SailNet Community banner

1 - 20 of 64 Posts

·
Registered
Joined
·
1,647 Posts
Discussion Starter · #1 ·
I have a vang that I hate and consider virtually worthless. I'm considering removing it and am looking for opinions. I get that on a smaller boat, the vang is very useful to shape the main as the wind increases. But on the configuration shown below with the mid-boom sheeting, I wonder if it is of any use. Upwind, no matter how much tension I put on it (as shown: 4:1, now rigged as 8:1), there is no change. I can get some purchase, but it's minimal - maybe an inch or 2 on an 8:1 rig. The angles are horrendous and I see no realistic way to improve them. So why bother at all? Off the wind, I use a preventer attached to an eye on the outboard genoa track which is very effective at bringing the boom down.

Should I ditch the vang and stay with the preventer? This discussion is not about rigid vangs, it's about whether any vang can effectively shape a mid-size main with mid-boom sheeting.


 

·
Once known as Hartley18
Joined
·
5,179 Posts
I have a vang that I hate and consider virtually worthless. I'm considering removing it and am looking for opinions. I get that on a smaller boat, the vang is very useful to shape the main as the wind increases. But on the configuration shown below with the mid-boom sheeting, I wonder if it is of any use. Upwind, no matter how much tension I put on it (as shown: 4:1, now rigged as 8:1), there is no change. I can get some purchase, but it's minimal - maybe an inch or 2 on an 8:1 rig. The angles are horrendous and I see no realistic way to improve them. So why bother at all? Off the wind, I use a preventer attached to an eye on the outboard genoa track which is very effective at bringing the boom down.

Should I ditch the vang and stay with the preventer? This discussion is not about rigid vangs, it's about whether any vang can effectively shape a mid-size main with mid-boom sheeting.
With the setup you have, it does seem as though the vang fixing point on the boom is a long way aft...

Within the range of your traveller, a vang will do nothing for your sail shape. If you're happy with rigging a preventer every time you're off the wind, by all means get rid of the vang.

(Personal note: I don't currently have a vang - my boat has never had one - and although I'd like one, I find either (a) a preventer rigged like you mention for long periods or (b) a spare crewmember for short periods works well enough. )

Nice boat, BTW :)
 

·
Senior Member
Joined
·
19,488 Posts
IMO the vang is a crucial safety item when sailing downwind. It prevents the chance of an accidental goose-wing gybe. It's a pretty important trimming tool any time the boom is outside the traveler range. Even before then it can play an important role in leech tension.

If you find it an ineffective tool it probably isn't powerful enough.

I wouldn't sail without one, even if it was nothing more than a fixed strop which would be better than no vang.
 

·
Barquito
Joined
·
3,685 Posts
I think that vang is set up correctly. It is about as far out on the boom as it is down from the gooseneck. Agree with others that if you don't want to set up a preventer, then the boom vang will keep the boom from riding up (it won't prevent the boom from gybing). Since I don't even have a traveler, the vang will be useful, even when close to the wind in keeping sail shape consistent as I sheet out in puffs.
 

·
Once known as Hartley18
Joined
·
5,179 Posts
I think that vang is set up correctly. It is about as far out on the boom as it is down from the gooseneck. Agree with others that if you don't want to set up a preventer, then the boom vang will keep the boom from riding up....
That's what the spare crew is for. :)

Since I don't even have a traveler, the vang will be useful, even when close to the wind in keeping sail shape consistent as I sheet out in puffs.
If you don't have a traveller, then you need a vang. The OP has a traveller (a shortish one, but a traveller nonetheless).
 

·
Registered
Corsair 24
Joined
·
4,594 Posts
I find preventers more useful especially on broad reaches and ddw...vangs not on every boat

long booms for example dont really need vangs but thats just my feeling and experience...

especially on old wooden boats...

now for dinchy sailing and small boat racing hell yeah

pull that vang down hard, get some bend in the boom and rake that b.................

jajaja
 

·
Registered
Corsair 24
Joined
·
4,594 Posts
IMO the vang is a crucial safety item when sailing downwind. It prevents the chance of an accidental goose-wing gybe. It's a pretty important trimming tool any time the boom is outside the traveler range. Even before then it can play an important role in leech tension.

If you find it an ineffective tool it probably isn't powerful enough.

