boomkicker/vang quandary

[sinnettc]

Ran into a bit of a quandary this weekend when we were overpowered and I think I may be missing something on twist. Or maybe it's the way my rig is set up that's confusing me.

I play the traveler in puffs and use the genoa/jib tracks to manage twist in the jibs (98% blade or 135 genoa). It's the main I'm concerned with here.

I have a Capri 22 Tall Rig with a boomkicker. Because the boomkicker forces the boom up, I have to use the vang to help manage sail shape 100% of the time. Looking at the racers, I see their booms pulled down and fairly flat sails all the way to the top, even when the wind is honking. I have a racing main.

So here's my quandary - it seems like I can induce more twist at the top by letting the boom rise, which means easing the vang. But it also seems to me that raising the boom makes the sail fuller down low, so maybe it defeats the purpose when I'm trying to depower? Either way, all 4 telltales fly (3 when reefed). Am I defeating the point by letting the boom rise or is that what I need to do to depower it? Maybe I'm letting to go too high?

 

[Joe]

I suggest using the mainsheet as your primary twist control in upwind settings.

I don't see what the issue is with a boomkicker vang. Just forget about it when the boom is in close.

Whether you have a boomkicker or a rigid vang as I do, using the mainsheet when the boom is in close is my choice for setting twist.

Think in terms of "opening" and "closing" the leech..... then it's easier to visualize what happens when the sheet is eased.

Don't forget your other mainsail controls...... halyard and cunningham for draft postion, outhaul and mast bend (backstay) for draft depth.

 

[Al1653]

I agree with Joe. The vang is used to control the up and down movement of the boom when it is out over the side of the boat and the main sheet is of no use. The primary sail control to keep the boom from rising when it is over the cockpit is the main sheet. The vang can also be used to assist in flattening the main in heavy weather although it should not be necessary as main sail area is reduced as reefs are applied.

 

[RichH]

I agree with Joe .....
Also when you are 'twisting off' in heavy winds, especially in turbulent unstable winds, a 'twisted off' sail can easily and radically (and unexpectedly) 'power up', then 'power down', and cycle through both.
Twist and windflow gradient is usually not a factor in the higher wind speeds (unless you have an exceptionally short mast which is below the zone where all the seabirds are flying - at near the tops of the waves); the amount of twist of sails is usually more important in 'lighter winds' ... typically 0-5 knots.

In practice its usually better either to 'blade out' using the traveller and/or the tight vang + mainsheet (called 'vang sheeting) to precisely control how one depowers .... using 'just' the leading edge of the luff section or sections of the leech (fisherman's reef) 'working' to control the angle of heel, etc. ... the other sections of the sail are luffing/stalling, etc. 'as needed'. In 'blading out' only 'portions' of the sail are 'working' and you do this in a controlled manner via traveller or by 'vang sheeting'.

The vang system's most important function is to prevent a 'goosewing gybe', etc. where the boom raises, the draft gets deeper (power-up) .... and 'over she goes', the use of 'traveller dumping', etc. will do almost exactly the same .... keeping the boom from 'rising' and the sails from unexpectedly 'powering up', etc.
With a rising boom it becomes very difficult to control because the leech is 'loose' and may become S-curved (and with a 'moving' or changing S-curve) and with quite 'unpredictable results' that can rapidly change the shape/draft position/amount of draft, etc. "Blading-out" usually is 'easily' controlled and with more 'predictable' results for controlling the boat. With respect to jibs, the shorter the LP the easier and more consistent the 'blade out'..... of if you have a boat with a sensitive and very reactive helm you simply 'feather up'.

------- "blading out" is 'feathering up' by use of the traveller or by vang-sheeting, etc. while keeping the rudder 'quiet' and the boat essentially kept on a straight line course. "Blading out" is faster to do than feathering up by steering ... because of the momentum of the boat is much greater than the momentum involved in sail trim.

;-)

 

[sinnettc]

I suggest using the mainsheet as your primary twist control in upwind settings.

I don't see what the issue is with a boomkicker vang. Just forget about it when the boom is in close.

Whether you have a boomkicker or a rigid vang as I do, using the mainsheet when the boom is in close is my choice for setting twist.

Think in terms of "opening" and "closing" the leech..... then it's easier to visualize what happens when the sheet is eased.

Don't forget your other mainsail controls...... halyard and cunningham for draft postion, outhaul and mast bend (backstay) for draft depth.

