Inducing Twist

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Mar 23, 2004
119
- - Paradise, CA
Hi Don, Basically my post deals with hardware to induce twist. I posted this originally on the Smaller Boats forum but didn't get a lot of hits so I hoped you would comment. Here's how this started: Last weekend I was sailing in light winds (3-5 mph) in my Hunter 216. My top batten on my main, which goes from the leech to the luff, was too tight so the draft on the upper part of the sail was too deep. I tried adjusting the batten once but couldn't seem to get it loose enough. I was sailing close hauled and the groove felt good. But, the top of the main was stalling. The top batten was not parallel to the boom and I had no twist at all as expected. I figured if I could induce a little twist the sail might fly better. I pushed up on the boom and got a pretty good sail shape and the top of the main quit stalling. The H216 has an open foot main and I had about a 9-10% draft of the lower part of the main and the bulk of the sail seemed to be working pretty well (I haven't installed telltales on the middle of the main yet but the leech telltales were flying well and I wasn't pointing too high). The H216 is relatively tender and I got to thinking about inducing a bunch of twist when the wind kicks up in lieu of reefing (I'm one of those that reef way early normally but this is sometimes not the thing to do in the middle of the race). After googling the subject, there seems to be three choices, the topping lift, a boom kicker or a rigid vang. Topping lift - Googling gave some hits that imply that many sailors use the topping lift to increase twist...actually I find this hard to believe but maybe it is done. Using the topping lift for this purpose doesn't seem like a good idea to me for a couple reasons, 1) it could be nasty if it broke under the load and 2) I have a fractional rig and I'm not fond of the load I would put on the upper section of the mast above the top shroud/fore stay tangs. I admit to being green enough that I don't know if topping lifts are actually used for this purpose. Further, the topping lift would have to be to the weather side and it would be difficult to switch from one side to another. Boom kicker - I suspect these do not have enough "kick" to overcome the main sheet tension when close hauled. Rigid vang - Been looking at the Garhauer (as it is the only one I can afford!) Will this have enough "up" force with the in-build springs to induce the twist I want? This could be a nice choice for me as the 8:1 vang that came with my boat is inadequate. Any advice would be greatly appreciated.
 
May 17, 2004
2,111
Other Catalina 30 Tucson, AZ
Ranger Paul: There are a couple of things to talk about in your message. I'll deal with the main gist first. I can make your choice very simple. First of all, the 2 mainsail sail trim controls for twist are the boom vang and the mainsheet. The primary purpose of the topping lift is to hold up the boom when the sail is flaked. In very light wind, it can be used to put a small bit of belly in the sail but that is it. The topping lift is not a sail trim control. I don't know a lot about boom kickers but I do know a lot about the Garhauer Rigid Vang, having sold and install a bunch of them. There is no "up force" force on their vang. Hydraulic vangs, which are very expensive, do generate an up force. With the Garhauer Rigid Vang, the boom is just sitting on the springs and as you crank on the boom you are pulling down the boom. When you release the vang, the boom goes back to its normal position, whatever that happens to be. The trick is determing the "normal" position. In my case, the normal at rest position I selected was about 10 degrees above horizontal so that is how I installed it. So, when I raise the mainsail the boom is now 10 degrees above horizontal, which is just about right for light air on my boat and I then merely crank down from there for whatever setting is necessary for the point of sail and wind conditions I'm sailing in. In very light and light winds, you want the sail pretty flat and the reason is quit simple. The wind does not have enough force to get around a sail with a lot of draft depth(belly). That effort of the wind getting around the sail is what produces the power to make the boat go forward. Without that force, you just sit there. I've been in many very light air races and I see a lot of races bellying out the sail in hopes of catching what little wind there is. On the other hand, I shape the sail flat and glide by them. Most of them never get what I'm doing. Some ask me later how I did it and I tell them - clean bottom!!
 
Mar 23, 2004
119
- - Paradise, CA
Garhauer Rigid Vang

Don, Thanks for the info about inducing twist. If the Garhauer rigid vang does not provide "up force", why would I spend $2.5 boat dollars to get one? That is, what is the advantage over a topping lift and a normal boom vang? Also, I trailer my H216...if I got the Garhauer, what additional hardware might I need to easily install/remove the Garhauer when I set up/knock down the boat?
 
