Boom Vang

[danstanford]

Wasn't the premise that ADDING a vang would be adding a safety device? Not having a vang would remove the need to release or ease it.
I am certainly not arguing against a vang, just wondering how adding one would be adding a safety feature.

 

[jssailem]

how adding one would be adding a safety feature.

You are correct in my thinking. A Vang is a trim control tool. I do not know any special safety functions it provides. It does help to keep the boom in a fixed plane... yet the boom is free to swing sweeping across the deck.

 

[lakesurfsailor]

Picture show the boom is Z spar. View 4 shows an eye for attachmentl Are there two of them one for the boom vang and the other for the mainsheet

there are 2 attachment points, one is probably for the vang but I will have to check the angle when we launch this season. Thanks again for all the advice

 

[lakesurfsailor]

Picture show the boom is Z spar. View 4 shows an eye for attachmentl Are there two of them one for the boom vang and the other for the mainsheet

I just found ZSpars website and catalog- this must be my mast plate! This diagram is super helpful and shows that this must be designed to take the load of the vang. I will call tomorrow morning when they open. Cant thank you enough!

Catalog link:

https://www.usspars.com/wp-content/uploads/2011/03/preY2KCatalog.pdf

 

[Joe]

The vang's primary purpose is to stabilize the boom (prevent bouncing) when it is swung outside the range of the traveler. The skipper will call "vang on" when the mainsheet is no longer effective at controlling leech tension. Now the vang takes over the boom's vertical movement while the mainsheet is relegated to replacing the traveler's lateral control function.

If conditions change quickly, (perhaps an intense wind gust) the boat will often try to round up violently, heeling over severely, threatening the loss of rudder contact, resulting in a broach. The skipper calls "vang off" to avoid burying the boom into the water so the boat can get upright, avoiding further catastrophe while the crew recovers control of the boat.

I have never thought of the vang with a "power up" or "power down" mentality.
I had always visualized it as an upwind or downwind tool.( Upwind - no.....downwind - yes.)
But, for me, over time, the vang has evolved to a simple question: "is the boom bouncing".
Heh, heh... just gettin' lazy, I guess.

 

[Hollyberry]

Re vang as a safety device....
This comes from the classic 'Royce's Sailing Illustrated' (image credit)
When sailing deep downwind without a vang the mainsheet has no downward component, leaving the boom free to lift if any forces cause it to do so.
Esp. in a big sea with lots of motion, a gibe, accidental or otherwise, can turn into a goosewing (half the sail fills on one side, the other half on the other. Now the leech is a big S curve with the boom at a high angle , but eventually the sail will decide with way to go. Now the uncontrolled boom can slam violently to the extent of the mainsheet - if it's still cleated - and fetch up hard. This might break fittings, or do other damage possibly including striking a shroud.
I've only experienced this in a small sailing dinghy but thereafter we added a fixed strop as a 'vang' and it never happened again. On a larger boat the potential forces would be exponentially higher.
And I think a vang (as a safety device - fixed or adjustable) is especially important when newbies are learning.

Most of the time, agreed, it serves as a leech tension trim control, with a spring loaded or hydraulic one capable of up and down adjustment...

Sermon over......

 

[jssailem]

Sailing down wind, a smart sailor applies a preventer.

 

[Hollyberry]

Sailing down wind, a smart sailor applies a preventer.

AKA a 'toerail vang'.....

 

[kappykaplan]

AKA a 'toerail vang'.....

Never heard that terminology applied to a preventer before!

 

[Stiknrudder]

All good discussion and largely what I understand a boom vang to do. My understanding is far less sure and far more vague concerning a hard vang or in my case a Seldén RodKicker. I believe the rigid portion's purpose is to help prevent as Joe posted "bouncing". Bouncing obviously has and up and down component and a normal block and tackle vang can prevent most of the up but not the down. So I assume that is largely the purpose of the rigid portion of the RodKicker.

However, more confusing still for me is the fact that the RodKicker has a gas spring component...again this makes perfect sense in helping to control bouncing, it is basically serving the same function as shocks in your car's suspension, it dampens any up and down oscillations. The confusing part for me is that the gas spring is "optional" and apparently Hunter and/or the previous own decided not to take that option. Therefore on my rig, the RodKicker sits in a mostly or completely compressed state (The first image I attached is the RD installed on a 44DS) all the time and does little to control downward motion beyond bottoming out.

I'm looking to add the optional gas spring to my RodKicker but I am concerned about the way the device is installed on my rig, and the fact that it is basically bottomed out all the time. when I look at the install on a 41DS (second attachment) the generally appear to be extended more and have more room to absorb up and down motion. It almost seems as if the RodKicker 30 (the RD model installed on the 44DS) is too big for the application and the RodKicker 20 is better sized for the 41DS. I'm worried that if I install the gas spring on my RD 30, it will force the boom up at an abnormally high angle and I will have to crank down excessively on the mainsheet and/or vang to control that especially when not under sail. Any thoughts would be greatly appreciated.

 

[ice breaker]

I am not sure what boat you have, but on our 41AC, the rod kicker is primarily used to hold up the boom when the sail is not deployed. It sits in its fully compressed state. It keeps it about 6-8 inches above the arch. Your picture shows that. When sailing the rodkicker/boom vang allows for shape changes. I find it very useful. We are on our 2nd set of sails and every sailmaker cuts sails differently. I had to relearn a new technique with the new UK sails. Always release the rod kicker before deploying the main sail. The gas spring is not needed at all.