swing rigs?

ok guys and gals
here is a question some might find intresting. i have never had a swing rigs boat. i dont think i have ever seen one in real life. can we discuss the benifts of the swing rig? has anybody got any pictures?
i dont know the benefits of a swing rig
cougar
long live the cup and cris dickson

Swing rigs are used extensively in the M class for various reasons. From a simplicity standpoint they are quick and easy to change, literally in 10 seconds. Once a rig is properly tuned the tune can be kept on the rig because it is not necessary to set everything up from scratch each time you sail. The only things to do are to tighten the (cunninghams) halyards to bring the rig into tune. The twist of the main and jib can be kept constant because the backstay stays tightened on or off the boat. The only thing to changing a rig is to step the rig in the mast tube hook on a single sheet tighten the halyards and you are off!. Upwind performance is similar to a conventional rig but downwind and reaching performance is superior in light air because the whole rig is working for you 100% of the time-The jib is permanantly winged out. Jibing the rig without loosing a lot of momentum can be tricky as can sailing in highly shifty air. Once you get to B rig conditions I would move back to a conventional rig because they don’t seem to nosedive as much as a swing rig. I like them because we sail in light air quite often so the performance downwind makes a big difference to me. I also like the fact that I can leave a rig change decision to the last second if we are in crossover conditions and if I botch the decision, I can change back within seconds.

I bought a Bantock Strad with a swing-rig on it to goof around with and see how they worked. I have had a chance to race against another Bantock Strad that has slightly more ballast and so far they have been even. I have not even begun to take the time to set the boat up to it’s potential, and practice with it and put in the time and effort to get the most out of it. Everyone tells me that they are significantly better for multiple reasons but all I have seen so far is that it is something you have to work to achieve… in other words… don’t expect it to jump out of the box and be instantly better… you are going to have to work for it to get the extra performance. Seems fair enough.[:-apple]

I tried to upload a pic of the boat but I keep getting kicked to UNABLE TO OPEN PAGE error.

Larry-I know what you mean about tuning it to its performance level. Many things from Bantock seem to be a little bit hard to get right BUT when they are they are very fast. The twist in both sails are critical to get “right”. When they are you will see the boat “jump”. I have an older Bantock B swing rig which hasnt seen alot of action because we sail in light air. It was dialed in probably 10 years ago and is still utilizing its original settings from then. It was very very fast for me in a recent regional championship race-I just set the halyards and was off.

If there is one area of performance that is totally missed and under-estimated (IMHO) it is nothing more than practicing with your boat and getting good with it. As with anything else… the learning curve at first is STEEP and the improvements are <u>tremendous</u>. Having a steady partner to work with/against is VITAL… and sadly something you cannot buy.

I feel bad that I never get the time to put into boats such as that… maybe someday when I get caught up HAHAHAH… how funny does that sound… One of these days… this is going to be a LOT of fun (again)[^]

G’day , I know a little about these swing rigs. I few started to come to our Marlhead club. Secondhand boats , some Stollery Roar Edges and other types. There was nobody around who knew much about them to help the novices get them going. Most sailor just threw their hands up and walked away. Anyway I asked around about them to a few people who ran these sort of rigs and did a few articles on tuning them. for the novice. some of the things we found was when they were tuned , the novice started appearing at the top of the fleet. for these boats are far superior but only in 1 to 10 knots. One has to have a wind guage with them to sail one of these boat because you have to change down in rig size earlier than a normal boat. You do have to think about , perhaps using a conventional rig in really stormy weather , from 15 to 25 knots , after that you prop up the bar.
The sheeting on the jib is critical, the luff on the jib is critcal( no sag) and one can tune their rig before it goes on the boat. And one other thing is (and I want you to think about this) you MUST BEND your sail to the mast and not like the conventional way of the mast to the sail. that should get you started. any questions?

Now you are started tuning your rig, the jib is to be tight on the foot of the sail or tighter than normal. The jib boom is to be out from the centreline of the boat about three finger thickness’. Try not to put too much tension in your back stay for you will only put tension in the whole rig. Some of these swing rig mains are double luff sails make sure that the sail move on your mast , if they don’t, fix it.

How far out do you sheet the main, i have a viper with a sting rig

Dennis , start with 10 deg off the centre line and go from there. S

Dennis , one of the big problems with swing rigs is that the skipper is going to have to learn to do it (sail) diferently. Possibly the first thing to tell you is to learn how to sail with both hands on the transmitter and use a combination of winch and rudder to work the boat. If you don’t get it first go, perservere for in the end it is worth the effort.

Dennis do you have a Viper “M” or a 10 Rater

<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”>Originally posted by hoj

Dennis do you have a Viper “M” or a 10 Rater
<hr height=“1” noshade id=“quote”></blockquote id=“quote”></font id=“quote”> Yes i have the viper + marblehead. I sail in southern california we get very light winds out here.Steve i sheet my main out about 5% off the center line,about how much camber do you put in the main,i know you said you have the jib tight.Also my viper+ has 8" of bend in the mast.

