I tried to make a mockup of the the goosneck for a Footy rig. Bending a small loop on the end was somewhat easy, and there’s an elbow where the mainboom attaches.
The problem I found was that you can’t use 1/16 wire for the gooseneck and the loop for the vang line because the bend at the elbow has no (or very little) flibility to let the main boom go up & down.
I decided to use two split pins on the mast, and one in the end of the boom. I’ll put some kind of tube or pin through the three split pins to hold it all together.
For the vang, I will have to use a split pin below the gooseneck (about 10mm or so) and either a split pin or a hole or notch in the mast to hook the vang line onto.
Are there any good photos I could study?
Here is how I make my goosenecks:
I don’t like to put holes in carbon fiber for one thing, weakens it. So, to start, I take a piece of 3/32" rod and flatten the end and then drill a small hole in it. I, then, take a section of tubing that will fit over the mast and soft solder an 1/8" tubing to it. Pass your 3/32" rod thru the 1/8" tube and bend it to the angle that you want your boom to be. With carbon tubing I have had to use some brass tubing inside the boom to match up the diameters so that the boom stays in the center. I have been making my own brass vangs, but this boat does not have one yet. My other footy is on display at the local hobby shop right now, so I can’t take a picture of it.
I usually just plug the end with some epoxy.
If you use 1/8" tube for a 1/16" rod, isn’t that too loose?
Sorry, I was sitting at my workbench and suddenly realized that I had put the wrong sizes in and hoped that I was going to get back before ya realized it:mad: Ah well, I did mean 3/32" rod which makes a good fit into 1/8" tubing, especially brazing rod as it is .089 dia. Now the info is right, sorry
still, with a elbow in a rigid rod like .089, how do you get any up & down movement of the boom?
Frankly, I have got as much flex as I care to have! Actually, if you look at Brett’s rig drawing, you will see that what I did is just an adaptation of his gooseneck. I simply created a way not to have to drill into the mast. Not sure why you would want a lot of movement, I would prefer to keep my luff tight anyway. You tie the tack at the gooseneck and pull up on your main halyard till it is tight and that would take all the movement out of it anyway. The looser, up and down wise, your gooseneck is the more you would have to pull up on the halyard. When it comes to the vang, you are trying to take out bending of the boom and it has nothing to do with the gooseneck except that it is attached to it for an anchoring point. I might be wrong, but it is just how I see it.
My version, using carbon fibre tow wrapped around a carbon tube containing a stainless rivet with the end threaded and fitted with a small nut.
Tamiya steering ball joint for movement on top, servo arm cut off as bottom piece. Cord vang with bowsie. Works great, no binding.
YUK…looks a bit rough up close with the macro lens…looks better in the real world.
I use something like that method on my 1m, but a tube first filled with epoxy, then drilled for the axle. Two steering couplers with a threaded rod for the vang.
Let’s see if I can just scale things down for my footy(ies).
I’m not much of a fan of string based vangs so I built this version. I have used this same setup on other classes of boats as well, just changing the length of the various tubes to suit as well as using different sized tub for the piece that goes over the mast. It is accurate and strong and the vang bit is precise and infinitely adjustable.
For an effective gooseneck, that is simple, uncomplicated and “inexpensive” I continue to use two interlinked screw-eyes. The one attached to the mast is vertical, the one attached to the boom is horizontal. Together they make it possible for the boom to raise or lower at the clew-end (sail twist), and swing from side to side and be adjusted by the main sheet.
Some have said there is too much friction, however using simple math and physics, it still represent only one point of tangent contact between each of the screw eyes, since each screw eye at point of contact is a round diameter, and we all know from basic geometry, two tangent circles can only have one point where they touch - unlike a bunch of ball bearings, pins and tubes, or steering ball joints from model cars. I realize it doesn’t “look” hi-tech, but it works.
I agree with Dick, that the screw eyes have ‘no friction.’ The reason for that is that there is no sliding! it’s just a point of contact (in tension) so friction really doesn’t have an effect.
how does your design allow for up & down movement of the boom? If that screw on the (bent metal thing) on the boom is tight, then there should be no way to allow for up & down movement.
It doesn’t. This method holds the boom angle constant, a desireable feature (I am told) on all my other boats.
I agree with the goal, but I don’t think your system will do it. It appears that with the screw on the end tight, it will hold the boom at the same angle regardless of the length of the threaded part. that bent metal part needs to be changed to some kind of swivel so the boom can move up & down relative to the deck and the threaded part.
From the graphic below, you can see that the vang angles A& B are different with the booms n Positions A&B, although the angles are a little exaggerated. The vang at that point on the boom needs to be flexible.
The whole point of having a boom vang is to prevent the boom from moving up in an uncontrolled manner. Otherwise you have no way to tension the leach of the sail as a means of controlling twist of the mainsail. It appears that Barry’s arrangement will work just fine…
I don’t think you see the point. The end of the vang at the boom is fixed with a screw on a rigid bracket. If the screw on that end is run in tight, then there is NO way to allow for any up & down movement at all! Not even controlled, like a vang is supposed to. Barry’s design will not allow for tension or compression. It’s FIXED at the boom end! the screw on that end would have to be loose, and then the boom would be sloppy. the vang tube would bow if you extended it.
Try this: put a long screw through a piece of sheet metal. Now run a nut on the screw- TIGHT. now see if that screw will flex in any direction. It won’t! Barely any movement if any at all.
Sorry, I think it’s the other way around. You’re the one who doesn’t get it.
Vangs work by forming a rigid triangle that restricts vertical movement of the boom. Barry’s arrangement forms a (somehat truncated) triangle which will have no need to be routinely moving up or down. For the very small amount of angular change needed during adjustment, it appears that the white plastic threaded tube will easily accomodate this as it is tightened back towards the bracket. Tension will be created by tightening the clew connection.
Dan or Brett, help me out here please!!
Where do you get the white plastic tube? Is it already threaded, or do you force thread it with the threaded rod?
Use of a traveller in conjunction with boom end sheeting will also serve a similar purpose. Circular travellers, with fixed sheeting allow the boom to swing to leeward, yet the fixed mainsheet provides tension on the leech of the sail. Once the traveller is let out from near the middle of the boat, as the mainsheet is eased, the main will develop twist - either for more power or to “dump wind.” While this will work well with a multihull and a wide beam - it can also work on a reduced sail - and I believe a few of the guys in the AC Class use the traveller idea.
As far as traveller control - it can be done by a separate servo/winch in a large boat, or the “out-travel” distance can be preset on small boats and only the mainsheet controlled by radio.
One more time.
Barry’s design has only TWO corners of that triangle that will move ( the tack end of the boom, and the bottom of the vang rod.) Without the third movable corner the system won’t work correctly. Yes, it is probably rigid and won’t allow upward movement of the boom, nor is it adjustable. The only way I could get that to work would be to back out the screw on the aft end of the vang rod. Then things will be sloppy, or only work in tension.