I wouldn't sail without one, even if it was nothing more than a fixed strop which would be better than no vang.
for the newb sailor(no offence to anyone here) over reliance on vangs on downwind courses is the number one cause of boom failure, gooseneck failure and anything related to boom BREAKAGE

this is also true for improperly pullied mid boom traveller systems

this is why travellers(mainsheet) at the end of booms have such great records of non failure

for example my last boat had a rotating 4 point attachment boom end that in case of an accidental gybe what fails is the attachment point...and yes you lose the boom to the stays but you can quickly reatach mainsheet and have a nice sail...

booms that break in half are mostly caused when improper tension is exerted at a point too midway of the boom length...thats why you see massive pulley traveler systems on coachroof mainsheet traveller systems its needed...kind of like chosing your poison

My current boat is setup this way...but its a short IOR boom..so the forces involved are to an extent less than a boat with a big long boom and midpoiunt attachment

anywhoo

verbal diarhea out:D
 

·
Registered
Joined
·
1,647 Posts
Discussion Starter · #9 · (Edited)
Thanks for the sanity check guys. The other reason that I'm considering getting rid of the vang is that I'm upgrading the traveler with a Garhauser unit. The original doesn't move as freely as it should (even after rebuilding the bearings in the car). And even with the traveler blocks at 4:1 it's still hard to move to windward in 20kts upwind - and the traveler is how we predominately trim the main. My mainsheet trimmer will love me….

So while I'm upgrading the traveler, I want to upgrade the mainsheet blocks. As it is now, the vang interferes with the mainsheet block on the boom. I've tried double blocks, and two singles but they clang and don't let the mainsheet travel as smoothly as I'd like. So if I don't need the vang, I'll get rid of it…..it's not like I can't put it back.

FYI - I upgraded the stock 4:1 to 8:1 by hooking the 4:1 to a line that passes through a single block on the boom. So 2:1 gets doubled to 8:1. Pretty cool and simple.

It prevents the chance of an accidental goose-wing gybe.
I agree, that's why I hesitate and am questioning my logic.
 

·
Registered
Joined
·
5,067 Posts
From your pic, I might agree with Classic 30.
As I see several issues with your vang set up. (could be the angles of the pic, too)

1. the vang's connection to mast is higher than the absolute base of the mast. Looks like the geometry was chosen so that the present vang would clear an opened hatch. Getting the mast connection lower down will greatly help the vang generate more 'down' force on the boom.
Rx - do a trial with the vang pinned to the very bottom of the mast AT the coachroof. You can 'tie' a stout line around the mast base with a 'loop' (alpine butterfly knot, etc.) as the trial attachment point (w/ hatch closed).

2. From the pic, and I may be wrong, but I see a 5:1 vang being used @ 4:1 in the 'up' direction and 5:1 along the 'horizontal' direction, ..... the 'tail' of the vang seems to be running along parallel to the mast; and if so, the 'tail' is generating NO 'down' force !!!!!?????
Rx - even the vang control line should be run directly to the very 'base' of the mast.

3. Do a trial with the vang attached to the boom via 'strops/lashings' and with the 'strop connection' closer to the mast. A vang that makes a 45° angle with its boom will generate 40% more 'downforce' than a vang that makes a 30° angle intercept. (Of course when the attachment point on the boom comes closer to the mast, the 'moment force' becomes greater - a tradeoff, but should be investigated.) Your boom connection 'seems' to be a bit far aft on the boom.

Other - I often 'vang sheet' my boats (one has a Garhauer 'rigid' vang) when racing or just messing about. I initially pre-set the vang so that the boom meets the mast at a 90° angle (87° to be exact, as I have such marked on the vang control line). I can 'ease' the vang at will and under all wind strengths; but if the sail has a lot of developed wind pressure I can hardly ever be able to pull 'down' on the boom with a vang (10:1). To pull down with the vang (in above 'light-moderate' conditions), I always have to momentarily 'unload' the mainsail, reset the vang to the 'mark', then 'load up' again (takes few seconds). I dont know of many vang systems that will allow a fully loaded and drawing mainsail to be 'tightened' when the sail is 'loaded and drawing' (except when beating and the mainsheet is being over-tensioned, on purpose).
Usually most vangs require the mainsail to be 'unloaded' a bit before 'pulling in' on the vang.

;-)
 

·
Registered
Joined
·
1,833 Posts
I have a solid vang on my 42 footer, and I really think that all it does that is useful is to hold up the boom (even thought I have a topping lift, too).

Maybe a racer would get another .001 knots by using it somehow, but I think it's dead weight on my boat.
 

·
Registered
Joined
·
1,647 Posts
Discussion Starter · #12 ·
Thanks for the assessment, Rich. Some clarifications:

1. the vang's connection to mast is higher than the absolute base of the mast
The attachment point is just above the mast collar. In the photo, the vang is loose and you can see the lower set of blocks just above the bowline in the jib sheet. It's as low as it can go.