Ok, that makes sense hard on the wind, And the kicker doesn't really have any effect when the boom is hauled in tight, but as I ease the sheet to foot off the kicker forces the boom up. In light wind the kicker will totally mess with the shape anywhere but close hauled. I'm talking 15-20° up angle and a huge bag in the sail. Exactly the shape a vang fights downwind I think.

I'm not familiar with how the solid vang works. Does your solid vang apply upward pressure to the boom all the time or only when you set it on a downwind run? By design the Boomkicker is like an archery bow and always under tension, forcing the boom up regardless of point of sail until close hauled. So as I ease the sheet the boom rises more than it would with no kicker. I manage that with the vang.

I think what I was trying to get to is at what point is the back end of the boom too high and does the fuller, baggier shape low offset the benefit of the twist at the top?

Btw I got a "you were fast" after tonight's beer can, but the wind was light and I wasn't trying to twist off the topto de-power

 

[Joe]

I ease the sheet to foot off the kicker forces the boom up. In light wind the kicker will totally mess with the shape anywhere but close hauled. I'm talking 15-20° up angle and a huge bag in the sail. Exactly the shape a vang fights downwind I think.

AHA!!!! you have exposed the fundamental flaw of the boomkicker when compared to a rigid vang.... The boomkicker's design requires that it constantly be restrained because the rods are always bent... and they want to be straight.... so it is always pushing up on the boom, rather than simply supporting it.

The rigid vang is designed to support the boom in a neutrall position... but still allow movement above that position.

There is no neutral position with the boomkicker. Yes you could tie a stopper knot in the control line... but then you would restrict any further upward movement if lots of twist is desired. Or.. you could attach a restraining line between boom and mast with a quick release feature...but..that's a hassle...

Don't get mad at me for suggesting this... but if the boomkicker is inconvenient... take it off and sail without for a while.

Now, here is the frustrating fact.... you can purchase a Garhauer rigid vang for your boat for not too much more that the price of the boomkicker system.... $275 for the RV12-1

http://garhauermarine.com/catalog_process.cfm?cid=40

The advantage is obvious... the rigid vang does not keep constantly pushing up on the boom... you release the control line...it doesn't interfere with your trim... Your quandry is no more.

I think what I was trying to get to is at what point is the back end of the boom too high and does the fuller, baggier shape low offset the benefit of the twist at the top?

I think that's what the tell tales are for. trust them. If the bottom telltales disappear... you're overtwisted.

 

[sinnettc]

Aha indeed!

The way the rigid vang works does seem like a better approach to me and the price for the garhauer one you posted isn't obscene. I might see if I can get a closer look at one of the boats in the marina that has one. Just need to decide if that's the route I want to take and where it fits in the upgrade list.

We did try sailing without the kicker for a while when the PO's home-made acrylic boom mount failed explosively. My wife took a pretty hard hit on the head one day because the boom dropped during the tack instead of rising (we weren't close hauled). That's not to say sailing without the kicker might not be worthwhile, it's just a comment on one of the pluses of the kicker and my failure to realize that the boom would be lower the first time we came about without it.

Thanks for the info.

 

[FourPoints]

AHA!!!! you have exposed the fundamental flaw of the boomkicker when compared to a rigid vang....

I have a Z-Spar rigid vang and it operates effectivly identical to a boom kicker, I always control the vang's lift with the vang sheet, and I've found that (particularly in light air) it improves performance as the boom is never weighing down the main affecting the shape of the main.

I view the fact that on any point of sail it allows you to either lift the boom, or pull it down, with a single control line, to be the single biggest reason to install my rigid vang (although eliminating the topping lift to be a close second!).

 

[Joe]

I have a Z-Spar rigid vang and it operates effectivly identical to a boom kicker, I always control the vang's lift with the vang sheet, and I've found that (particularly in light air) it improves performance as the boom is never weighing down the main affecting the shape of the main.

I view the fact that on any point of sail it allows you to either lift the boom, or pull it down, with a single control line, to be the single biggest reason to install my rigid vang (although eliminating the topping lift to be a close second!).

The point of the rigid vang is to support the boom..... not to lift it beyond a useful level. The vang tackle pulls the boom down... the springs, or pneumatic piston, return the boom to its neutral postion... thus eliminating the need for a topping lift. The limited lift of the rigid boom's design allows it to support the boom without needing to adjust the control line.

