if you didn't ease a bit of vang when bearing away from upwind trim.

Certainly sailing deep downwind a vang makes a huge difference in efficiency of the mainsail and in safety. An unvanged sail will typically see the boom ride up and up and up which can cause unwanted crash jibes, and also make it very hard to perform intentional jibes.

On a related issue: Is it possible for the spring in a spring loaded vang to lose some of its strength? It seems to me that when I try to center the boom, the sheet brings the boom down more than to center. So, for instance, when I leave the boat, I try to tighten the sheet enough that the boom cannot swing back and forth. In order to do this, I end up bringing the boom down so low that it's almost on top of the dodger and is about at head level of a pretty short person. (I have a roller furled main, if that makes any difference.) I'm thinking that if the spring in the vang were stronger, then it would put enough tension on the sheet to prevent the boom from swinging without allowing the boom to drop so low.

What say you?

John,

I don't suspect your situation is abnormal. Mine does the same thing, and spring tension shouldn't be real factor.

Think about the fact that the mainsheet is pulling the boom straight down against the spring. The boom is still free to swing somewhat at the gooseneck and no amount of tension is going to stop it, just reduce it.

If we are at anchor for more than a day and I am distracted by the boom swaying, I just tie a line from the boom to the coach hand rail. If you get the mainsheet and extra tie acting in a triangular geometry, you can keep the boom completely stationary.

Cheers,

Tao has a line vang setup. So, I can adjust the boom and all that. Question though, aside from a solid vang holding the boom up (can eliminate the topping lift), is there really any advantage to a solid vang over a line vang? For cruising and the occasional tin can race, does an investment of many boat bucks add anything that would be really obviously different?

Dan

S/V Tao
Hull #114

The vang controls twist. In light air the solid vang supports the boom so that the weight of the boom doesn't distort sail shape. This is true even if you are sheeted in to where the boom is over top the traveler car. Of course, if wind is that light and you are not racing then the 3-6 rule is probably in effect.

I like my normal vang/topping lift setup simply because the hardened mainsheet/vang gives me a solid boom to lean on when flaking the main.The rigid vang feels squishy when working on the boom.

Bud, you need a vang for two reasons: one - to flatten the main going upwind; two - when running to flatten the main (which also prevents the sail from drooping around the spreaders). When "power" reaching in heavy wind, the vang is loosened to drop air off the top (leech) of the main, or else you just keep rounding up.

Upwind you want the main flat in light air so vang,, medium air loose, heavy air tight.

I take major issue with the idea that the vang can flatten the mainsail. Not going to happen.

Upwind the vang should always be either loose or no more than 'snug'. The mainsheet controls the boom height upwind, and therefore controls the twist and the leech tension. 'Flatness' is a function of mast bend, cunningham/halyard tension, and outhaul tension.

In wind over about 12-14 knots you MAY start using the vang upwind, or you may just lower the traveller.

On a reach the vang becomes important and also downwind.

A Solid vang can be helpful to lift the boom up in light air, and certainly for racing would be preferrable to a topping lift. However it is not as effective as a topping lift when the boat is moored and for sailing speed there are better places to spend your money.

I would consider the solid vang a 'nice to have' rather than a 'need to have'.

Jason, with our mainsheet fully in, our rigid vang moves the boom down and flattens the sail. The soft vangs on our C22 & C25 did the same.

I have to agree with Jason here as to the role of the vang. On a C36 the outhaul and the halyard are about the only controls that flatten the main. On many boats the backstay can be used to bend the mast and really flatten the main, but the C36 section is really stiff so backstay just helps with the forestay. Pulling the boom down, whether you do it with the main sheet or the vang reduces twist and closes the leech. If the boom is over top the mainsheet car then the main sheet is going to exert a lot more downward tension on the boom and leech of the main then is possible with the vang. After all, the mainsheet is pulling straight down and the vang is pulling at an angle. On the wind, with the main sheeted in, the vang does nothing. It is only when you ease the main sheet that the vang starts to control twist. If you don't want to use the traveler you could tension the vang and then ease the main sheet either as you bear off on a reach or just need to depower, but the traveller is reallly a better control so we normally control twist with a mixture of traveller and main sheet until the boom is eased out past the end of the traveler. At that point we use the vang to control leech tension (and twist). Jason makes a good point about vang tesion in heavier air reaches. Easing the vang opens the leech and depowers the main. On our Olson 25 we kept a crew on the vang for heavier air reaches/runs charged with dumping it whenever we started to round up. Sometimes it worked.

Mike, I don't disagree that the mainsheet provides a lot of power. All I suggest is that you two-block your mainsheet with no vang, then pull on the vang. You will see a change in boom position and, hence, sail shape. Not much, but it's there.

On my C30 I had a rigid vang and really liked it for tuning the shape of the sail. I will be purchasing one for this boat as well. Does anyone know what model is reccomended by Garhauer for a C36 MKI

[QUOTE=Wavelength;11155]On my C30 I had a rigid vang and really liked it for tuning the shape of the sail. I will be purchasing one for this boat as well. Does anyone know what model is reccomended by Garhauer for a C36 MKI[/QUOTE]

I replaced the rope vang my 1987 MK 1 and I used the Garhauer model RV20-1 SL
If you look at the July 2009 issue of Jibsheet, there is an article I wrote on how to install it. It's located here: [url]http://www.c36ia.com/node/1458[/url] , but you need to be a member to read it.

I hope this helps.

Upwind the vang is used in heavy air to hold the boom down when you ease the mainsheet in a gust. When you trim the main hard hard the last foot or so mostly pulls the boom down. In order to maintain sailshape if you dump the sheet in a gust you want the boom to move off centerline, not up. This helps keep the leech tension. All you do is snug it when the mainsheet is trimmed all the way in. Don't tighten just remove the slack.
Mostly a racing thing.
Alternately, you can dump the traveller which will do the same thing. .
Vang off in light air or you will be SLOW.

Usefull in heavy air downwind also to keep the boom down.
And reaching as mentioned earlier.