Andy T found this article about building swing rigs on a rather pretty website. He though it was very difficult to read and had probably been typed by Angus until he realised it was in German and asked Angus.
Angus confimed that he hadn’t typed it and went off and translated it (but he made someone else do the typing) [Guess who:D]. And so here we have it.
Incidentally, Roger Stollery, the inventor of the swing rig has read it and approves. So let the rig wars commence.
Thank you Angus, for the translation and posting. Thanks also to the DSV and MBR. Nice work.
A salute to Roger Stollery who has brought the swing rig to the attention of modelers. I reckon that Roger “invented” the rig independantly. Thoughtful, creative people do that sort of thing. Unless Roger is about 100 years old he is not the first to use such a rig. Some really old time guys were at this long ago. I am thinking of the likes of Manfred Curry (incidentally a German person) who tinkered with the swing rig, on full sized boats, way back in time. These remarks are in no way intended to discredit Roger and others who have been so generous in sharing their discoveries.
Some time ago I had a conversation with the secretary of the US1M class. I asked him about the feasibility of a swing rig. He told me that those rigs are for light air only and that in moderate to heavy air downwind, the boats had a tendency to pitch pole. Has anyone had such an experience? I cannot think of any reason for this to be so. It seems to me that 600 square inches presented to the wind will generate a force X no matter how it is held aloft or no matter whether the mast swivels or is fixed. My boats have not had any such tendency. Maybe there is something to the claim based on the difference in what we Florida sailors call moderate wind as opposed to what Massachusetts sailors call moderate.
If there is any criticism for the swing rig it has to be that the mast is self supporting. As such the mast must be somewhat stiffer, thus heavier, than one that is held in place with shrouds and spreaders and things.
On weight of masts, I have been involved (more as an onlooker than anything else - the other peopole involved were infinitely better structural engineers than me) in structural calculations for some small ‘Freedom’ type rigs. We concluded that because of the absence of shrouds, spreaders, etc, and the much more exteme taper of the mast (no compressive loads to speak of) the unstayed cat rig was actually lighter AND had a lower centre of gravity than a conventionl 80% height fore-triangle sloop.
Certainly the mythology in Britain is that swing rigs are for ghosting conditions. It is certainly true that Stollery BUGs and ANTs are almost unbeatable in very light airs, or they were at Aylesbury. This could have had something to do with the fact that they were carryying huge rigs (inferior to the normal one in windspeeds over about 5 knots) specially made for the occasion.
The advatage does fade away as the wind gets stronger.
I must plead guilty and throw myself upon the mercy of the court. It seemed a good idea at the time because the Yahoo user group format is better able to store files for ready reference. I remember thinking that there were few typos and Angus must have been wearing his professional translator’s hat.
I have three two Bobs, three Bug 3s and an Ant. I find that swing rigs perform very well in all conditions and quote Birkenhead as an example, for the wind there was so strong on the first day that we all used the smallest rig. So too was the wind for the Hove Trophy not to mention the Toephy meeting at Guildford in the early Spring when conditions were severe. Sufficient I feel sure to dispel all myths that the swing rig works well only in light conditions. ( I had a sixth at Birkenhead and a fourth at Hove)
I am wondering whether it is more a matter of " Its not what you build, but the way that you build it " when talking about sail types.
The Swing Rig that Angus translated is a wonderful example of a simple looking, elegant and minimalist rig - but it still has about 8 different areas of possible adjustment and that’s after all the basic design parameters have been played with.
Brett’s McCormack rig has about 2.
As a relative beginner to this sailing lark I find that 2 possible adjustments is about all I can cope with, and identifying the effects of even those can be difficult. I don’t think Brett has ever claimed that the McCormack rig is the most efficient - but it does get you within striking distance of being competitive very quickly.
The likes of Roger Stollery and Charles Smith have probably got between them more than 60 years sailing experience ( the more uncharitable out there would say a lot more ) with the Jib and Main type of sail - be it traditional Bermudan or Roger’s Swing Rig. Consequently, what to adjust to gain what effect is second nature to them and it can all be quickly read across to a Footy size rig and to good effect.
Don’t get me wrong here, these comments are in no way a criticism of the Swing Rig as such - its just that I feel, for the raw beginner to sailing, of which Footydom has many, the McCormack rig is the logical way to go because :-
It is simple and cheap to make.
It is simple to adjust.
It automatically matches the Swing Rig advantage of throwing the Jib and the Main over opposite sides of the boat hence reducing helming problems.
It has the same lower sheet loads as the Swing Rig.
It has the unique wind dumping feature which means that coping with unexpected gusts is easier.