2. From the pic, and I may be wrong, but I see a 5:1 vang being used
I was wrong when I wrote 4:1, that was the original configuration. In the photo, it's 6:1.The 2nd set of blocks are obscured in the photo.

the 'tail' of the vang seems to be running along parallel to the mast; and if so, the 'tail' is generating NO 'down' force
That's true and could be reconfigured to go to the mast collar turning blocks. The manufacturer ran the lines that way for neatness, I suspect. Good idea.

A vang that makes a 45° angle with its boom will generate 40% more 'downforce' than a vang that makes a 30° angle intercept.
Agreed. The angles are horrendous. But if I move the boom attachment point forward to get 45 degrees, then the moment arm on the boom will be reduced. So I think that I will solve one problem and create another.

Your last paragraph is the most helpful. I'll look at when and how I apply vang. Thanks.

GROUP9:
I really think that all it does that is useful is to hold up the boom
True. The spring in the rigid vang is fighting the 4:1 or 6:1 block arrangement, reducing the down power. Rigid vangs are poor "vangs", IMO. They're mostly boom holder-uppers.
 

·
no longer reading SailNet
Joined
·
2,309 Posts
The vang isn't that useful close hauled. Your mainsheet has more downward force on the boom.

It should be useful when you are on a beam reach or deeper. In those conditions you would have traveled down to the limits of your traveler and the mainsheet can no longer be used to control downward force on the boom.

My first boat didn't have an effective traveler, so I used the vang all of the time. My current boat has a traveler that has a lot of travel and I don't get to sail on a beam reach that often (Puget Sound is long and skinny), so I there are many days of sailing where I don't touch the vang. However I'm still glad that it is there for those days when I need it.

My vang leads back to a clutch and cockpit winch. I don't use the winch with the vang very often, but it is there should I need it. The same winch is shared with the main halyard (it's primary use), outhaul, and first reef line.
 

·
Registered
Joined
·
5,111 Posts
True. The spring in the rigid vang is fighting the 4:1 or 6:1 block arrangement, reducing the down power. Rigid vangs are poor "vangs", IMO. They're mostly boom holder-uppers.
Well, I've gotta disagree with that one...:) I rate an effective vang as being pretty essential, and although rigid vangs can be pricey, I consider mine to be worth every penny...

The preventer arrangement you describe is a poor substitute for a vang in anything more than light to moderate conditions, in my view... I'm not a fan of mid-boom preventers taken vertically to a sail track or the rail, especially when the breeze comes up... An effective preventer needs to be led from the end of the boom to a point well forward of the mast, in my opinion, and when it's led back to the cockpit, it's an arrangement easily adjusted on any point of sail off the wind...


 

·
Registered
Corsair 24
Joined
·
4,594 Posts
those are the preventers I was talking about at least...jajaja anything mid boom for example is an easy way to break stuff

I like snubbers on preventers too...you know just in case! jajaja

again vangs are boat dependant definitely NOT mandatory on all boats
 

·
Administrator
Farr 11.6 (Farr 38)
Joined
·
9,762 Posts
I am reading this thread and shaking my head at some of these responses. I would have expected some of these responses back in the 1960's but not today. Like my estemed colleagues Ron, (Faster), Bob Perry and Jon Eisberg noted, to me a boom vang is a very critical piece of safety equipment that prevents the boom from rising up and taking out the backstay and rig in an accidental jibe. Those kinds of boom hitting backstay and taking down the rig or breaking a boom incidents were a pretty frequent occurances back in the day when boom vangs were not all that common.

A traveler is no substitute for a vang except perhaps when close reaching. A traveler only impacts the leech tension when the boom is perhaps 45 degrees of less off the centerline (especially with a coach roof mounted traveler). Beyond that the sail is free to develop too much twist. At that point you have a collection of over trimming or under trimming which implies a mix of bad trade offs; too much abrasion as the sail saws up and down on the rigging, too much twist making you more prone to jibing, broaching and rolling and too much weather helm. And a traveller does not come into play in the accidental jibe senario descibed above.

While you can rig a tackle to the rail that will act pull down on the boom and control twist, doing so is considered a very dangerous practice in heavy air, when you are more likely to dip a boom end from rolling or a knockdown and break something dramatically. Itwas extremely strongly discouraged at the safety at sea seminars that I have attended.

The preferred method of rigging a preventer is to take it forward to a turning block and then back to a quick release in the cockpit. The line should be stretchy enough to absorb an impact should the boom hit the water, but no so stretchy that it will allow the boom to reach within 30-40 degrees of the centerline of the boat.