If the rigid vang pushes the boom up higher, past the neutral position, and thus needs restraining like the boomkicker system, then it has been improperly installed.

 

[sinnettc]

Here's a very short clip of what happens when I ease off the main.

https://vimeo.com/43232792

 

[Joe]

That was quick, chris... but I can guess what happened. You know I was thinking that a weaker set of rods could solve the problem... is that something boomkicker offers. Or... maybe one rod instead of two.. I don't know..just looking for a reasonable solution

By the way..... I love the Capri 22....

 

[Todd Smith]

Joe,

The height that a boom kicker will raise the boom is dependent on the installed geometry. If the attachement point is moved aft on the boom, the boom will be lowered. Some models have adjustable slides for this purpose. You might also be able to shorted the length of the rods.

Todd

 

[Joe]

Joe,

The height that a boom kicker will raise the boom is dependent on the installed geometry. If the attachement point is moved aft on the boom, the boom will be lowered. Some models have adjustable slides for this purpose. You might also be able to shorted the length of the rods.

Todd

Aha! An informed voice... thanks for the explanation, Todd.

You know I thought about that a lot last night... and it makes sense that moving the boom bracket aft would reduce the recoil on the rods... similar to the way a rigid vang is installed. So perhaps Chris' dilemma is caused by an improper installation..... in oither words the "bow" is arched too tightly..

Anyhow, thanks for clarifying my thinking.... Once I started comparing the two systems I realized that the boomkicker design should be adjustable, same as the rigid vang... just didn't see it right away.

So it looks like my major issue with the boomkicker has been resolved...... I'm especially pleased that Chris may be able to solve his problem easily and inexpensively by simply relocating the boom's bracket.

 

[sinnettc]

PO already shortened the rods. Longer or weaker would definitely help with the problem. Placement of the in-boom reefing lines dictates where the boom mount goes as the perfect spot would be right where the reefing lines come out of the boom. Solid vang one of these days will sovle the issue.

Joe, me too. Not much headroom in the cabin but a blast to sail.

 

[GorillaToast]

PO already shortened the rods. Longer or weaker would definitely help with the problem. Placement of the in-boom reefing lines dictates where the boom mount goes as the perfect spot would be right where the reefing lines come out of the boom. Solid vang one of these days will sovle the issue.

Joe, me too. Not much headroom in the cabin but a blast to sail.

On my Boomkicker, the attachment point at the mast base is variable, which will also change the geometry. Is yours all the way at the end of your sail slot? If not, try lowering it. On mine it's just a matter of unscrewing it, sliding it down and reinstalling the screws.

 

[Wanderer138]

Your boomkicker problem sounds like trying to sail without loosening the topping lift. It works against your primary sail trim controls. I also don't understand why the boomkicker failure caused the boom to drop into the cockpit. Once the mainsail is raised it should support the weight of the boom with no trouble.

I agree with everybody else; try sailing without the boomkicker for a while. It's only purpose is to support the boom when the mainsail is lowered and there are simpler, less-obtrusive ways to do that. Worse comes to worst, you can always reinstall the topping lift.

 

[sinnettc]

On my Boomkicker, the attachment point at the mast base is variable, which will also change the geometry. Is yours all the way at the end of your sail slot? If not, try lowering it. On mine it's just a matter of unscrewing it, sliding it down and reinstalling the screws.

Yeah, it's as low as I can get it and still attach the vang to the tabernacle padeye.

 

[sinnettc]

I also don't understand why the boomkicker failure caused the boom to drop into the cockpit. Once the mainsail is raised it should support the weight of the boom with no trouble.

Sail was down, we were heading in. I put some weight on it as I stepped into the cockpit and bang!

 

[bentwing60]

After following this thread for a while, I am amazed that after very good descriptions of the purpose of the various controls, no one has commented on the power available from the various controls. Just compare the line size and purchase on the vang versus the mainsheet and it is clear that if you want to pull down on the boom to windward, use the most powerful control. Vang is for finesse and offwind, mainsheet flattens the sail to windward and outhaul and cunningham control draft. Size matters. If your old sail won,t shape properly, it might be the old sail, not the controls.

 

[Stu Jackson]

The vang on our boat flattens the mainsail going upwind, too. The vang is NOT ONLY for downwind sailing.