May 17, 2004
2,111
Other Catalina 30 Tucson, AZ
Garhauer Rigid Vang

Ranger Paul: A soft vang does not provide any up force either. I can tell you why I purchased the Garhauer Rigid Vang (I got it at cost -no, no I'm just kidding!!). A solid vang gives you more stability over the soft vang on all points of sail. Additionally, there is no bounce from the boom that you get with a soft vang and I was also able to eliminate the the topping lift. I'm a sort of purist and I hated looking at that topping line flopping all over the place and hitting the leech of the sail. It disturbed my karma. The topping lift is NOT a sail trim control. Its main use is to hold up the boom when the sail is flaked. I'm not sure how you are using the topping lift (how much your pulling the boom up on various points of sail) but your using the wrong devise to shape your sail from a sail trim standpoint. What you are doing is converting the topping lift into a quasi rigid vang and your using 2 control (soft vang / topping lift) whereas with a rigid vang you could use only one. Most mates don't use all the mainsail sail trim controls anyway and your now adding another one to deal with, but my thought is if your happy with what your doing and get the results you want then sail on and save the $250 or whatever the cost for the Garhauer is. Additionally, if you are cranking up on the topping lift over 10 degrees above horizontal your going to far. As I explained, when you mount the solid vang, you install it 10 degrees above horizontal and your there for light air situations. The Garhauer vang is bolted to the boom by means of a boom plate and to the bottom of the mast by a mast plate. To disassemble it, all you would do is pull a pin on the mast plate and that would be it. You could then secure the arm to the boom and store it as part of the boom.
 
D

Denis

About this.....

Don, I read your statement about the toping lift not being a sail control, and I would like for you to tell me where my reasoning is flawed in the following scenario: I do not have a traveler on my boat. What I do is set the boom height to whatever angle is needed to provide the right amount of twist for the conditions, by adjusting the toping lift and the boom vang together. By doing this the boom can no longer move up or down. Now when I crank on the mainsheet,or release it, I only affect the angle of attack, without altering twist. I realize that a rigid boom vang would be an easier alternative, but I am just curious to know if my assumptions are incorrect. Thanks for all your great explanations in previous posts. Denis
 
S

Scott

Do you have an adjustable back stay?

I'm certainly not going to answer for Don and I think I would like to hear an answer to set my head straight. From my experience as a windsurfer, the way to trim for higher wind is to "loosen" the leach by increasing downhaul to create more bend in the mast. A little exra outhaul also flattens the shape. All of this moves the CE back slightly. Would tightening the backstay have the same effect and can the outhaul affect the draft at the top of the mainsail? Does your boat have an adjustable backstay or could it be added?
 
May 17, 2004
2,111
Other Catalina 30 Tucson, AZ
About this.

Denis: What you are doing and what Ranger Paul is doing is fine as you are making due with what you have. The most important part about what you are doing is that "you know what you are doing" and that is everything. Every adjustment has to be made wih a particular result in mind. How you get there is not important. The problems arise when mates guess at what they are doing and in 9 cases out of 10 they end up working against themselves. The adjustments they make are like throwing a sports car in second and flooring it and then pulling up on the emergancy brake!! If the sails could talk they would ask the trimmer what in God's name are you doing to me.
 
May 17, 2004
2,111
Other Catalina 30 Tucson, AZ
Adjustable back stay

Here's the skinny on an adjustable back stay. Most masts can't be bent like on a J boat for example. Bend you index finger and you'll see what a bent mast looks like. Most production boat masts are too stiff. You'd have better luck trying to bend a telephone pole. What generally happens is you end up raking the mast back and now you have forestay situations to contend with - every action has a reaction. I have a split backstay adjuster and sometime I use it when I'm bored and want to yang on something. To me, it is the last sail trim control I mess with. The other mainsail trim controls are much more important. I know I'll hear from mates who swear by raking the mast and I just say fair winds and if it works for you go for it. The real reason a mast is bent (not raked) is to take fullness out of the middle of the sail and make it flatter. Go back to the bending of the index finger and you'll see what I'm talking about. Raking the mast has no effect on fullness. On the outhaul - it is used to induce or reduce the draft depth (belly) of the sail. It is also one of the controls for adjusting draft position. It primarily controls the bottom 2/3 of the sail. Here's a situation I run into all the time on middle to back of the pack race boats. The skipper will say to adjust the outhaul. He does not say which way or how much. If I'm invited on the boat to observe, I always ask what effect are you looking for. Some answers I get back don't make much sense but after I explain the function of outhaul the skipper usuallys gets the idea. So after we do that, my next question is now what are you going to due about the top 1/3 of the sail. That generally results in a blank stare but with a second or two of explantion, the skipper know what adjustment to make to get the whole sail in phase. As I've said before, knowing what result you are looking for and how to get it is EVERYTHING!! The goal in sail trim is to take the guess work out of mainsail and jib adjustment. My book The sail Trim Users Guide will get you to that point. You will know more about how these sail trim ontrols for the main and jib work than 75% of the sailors worldwide. Ask some of these guys who have read it. After you read the book, ask your dock neigbor to explain the difference between say draft position and draft depth and see the answers you get back. I guarantee you'll be smiling to yourself because you'll know the difference.
 