Frankly, as I read Sabreman's description, it sounds like the problem is the geometry of the vang, and not that there is a vang in itself. Rich H is right that a vang should ideally be rigged at a 45 degree angle. Sabreman's vang appears to be at an angle approaching 30 degrees. Moving the attachment point forward on the boom to a 45 degree angle would increase the downforce by something like 20-25% while the lost leverage on your boom would decrease the mechanical advantage at the leech by 12-15%, overall a net gain. But the biggest advantage to changing the geometry is the massive reduction of load parallel to the boom on your gooseneck.

The good news is that an experiemental fix is cheap and easy. You should be able to rig a strop that wraps around your boom using either webbing or line at the right position and try it for a while. You will probably need to run a tight retainer line from the strop back to the original boom vang mounting position to prevent the strop from sliding up the boom under load.

I would also note, that my boom vang with 400 square feet of sail on an 18 foot boom, is 12:1 and is led back to a winch. I originally had second cascade which resulted in a 24:1 but still found myself using a winch in heavy air.

Jeff
 

·
Registered
Joined
·
5,067 Posts
The vang isn't that useful close hauled. Your mainsheet has more downward force on the boom..
The prime function of the vang is to control 'twist' in the main. Unless you have a radial traveller that goes from rail to rail and you dont touch the mainsheet pressure ... when the boom is moving across the traveller, the amount of twist in the main will be changing. Twist sets the angle of attack for all levels (up from the deck) of the sail; If the twist becomes variable and changeable, the efficiency of the sail becomes less, usually much less ... even in some cases to become subject to sudden 'power-ups' when in very gusty conditions. Also too a sail with a inadequate vang system will require constant 'trimming' as the wind pressure varies; and, its very rare to have constant wind pressure.

A sail that is 'twisted' to match the gradient wind is easy to 'blade out' (the entire luff 'breaks' instantaneously) when overpowered; a sail that doesnt have reasonably good matching twist can either 'power-up' or will be 'unattached' at the head and overtrimmed at the foot with only the mid panels 'working'. If you attempt to luff-up with a grossly mal-twisted sail, something aloft is 'going' to 'power-up' when you do.
The easiest way to keep 'constant twist' is via a 'good' vang system ... and especially when the boom is no longer directly above the traveller (thats why 'vang sheeting' works so well). Even when the boom is more or less directly above the traveller, sail pressure will cause the mainsheet to not be perfectly 'vertical' ... and the vang is indeed helpful to keep the 'tack angle' of the sail (or boom to mast angle) more or less constant, and without much change in mainsheet tension (that tack angle being held constant also results in constant fore/aft position of maximum draft in the sail).

A sail whose twist is 'variable' with wind pressure will be changing its 'aerodynamics' up and down along the vertical (luff). in the high speed planing hulled sport boats with inadequate vangs ... we call those folks: 'swimmers'.
In long distance sailing I feel its always better to be 'on' with trim and shape as a 22 hour day is usually more satisfying than a 24 hour day, especially when 'getting out of the way of stink'.

Simply put, no vang = increased vulnerability to a 'goose wing' gybe. A 'goose wing' gybe can easily change a mainsail into a spinnaker when all the slugs on the luff break free from the mast.

;-)
 

·
no longer reading SailNet
Joined
·
2,309 Posts
The prime function of the vang is to control 'twist' in the main. Unless you have a radial traveller that goes from rail to rail and you dont touch the mainsheet pressure ... when the boom is moving across the traveller, the amount of twist in the main will be changing.
You quoted me saying "The vang isn't that useful close hauled. Your mainsheet has more downward force on the boom."

Nothing that you've written disagrees with that. When close hauled the mainsheet on his boat has greater purchase and better leverage on the leech of the sail then the vang does on his boat. I'm not surprised that he can't control twist better with the main than the vang. Once the main sheet has the boom where he wants it he can tighten the vang to hold it there.

The traveler position hasn't made a gross change in sail twist as you travel across the range on the boats that I've sailed on. On my Pearson 28-2 it closes twist slightly at the extreme ends of the range, but typically by the time I'm there I've also switched to using the vang to control leech twist. I have little experience on boats over 30' and perhaps the geometry there does make a bigger difference.

I am pro-vang and added the missing one back to my boat. I just don't think it is likely to be that effective compared to the main sheet for controlling leech twist when close hauled, as shown in the photo at the start of this thread.
 

·
Registered
Joined
·
9,378 Posts
I am with Rich, Jeff, Bob, Jon and Ron.
 
1 - 20 of 64 Posts
Top