Dennis, what I said was that the jib should be ‘tighter’ than you you would run a normal jib on a normal M. I know that it is easy to get the wrong ideas on Emails.

Do you mean that you have got a 8" bend in your mast , between the foot of your mast and the top of your mast? How does the boat like that? Will it point? Is the boat stalling, or is it pointing extra well and going?

For putting a bend in it, you are in effect moving your sail area Centre of Effort back past your C of B and C of lateral resistance. and you start to do something with the boat , that the designer didn’t want. But it is all about ‘sucking it and seeing’ with swing rigs. also keep in mind that main sails don’t like to rotating around bending masts but if yours is working then…

http://www.magicksails.com/KiwiSails19.html

Just to help Dennis out. I noticed a while back that Blackmagick has a Sting rig image on its website. So you can see the Sting rig with all that mast bend.

As I remember it, the reason Bob Sterne put all of that bend in the mast is so he could use a big jib while still allowing the swing rig main to rotate the mast - CE far enough aft versus the mast pivot point. Normally swing rigs have to use a small jib in order to keep the CE aft of the pivot point. I think that is right anyway.

Scott

Question - one of those “…in my mind” type of ones, if you don’t mind?

If one bends the mast (prebend or just a lot of backstay), you are in reality “pulling” the center section of the mainsail forward. How is it then that the Center of Effort moves backwards? Everytime I prebend, my CE moves "forward for the majority of the main, weather helm goes away and I get more neutral, or maybe even a bit of lee helm? (in addition to depowering as well)

See sketch - with that much (exagerated) sail area moving forward, how does CE move backwards?
What am I missing?

Download Attachment: [ Mast bend.JPG](http://www.rcsailing.net/forum1/data/Dick Lemke/2005228124237_Mast bend.JPG)
13KB

Dick,

In addition to the effect you describe in your figure, adding more backstay reduces headstay sag. This means that the mast is usually raked further aft. You might not notice it on shore, but when you are out sailing, the loads on the jib cause the headstay to sag and this pulls the rig forward. By adding tension to the backstay, you reduce that sag (which has other benefits to the headsail shape). Thus, your rig is reaked further aft and your CE moves aft.

  • Will

Will Gorgen

Hi Will -
I can see your illustration with a full forestay and jib to top of mast/crane. Usually, headstay sag on a fractional rig (as in photo) is controlled less by backstay than sidestay (or running backstays). Consider on a fractional rig, the possibility of the forestay attachment point part way up the mast and moving forward as mast bends forward and backstay tension is increased. Wouldn’t a fractional rig induce “more” forestay sag as mast is bent?

In the case of boats with no backstay, pre-bend is created with diamond tension - and mast is prebent without easy way of tensioning forestay any further. - but OK - if you say so ! [;)] [;)]

Hi Steve,Yes i have to bend my mast 8" Bob Sterne the designer of the viper cuts the main luff with 8" of curve,so you have to bend the mast to match, he calls it a elliptical main.If you read the reply from Scott Vernon and pull up the web site you will see a picture of the viper with all 8" of mast bend.It’s a very fast boat when set up right,going down wind it’s hard to keep up with it. When the wind come up over 6mph she gets over powered and have to change to B rig, she still a fast with this rig

My 10 R has 10" of bend. After bending the mast 10" from vertical the sail is attached and matches the mast perfectly. The luff of the main is curved and the leech if straight and vertical. I think I have the first and only 10R stingrig from Sterne. With all that pressure my crane was cutting right through the carbon mast slowly. Lucky it didn’t all go at one time it would have torn the sail in half. Now as I remember I hadn’t put the sail on and it was sitting for a couple of days.I put whipping where the crane was cutting through and also put some wood inside and epoxied everthing together instead of CA glue like the instructions. It has been fine since but it is still scary to look at all that bend and pressure that can’t be released. It is the fastest monohull at our pond. I set the main and jib at 5 and 15 just like a regular sail. Actually I set everything about the same and sail it the same. Everyone here loves to sail it. They have no problems. It just looks a little wierd. I have been making swingrigs for 20 years but this is better than any I have made. The mast is bent so much you can add any amount of forestay pressure you need and not change the mast any. The teflon bearings make it rotate very easily. I ordered an extra hull tube for the mast and plan to put it in one of my tri’s (Superslim).

Dennis , that was interesting what you said about Bob Sternes boat about when the wind gets to about 6 knots he has to change down. We recommend to our blokes who run these rigs to carry a good wind guage with them to judge the 6 knots etc. I don’t know what a viper is , I’ve just had some experience with some Roar Edges and as I said we had to help some novices out. Glad to see some of the real experts here.