May 17, 2004
2,111
Other Catalina 30 Tucson, AZ
Adjustable back stay

Here's the skinny on an adjustable back stay. Most masts can't be bent like on a J boat for example. Bend you index finger and you'll see what a bent mast looks like. Most production boat masts are too stiff. You'd have better luck trying to bend a telephone pole. What generally happens is you end up raking the mast back and now you have forestay situations to contend with - every action has a reaction. I have a split backstay adjuster and sometime I use it when I'm bored and want to yang on something. To me, it is the last sail trim control I mess with. The other mainsail trim controls are much more important. I know I'll hear from mates who swear by raking the mast and I just say fair winds and if it works for you go for it. The real reason a mast is bent (not raked) is to take fullness out of the middle of the sail and make it flatter. Go back to the bending of the index finger and you'll see what I'm talking about. Raking the mast has no effect on fullness. On the outhaul - it is used to induce or reduce the draft depth (belly) of the sail. It is also one of the controls for adjusting draft position. It primarily controls the bottom 2/3 of the sail. Here's a situation I run into all the time on middle to back of the pack race boats. The skipper will say to adjust the outhaul. He does not say which way or how much. If I'm invited on the boat to observe, I always ask what effect are you looking for. Some answers I get back don't make much sense but after I explain the function of outhaul the skipper usuallys gets the idea. So after we do that, my next question is now what are you going to due about the top 1/3 of the sail. That generally results in a blank stare but with a second or two of explantion, the skipper know what adjustment to make to get the whole sail in phase. As I've said before, knowing what result you are looking for and how to get it is EVERYTHING!! The goal in sail trim is to take the guess work out of mainsail and jib adjustment. My book The sail Trim Users Guide will get you to that point. You will know more about how these sail trim ontrols for the main and jib work than 75% of the sailors worldwide. Ask some of these guys who have read it. After you read the book, ask your dock neigbor to explain the difference between say draft position and draft depth and see the answers you get back. I guarantee you'll be smiling to yourself because you'll know the difference.
 
Mar 23, 2004
119
- - Paradise, CA
Rigid Vang vs Topping Lift

Don, Thanks for all you comments. FYI: I do not use the topping lift as a twist control device. I heard that others were doing this and I wanted your input...it just seemed dead wrong to me. I hate the topping lift flopping around also. I cured this by adding a snap shackle where the topping lift attaches to the boom. Once I have my sail raised, I usually unsnap the topping lift and secure it to the mast. I lake sail with few waves so boom bounce is not really an issue for me. But, I think I yearn for a rigid vang because it is a cool device and the other sailors in my club will drool! More importantly, my soft vang is 8:1 which is inadequate for my boat while the Garhauer is 12:1 (I think). By the time I upgrade my soft vang to the power I need, it is only a small step more to a rigid vang. Christmas is coming! FYI: There are few sail controls on the H216, I believe by design on Hunter's part and their concept of the use of the boat. Mast bend and rake is pretty much fixed if one flies the spinnaker like I do. It is a reasonably big spinnaker attached quite a distance above the top shroud tangs on a fractional rig without a backstay. To fly it without bending/breaking the mast, the outer shrouds are cinched down pretty tightly and the rake setting recommendation is the "stern most" position. This bends the mast enough to handle the spinnaker stresses. But, mast bend and rake is fixed. This only leaves the mainsheet for angle of attach and twist control, the outhaul on the open foot main for draft control on the bulk of the main, the cunningham/main halyard for draft position on the bulk of the main, the top full length batten which defines the draft and draft position on the upper portion of the main (which, of course, is difficult to adjust once underway), and the vang for twist control. There is an optional traveler for the boat that is the ugliest thing you have ever seen and destroys the massively open cockpit...plus the point of attachment of the mainsheet to the cockpit sole and the boom without the traveler makes the geometry such that the addition of a traveler really doesn't add much. The jib has a fixed position jib block (my cuddy cabin now has a bunch of holes in it where I have fiddled the jib block position!). But, I love the boat. I am still competitive in my club races against Thistles, etc., yet it is comfortable and cruises great with me controlling everything while my sickly wife basks in the sun laying on the bench seat.
 
