What good is a boom vang?

goldenstate

Sustaining Member
Blogs Author
Novice sailor question/observation here:

In what situation(s) do you find that your boom vang adds value to your sailing?

My main sheet connection points are only 2-3 feet outboard of the vang connection. The vang pulls down at a forward angle, while the main sheet pulls straight down toward the top of the cabin, but in both cases I am pulling the boom down. I suppose the vang would permit me to pull down on the boom and keep the sail flat even if I am sheeted out all the way going downwind.

I'm sure I need to learn more about sail trim, but if anyone can enlighten me as to when I should expect my vang to make a substantial difference in the performance of my boat (or your own boat) I would appreciate it.

My own vang has been used decoratively for the most part up until now.

Thanks in advance.
 

bgary

Advanced Beginner
Blogs Author
For sail trim, your vang lets you adjust the shape of the sail, whether the mainsheet is eased or not. So, yes, that means that you can maintain the leech shape you want even when reaching or running.

Also, the vang prevents the boom from "skying" when gibing in heavy winds.

$.02
Bruce
 

Milagros

Member II
Hi Tom,

I'm definitely not an expert but have been studying sail trim and playing with it a bunch over the past few months. Corrections welcome if I've giving bad advice. Here's what I think I understand:

In general (but not absolutely), its better to have a flatter main in heavier wind. A flatter sail produces less lift and less drag-so less heal and more speed in practical terms. So if you are reaching especially the boom vang helps keep the sail flat. When it gets very heavy, and maybe you are trying to put off reefing, as long as your outhaul and downhaul are nice and tight, you can let a little out vang and let the sail twist, dumping some of the wind from the top of the sail and taking pressure off the leech. That moves the center of lift forward towards the mast and can reduce weather helm.

In lighter air, with more of a belly in the sail, more twist is often desirable because the wind velocity near the surface can be significantly lower than it is at the top of the mast. Play with the vang and watch the tell tales on the leech of the main. It can be a challenge to get them all flying.

Running directly downwind in light/medium air, you often want to have a taught vang so the sail is as stretched out as possible to create the largest obstacle to the wind that is pushing you along.

Hope the helps, and that I'm not leading you astray.
Ian
 

goldenstate

Sustaining Member
Blogs Author
This all makes sense, thank you.

I suppose my real problem is that I like to keep my boom lifted a couple of inches above my head in the cockpit. But if any load is on the boom lift, the vang can't have much of an influence on the leech of the sail. This means clambering up on the cabin top to release and then retighten the boom lift every time the sail goes up and down.

I guess this issue is what leads people to rigid vangs...
 

markvone

Sustaining Member
Tom,

Having any lift on the boom via the topping lift will not allow the mainsail to "hang" into it's designed shape. This should cause some bagginess along the mainsail foot and reduce leech tension. This will impact upwind performance, sail too full and not as aerodynamic. And yes, this will stop any shape changing influence of the main sheet tension because it will be tensioning the topping lift and not the mainsail fabric. The mainsheet pulling down (on the mainsail fabric) adds leech tension.

The angle of attack will change with the traveller moving sideways but the mainsail shape will not. My sailmaker taught me a long time ago "sheet for shape, traveller for trim". As the mainsail is eased out to the outboard end of the traveller, off the wind, the mainsheet is no longer pulling the mainsail fabric straight down and the mainsail can loose leech tension and it's shape will get fuller. The vang can pull the boom straight down with the boom all the way to the shrouds, restoring leech tension and shape.

All this matters more for your large fractional main much more than for my short, tall IOR masthead main. And YES! the rigid boom vang holds the boom up all the time. No topping lift to mess with - ever.

Mark
 

goldenstate

Sustaining Member
Blogs Author
Thanks Mark!

What kind of a rigid vang do you have and would you recommend it to others?
I am thinking about updating the blocks and line for my soft block-and-tackle vang or converting to a rigid one.

(FWIW the 32-200 is a masthead sloop rig carrying only 207sf in the main and 287 [sailboatdata.com numbers] with a standard jib.)
 

Bepi

E27
Relative novice here. I notice a big difference when using the vang. The longer your sheet is extended the more line is available for "play" which lets the boom rise and then the leach of the sail bows and the sail spills wind, the vang allows less play in your main sheet so you get better power from your sail.
 

Teranodon

Member III
....
What kind of a rigid vang do you have and would you recommend it to others?
....
I recommend getting your rigid vang from Garhauer. It's a small company, and they will work with to ensure that you get a vang that fits your boom, and that has the right size and the right spring. I recommend their blocks as well.

