Hi David, i am up in the Vancouver area of BC, Canada. I am borrowing your idea for the windvane self steering for my Macgregor 25 sailboat, which I am planning on re-rigging as an Origami Junk Rig, as per Paul McKay. I am making a small version as a dinghy sailer currently, I will be posting stuff on it on another post. I was so excited when I saw your blog and videos about it that I designed some changes that occurred to me to cut down on some of the stringy bits that go across the stern of the boat. It's just me, I just have to mess with any design I see, to tweak it for my own amuzement and entertainment. Hopefully, if it works out as planned, it will relieve me from the tyrrany of the tiller.
I have already installed a system years ago that will hold the boat on course for a few minutes at a time, and allows me to steer the boat from anywhere from bow to stern (useful in sail raising and anchoring! I singlehand almost always). On the bow pulpit, I have attached a 60cm bungie on each side, with a 1/8" low stretch line going through small sheaves tied to the life line stantions, back to the cockpit, and with a loop tied to the cockpit ends of the lines after they go through one more turning block and loop around the tiller tied as to put a bit of tension on the front bungies. I have another long piece of bulk bungie chord that is tied across the cockpit, and that with a quick twist, goes over the tiller and holds the two loops of line from sliding off the tiller, and offering some resistance to the tiller turning. I can steer it from anywhere on the boat, including down below, with the pop top up, as I often sail in protected waters. With a quick reach to one line or another, I can correct the course. The bungie across helps trim the rudder for weather helm, of which the current rig has more than I like when things pipe up! I am so done with reefing a pointy top rig that I am bent on junk rigging her. I only want to do one drastic change at a time, so I am experimenting with the Origami Split Junk Rig on the two folding inflatable dinghies I am currently building. Wheew! What a mouthful! I spend way too much time on this, but in the days of Omicron, what is a sailor to do?
I will post more when I get further into the wind vane project. I seem to run numerous projects simultaneously, not good for project completion, but what fun! I find if I take positive action immediately when I see an idea I like, which you can imagine leads me down some interesting paths.... Anyway, here are a few sketches I have done so far.
I thought that if I attach the control lines for the steering sail to a cross T that is firmly bolted to the rotating 2" (50mm) PVC pipe suspended from the 1-5/8" x 1/16" aluminum mast tube, and carry that down to just above the top of the cockpit. This de-couples the sail from the aluminum tube, as the control lines for the sail are fixed to a 2' cross piece, which in turn is attached to the 2" PVC pipe. I can have an adjustment mechanism whereby there are two discs of material, HDPE or some such; the bottom one has a hole through it to fit the pipe, followed by a cap drilled out to 1-3/4" for clearance, to center the 2" pipe. The aluminum tube runs up to the top inside the PVC pipe and down to the bottom of the second piece of PVC 2" pipe, about 8', as the aluminum tubes I can cheeply procure are about $33 CDN each are of that length. On top of the lower disc, there will be another one with a strut sticking out 16-20" (experimentation to be done to determine how long the lever arm needs to be). The lever arm will be attached to two lines that run from the lever arm to turning blocks, one on each side with geometry to maximise the leverage from 0* to 45*. This way the lever arm is designed to stay in alignment with the rudder and the sail can be aimed in alignment with the wind direction, coupled by the two discs at cockpit level via locator pin. From the lever arm to a crossbar with a block at each extremity, that is attached to the aluminum inner mast. From there, back across the cockpit and then to the tiller through another turning block mounted on the lower pushpit. This utilizes the 2" PVC pipe as a transmitter of torque from the sail turning to the lower lever arm. There will be an index hole in the top disc and a series of holes all around the lower disc in alignment with the hole in the upper disc to get the sail/rudder alignment right.
The bottom pipe will be fastened to the stern, cap on the botom, drilled cap on top with the 1-5/8" aluminum tube running from there up to the mast head where the haliard and the lazy jacks will be attached. The aluminum inner mast will have a way of indexing it so it always stays in the same orientation, a pin that is clamped to the aluminum mast with an indexing pin, like on David's rig. I am planning on attaching the 2 blocks that go to the lower lever arm to the aluminum inner mast, thus keeping the whole rig easily removable for trailing. (it is a trailer sailer). Wheew! Marathon derscription. hopefully the drawings, more like doodlings, will elucidate my points. Now, ...to work! I will. post pics as I progress. Next job is getting some welding done on the trailer. Rust never sleeps! The drawings are dated and sequencial, showing the thinking that went into the changes I planned.
I have the mast and the pvc pipe, loads of polytarp and low stretch poly line, 1/4" grommet system from Sailrite, and other buildy bits like aluminum bar stock and HDPE cutting board. I have drilled the caps, but that is it so far, not much to show. As they say, the devil is in the details. Friction is my constant companion, may it's highs and lows be of use to me in the functions of the system.
Anyway, I despise politics; I have been riveted by the Canadian Truck Ralley in Ottawa, waiting for our 'leader' to show tomorrow on Ground Hog Day, and see if he will see the shaddow of a convoy parked outside parliment and scurry back into his hole for another 6 weeks! You lot over in Britain have just chucked all the controls away already, let us hope Canada does too so we can try these scoundrels for treason! It will be a day to remember in Canada when our Covid 1984 wall goes down! Unlike our government, I HAVE been following the science... Maybe we can get back to actually treating illness now.