T

Ted

Boom Kicker

I use a Boom Kicker on a C&C 29. The product is bullet proof and inexpensive. The design of the Boom Kicker is very simple and each product is supplied with a couple of different stiffnesses of fiberglass rods which are used to provide the up lift. It provides plenty of up force and works nicely to induce twist in the main. It can be removed fairly easily which will come in handy if you trailer your boat on a regular basis. It has a nice high tech look too.
 
B

Bob

Thoughts

When Don says there is no "up" force on the rigid vang, he means that once it is installed, with all other controls eased, it can not be raised any further. However, you control how it is installed, so that you can indeed allow it to "raise" the boom when you want it to (more than 10 degrees, if you desire). Typically, this would be when reaching in very light air - in this situation, the weight of the boom can be detrimental to sail shape, as it does not let the sail form its optimal curve. Though this is well known among experienced sailors, I stumbled across the concept one night when ghosting along beside a buddy whose boat has virtually the same performance as mine. We were dead even for quite a ways, when I began messing with various controls. The biggest change occurred when I lifted the boom and took its weight off the sail - suddenly my boat began to inch ahead of his as the sail assumed a more efficient shape. When I let go of the boom, we continued at the same interval until I raised it a little again and once again pulled ahead. So yes, "raising" the boom by easing the vang tension can be an effective, if seldom used, technique. The Garhauer unit is so strong you can lean down on the boom if you want - the vang will give a little, but the spring is pretty strong. Yes, it looks good and kind of racy, but if you buy one do it for what it will give you in boat performance. Its only drawback is that there is not much "feel" - because of the spring pressure, when you tension it you aren't just feeling the resistance of the sail, so you have to judge by eye, not touch, how much is enough. By the way, if your jib sheets are running through a block that is in a fixed position, you are giving up LOTS more performance than a different vang will provide. Get some track and slides and you will be amazed at the variation in shape and performance you can create in the jib on different points of sail. Also, I believe that the top battens in most mains are too stiff - consider using material that is more flexible than what you have and see if it shapes any better. Finally, you are right saying that a traveler constricts cockpit space, but I'd love to compete against you in an identical boat that had a good traveler - you might change your mind about that modification.
 
A

Anchor Down

A Review of Class Notes

This thread is very entertaining. Let's review a little history, straigten out some of the scientific concepts, and agree on good seamanship. Traditionally, keeping the boom out of the cockpit was the job of the BOOM GALLOWS, a solid horizontal piece of wood mounted on an arch, with recesses to receive and secure an unused boom. it is not a sail control, but had other functions than supporting the boom, like providing a solid support to lean against when using a sextant. The boom gallows was replaced by the TOPPING LIFT. On racing boats, this reduced clutter and weight on the deck. It soom became popular on non-racing boats. THE TOPPING LIFT IS NOT A SAIL CONTROL. The BOOM VANG prevents boom lift as the mainsheet is eased for off-wind courses, and IS a sail control. A solid boom vang is the normal vang combined with a spring (or gas ram). This second component (the spring) is what supports the boom, and makes the topping lift unnecessary. The solid vang can be installed so as to cause the boom to rest a few degrees above the horizontal when the vang (the rigging part) is completely eased and the spring is loaded with the weight of the boom. This arrangement allows the sail to belly out a bit without the weight of the boom pulling down on it, providing a more desireable shape for light air. A BOOM KICKER is a spring that is a replacement for a topping lift only. It also can be installed/adjusted to support the mast above the horizontal when vang tension is released. The original boom vang is left in place. Using a solid vang or a Book Kicker to support the boom above the horizontal to create an advantage in light air seems to be one of their inherent side-benefits, and I don't know of anyone who would shake his head at using it this way. Using a snugged topping lift to raise the boom and induce a more rounded sail shape to match light air can be effective in light air, and most of us would find it acceptable, (considering the low forces involved, the TL is not doing much more than it does at the dock) but one should have a thorough knowledge of how the sail controls work before adding this small "CHEAT." Once the wind increases to a force that will overcome the weight of the boom and draw the sail out, continued use of the topping lift as a sail control is unseamanlike, and the sailor is better off reverting to the traditional sail controls. Regular use of the topping lift as a sail-shaping control reveals an ignorance of the effective use of the main sail controls: traveler/mainsheet, boom vang, clew outhaul, etc.
 
B

Bob

Well said, AD,

and I would add that leaving the topping lift tensioned in any way would cause additional problems when the boat is tacked or gybed. So if you do use it to get the boom's weight off the sail on a reach, remember to slack it off before doing anything dramatic.
 
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