It is an ideal stepping off point into competitive sailing with a lower risk of being relegated to the back of the fleet because of a lack of specialist knowledge.
I would expect that item 5 might offend some of the traditionalists who would consider that learning this specialist knowledge is all part of sailing. This would be an unfair criticism, since I am sure that Roger in charge of my Mistralette and me in some kind if control of Roger’s rAnt would yield the same predictable result.
In the same vein, I seem to remember Graham Elliott a top IOM builder and skipper sailing a Footy for the first time at Colwyn Bay earlier this year - borrowed Bermuda rigged Micron. He was really complaining early on about poor handling. But he stuck with it and was constantly adjusting this and tweeking that until by mid-day he had gone quiet and was sailing competitively. Just another example of when you know what you are doing most things are possible - if that had been me, I would probably still been in the middle of the pond.
I thought a picture might be worth at least a few hundred words. Mast and fixed boom are 4mm, gaff and jib club are 3mm. Obviously the gaff can be eliminated completely if you go with a standard main as opposed to the fathead which I’m quickly becoming very attached to. You could keep it if you wanted and have it do duty as a mast crane.
Has anyone actually tried a swing or McRig with the mast step angled aft? I know it was mentioned some months back but I want to know if anyone has sailed a boat this way. I keep promising myself I’ll try it… “Eventually all great plans must degenerate into actual work.”
Thanks for the reply. I can see now my question could be misunderstood. I’m talking about a mast step that is tilted back from vertical i.e. the bottom of the mast step would be forward of the top. The Z bend wire going into it would be bent at an acute angle where it went into the mast step. The result would be a vertical mast while beating and the mast angled aft on a run.
Tilting the mast pivot might be helpful for windy conditions, but I suspect that in light airs, it would make things difficult on a run, since the sails would have to go “uphill”, fighting gravity in order to swing the boom out.
Hey Brent - I mentioned the aft raked mast tube a while back. I’ve also set up Brujo to test the system using a modified McRig. The jury is still out though, I had a messy sail and I didn’t bother to add a counterweight to the boom to help balance the rig. I think more attention to detail will fix a lot of the bugs. At that point I can decide if the system is worth the tinkering and if it can be made user friendly.
And Bill you are mistaken about gravity hindering the rig from going out. In fact, the gravitational pull on the mast not only swings it to a running position, thats where it wants to stay, making it hard to gybe because the mast has to travel uphill around the sloped pivot to get to the other tack. A McRig requires a counterweight at the end of the boom to retard this tendency. I think with a swing rig, with a jib and main, this swing out symptom may be less pronounced, but the mast will still be ahead of the pivot axis so it’s weight will still be a factor.
The raked mast tube is an interesting proposition. Here are some pros and cons.
Downwind the mast is raked aft moving the center of effort of the sail away from the bow. This should be similar in effect and mechanically simpler than Bill Hagerup’s sliding rig.
On reaches, with the rig let out from the beating position, the mast starts canting to windward.
Downwind the sail becomes more centered over the boat. When the sail is set up for a beat it looks like any other McRig. When the sail is all the way out, perpendicular to the fore and aft centerline, the raked pivot not only tilts the mast aft but to windward as well. On my set up the mast is almost vertical (viewed from directly astern) when the sail is let out. The 30/70 relationship of area around the pivot axis doesn’t change, so weathervane control isn’t effected.
Currently the mast weight governs too much of the sail’s action.
Rake angle of the mast tube may be the critical factor in determining wether this is a viable concept.
The mast tube location has to be farther forward than on a McRig with a vertical mast tube. Because the raked pivot is closer to parallel with the mast rake, to maintain the correct 30/70 area ratio the mast pivot has to be closer the mast. To keep the upwind center of effort in the same place it would be with a rig with a vertical pivot the mast tube has to move forward. This may negate any gains having the rig tilt aft might produce, although the taller the sail the more gain with aft rake.
Aft rake of the sail may also contribute to weather helm on reaches and runs. This is theoretical at this point. I had too many other concerns to notice this effect, but it may be lurking out there, particularly in freshening winds which is what I envisioned this rig to be for.
In light winds, with the rig out on a reach or run, the sail’s camber is in reverse due to gravity. This may adversely effect acceleration because the wind must first lift the sail’s weight before air flow can can be established.
Of course as I refine this system I will probably find a whole new set of bugs and gremlins to report, it the law of unforeseen consequences.
My initial investment of energy was minimal and I am working on some refinements that should give me a clearer picture of this system’s potential. At this point I wouldn’t recommend that anyone rip up their deck to install a raked mast tube. There are too many variables at this point for me to provide you guys with a even a starting point. I’ll keep you all posted on my progress.