More than the sheet, the vang/traveler combo is the boat's "gas pedal". A rigid vang is a thing of beauty, and it lets you get rid of the hated topping lift.
 

toddster

Curator of Broken Parts
Blogs Author
Dunno… a sturdy topping lift is what you need if you ever need to use boom & mainsheet as a crane - to lift a MOB, outboard motor, or the engine, for example. And I’ve seen a few boats at anchor for a week that use it to lift the boom clear up out of the cockpit.
Also, I figure the 3:1 vang with snap shackles is my emergency block and tackle to fit between the halyard and LifeSling if that ever has to be deployed.
But yeah, going down wind without a vang is just an exercise in futility. I suppose this is most obvious with end-boom sheeting. At some boat size, a rigid vang with hydraulics becomes de rigueur, as the forces become to great for rope tackle. Not sure what size that is… >40 ft-ish?
 

kiwisailor

Member III
Blogs Author
I installed a Garhauer vang on my E38 it's a top quality piece of gear and an excellent investment to control the boom and mainsail shape. Also can be used in place of the need of a topping lift. My vang control line is brought back into the cockpit.
 

markvone

Sustaining Member
Tom,

I somehow got into my head that you had an E33RH even though your post signature shows E32-3.

I have an older Hall Qwik Vang which works great but I don't know if this model is state of the art any more. Also, a rigid vang can be an investment so searching for one that works well at a reasonable price is worth the effort, Garhauer consistently gets recommended by other Ericson owners.

I have replaced all my original Schaeffer mast base and other blocks with Harken ball bearing blocks. Also have new organizers. Makes a huge difference. If you can't adjust your control lines easily, you won't use them. My vang started as a factory cascaded 4:1 x 5:1 purchase (20:1 overall) lead aft on one side of the cabintop (pink line in picture). I added a block to the end of a new control line (now white) on the vang and a pair of blocks at the mast base and ran a new control line (bright red) to each side of the boat. This gives me 40:1 on either side of the boat.

Mark


IMG_0115.JPGIMG_2938.JPG
 

paul culver

Member III
As pointed out the vang's usefulness kicks in down wind when the main sheet no longer has significant downward pull on the boom. When cruising you can optimize the vang angle of pull by attaching its lower end to the leeward toe rail. This also provides a preventer in the case of an accidental jibe.
 

tenders

Innocent Bystander
Dunno… a sturdy topping lift is what you need if you ever need to use boom & mainsheet as a crane - to lift a MOB, outboard motor, or the engine, for example.

I'd expect that using a topping lift like this would break it. Mine is 1/16" wire and its attachment points on the masthead and boom do not have very much "meat" to them. And topping lift rigging that would support a MOB procedure would introduce a significant amount of weight and chafe aloft that would almost never be used.

When the boom is pressed into service as a crane, the main halyard should be attached to it, at/above the point of loading. That way there is almost no bending force applied to the boom, only compression in column, which is the dimension of the boom's structural strength, as well as pressure at the gooseneck.

The rigid vang shouldn't be used as a substitute for the main halyard in crane mode, either. The boom will bend easily.
 

toddster

Curator of Broken Parts
Blogs Author
the main halyard should be attached to it, at/above the point of loading
Right you are and I have a bail opposite the mainsheet attachment specifically for that purpose. Haven't used it in so long it slipped my mind.
The PO never properly rigged my topping lift anyhow, so I replaced it with 5/16 dyneema that ought to hold anything I'd actually hoist. The shackle at the top might bear some consideration though. All somewhat redundant now that I've finally finished the stack pack/lazy jack system.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
When the boom is pressed into service as a crane, the main halyard should be attached to it, at/above the point of loading. That way there is almost no bending force applied to the boom, only compression in column, which is the dimension of the boom's structural strength, as well as pressure at the gooseneck.
Yup. That is what we did to swing our old diesel out to the dock and then lift the new diesel on board.
 

windblown

Member II
We have a on a old Garhauer rigid vang on Tradewinds, our 32-3, and it works well for us. We also still have a topping lift, because we have a Dutchman sail flaking system. Best of all worlds.
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
In my opinion all you need as a vang is a block and tackle, and also a reliable topping lift. The vang keeps the sail flat when the boom is let far out, and a block and tackle vang can be relaxed to allow a hatch to open or removed for other purposes (such as man-overboard recovery).

Rigid vangs are very popular and expensive. Whether better than traditional block and tackle depends on the boat and the case.
 

Teranodon

Member III
Everyone sails their boat their own way - that's our motto here. For myself, I find that the vang is useful even when going to weather. Thus, I use the traveler and sheet to get the boom near the centerline. Then, the vang opens and closes the leech for more/less power and more/less heeling moment. I loathed my topping lift. It would snag the roach of the sail. So I got rid of it. I park the main halyard on the end of the boom.
 

toddster

Curator of Broken Parts
Blogs Author
Should have snapped a picture yesterday - Dog has a habit of getting tangled up in the boom vang. If he's leashed, he'll wrap and weave the leash all through the vang. Yesterday, he just got his hind legs stuck in it somehow ???? Attention-seeking, I suspect.
 
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