Swing Rig - What's all about?

[D'ARTOIS]

This evening, I visited the Van de Stadt Design pages on the internet and found this: the Swing Rig. Apparently an easier way to sail, combined wit a free standing mast. (Carbon)
It is not said that it is designed for racing, nor that any solid numbers are given regarding speed etc. Only that it eases handling and that it powers the boat on broad reaches like main and spi together.
What's the idea?

[Andy P]

looks like a big moth sail!

There have been many similar single sail boats eg catboats, and sandbaggers in USA .
Drawback is balance when pushed hard = heel = weather helm
modern boats eg Freedom 25 ( but this had kite also ) and other freedom yachts

in the 70's in quarter ton cup there was a rule buster FRA boat called ' L'Effraie ' or someting similar that had the mast right fwd, with jumper struts and shrouds to hold the flexy mast up.- no jib or kite.

[casavecchia]

Hi D'ARTOIS,
Have a look at my thread "canting mast". Having used such a mast during the last eight years on small dinghys(monohulls and trimarans) I can state that there are definite advantages. May be not so great but worth the small complication of building a kinked mast.
Easyer jibes seem a good argument for a cruising boat too.
Marco.

[D'ARTOIS]

Hi Casavecchia,
Van de Stadt claims that this catrig handles easier, and that it gives a sort of performance more or less comparable to main and spi - ?
If you have a good look at the boat, you see that it is more or less a racing design.
What I would like to know is, - there are many catboats in the US f.e. - how do you rate such a rig. Gives it more speed than the usual masthead sloop rig?
Here in this part of Europe, those catrigs are hardly in use, save for some small design classes.

[jocki]

hi all,
i would like to pick up your conversation about canting riggs , as i am designing a modelboat and am considering to put a canting rigg on it as the rules do not allow canting foils...
alternativley i ll step a swing rigg,so if anyone has some good ideas-would be great.
cheers

[D'ARTOIS]

Hello, Eric Sponberg is the expert in this field, he has designed a two-mast fast cruiser with free standing masts; I rate this as a very attractive design since it leaves options - the single sail design of Van de Stad does not.
So I was wondering if I could hear some comments on this configuration........
apparently nobody finds it an attractive topic so it's actually dead for the moment........your turn now.....

[John Perry]

Originally Posted by casavecchia

Hi D'ARTOIS,
Have a look at my thread "canting mast". Having used such a mast during the last eight years on small dinghys(monohulls and trimarans) I can state that there are definite advantages. May be not so great but worth the small complication of building a kinked mast.
Easyer jibes seem a good argument for a cruising boat too.
Marco.

Van de Stadt are claiming a patent for this kinked mast but their patent is invalid since I made one fifteen years ago. For all I know other people have made them too. Here is a picture of the lower end of my mast showing the kink. This mast is made from carbon fibre, as is the Van de Stadt one. You can also see in the picture the inner sleeves of the two bearings which allow the mast to freely rotate in a socket which is bonded into the hull structure. This socket extends a little above deck level to give more spacing between the two bearings. The picture also shows the bracket built onto the side of the mast onto which the tack of the mainsail is attached. This bracket is shaped to drop down the outside of the socket in which the mast rotates so as to hold the tack of the sail just above deck level.

I have found this rig works well and the kink in the mast gives very light sheet loads so that one can quickly control the sail force with a single part sheet, rather as one does with a windsurfer sail. The light sheet load was the main reason I used this design but it is true that it does also have the effect of canting the rig slightly to windward, although on my boat, which is a bi-foil sailing hydrofoi,l I actually cant the rig a lot further to windward by heeling the whole boat to windward, thus gaining a leeway resisting force component from the lifting hydrofoils.

John

[D'ARTOIS]

Thanks for your reply, at east I understand the technics behind the design, nontheless what still puzzles me is the simplicity of the single sail. My last boat, used to fly 8 sails and I could set sail as weatherconditions allowed it making my 9/10 knots almost at a constant. One time I clocked 14 knots when there was a brutal wind and under main, stay, fisherman and jib no 4 I got her that fast.
It was a bit scary too.

Now I see this single sail, nothing to influence speed - except for setting a kite maybe? How does this feel?

[casavecchia]

Hi John,
so strange Van de Stadt though of patenting an idea that has been used so widely, in Australia on a model boat, in Italy on at least 4 / 5 boats, in England by you and
who knows how many times elsewere.
Should this mean that we cannot build kinked masts anymore?
Best regards.
Marco.

[mattotoole]

Originally Posted by casavecchia

Hi D'ARTOIS,
Have a look at my thread "canting mast". Having used such a mast during the last eight years on small dinghys(monohulls and trimarans) I can state that there are definite advantages. May be not so great but worth the small complication of building a kinked mast.
Easyer jibes seem a good argument for a cruising boat too.
Marco.

Easier jibes indeed! I don't think the kinked mast is going to help. That's still a big sail.

I've always wondered if balance downwind becomes a problem with big catboats. I've deathrolled a Laser way too many times!

Hey, howzabout a single cat rig upwind, and one of those newfangled kites downwind?

One thing is certain: you don't have any idea what exactly van de stadt patented unless you get a copy of their patent; it may be some technical manner in which the rig is supported ect. but it's highly unlikely to be the kinked mast.
Just because an individual built a working prototype of something doesn't necessarily invalidate a patent later on the same thing IF the original wasn't published.
As to the kinked/canting mast I know for a fact that that was published in the late 70's or early 80's in an English mag called "Radio Sailing" in the form of an ad for the "Mickey Finn" an rc catboat that used the kinked mast to reduce the sheet loads on the sailwinch....
But ,again, that is probably not what van de stadt actually patented even though they may want you to think it is.....

[CT 249]

A kinked mast was published mid '60s in one of the winning designs for "Yachting World" magazine's contest for the IYRU/ISAF trials for a new singlehander - the trials that created the Contender.

[casavecchia]

Thanks Doug,
I think you are right, there are for sure other features involved, such as mast-boom connection.But this doesnt answer my question: do you think I can still build my kinked mast?
And yes Mattotoole , I think that a canting mast like this offers definite advantages.
In a conversation I had with Mr Bruce Kirby many years ago he told me that he worked on a similar device on a Laser, based I think on two discs with offset holes for the mast, one at heel and one at partners.
He too admitted he found advantages though may be offset by the complication of the system. This system permitted adjustment of rake independently from the canting function.
This is what I seem to remember as so much time has passed by.
Marco.

[casavecchia]

Interestingly the Brazilian jangadas use a very clever low tech canting system. They have one hole at partners and three holes on an athwarship line at heel.
When tacking the sailors unstep the mast at heel only and drop it in the leeward hole thus canting the mast to windward.
Marco.

Marco, I don't think you have any problems whatsoever regarding using the kinked mast.
If you were going to produce it I would pay for a patent searh-not to patent it but to find out what -if anything- related to it may be patented. Its possible that van de stadt may have published their patent number someplace or would tell you the number. A patent that has been granted is public information.