Thank you all for all the comments and replies. I have been a bit busy, but I will find time to reply you during the coming days.
In the meantime, I drew a few sketches of my intended sailplan which some of you asked. It turns out I am not very good at drawing- in my mind that picture is a lot clearer then I can get it on the paper. But I hope you will be able to understand at least something what I meant. Also, I have to add that, unlike many other things which I shared, the mainsail design is a very recent invention of mine, and I haven’t thought it through much yet. So I wouldn’t be surprised if you will spot some serious problems with it. The same goes with the “cross breed” of the bowsprit and foremast. The foresail and mizzensail themselves I have tested in real life, and I am very satisfied with how they perform. Their main purpose is steering (as I don’t intend to use any rudders).
My main consideration regarding sails and rig:
1) the whole rig has to be very strong, and able to withstand repeated capsizing and pitchpoling (think: it must be short), with minimum amount of potential points of failure (think: unstayed masts and junk-rig-style absence of highly loaded, leveraged parts), and easily repairable in a remote location (think: low-tech).
2) The rig has to be able to sustainably hold stable course on any point of sail without rudder, windvane or autopilot. That means the centre of effort must be in line with the centre of resistance (under any angle of heel), and it has to be a considerable distance downwind of it, for it to be directionally stable.
3) The total sail area is 26.36 m². For almost 13 tons of boat (2.06 m² per ton) this sounds ridiculously small, but I am not comparing this non-standard vessel to conventional cruising boats, I am comparing it to Yrvind’s Exlex, which is a little bit more similar to what I intend to do (even though it’s very light). He had 4 m² per ton and was perfectly happy with it. As “to increase speed by 60% propulsion power needs to be increased by 867%” (
YRVIND TEN – THE SAILS https://www.yrvind.com/yrvind-ten-the-sails/), I hope to be getting around 85% of his average speed in Exlex, which, if true, would be completely satisfying for us.
Here is the drawing of the sailplan as seen from the windward beam:
The two smaller sails are typical junk rig sails, with the exception that they are hinged at the tack and they have three sheets each for full trim control in both directions and on any working angle. Two of the sheets are attached to special protrusions on the boom near the tack for the sheeting angles to work as intended.
The mainsail is something very unusual which I recently came up with. It is like a cross between a squaresail and a Chinese junk sail, but with a big difference of the battens being kept at a considerable distance away from mast by “legs” (slightly similar to a gaff with its throat). Therefore for raising such battens (together with the sail) they have to be raised by three halyards- 2 of them hang from a T-shaped yard and the third is a throat halyard (similar to a gaff rig). The whole constellation of sail, “legged” battens and T-shaped yard is turned together as one piece around the mast by Chinese-junk-rig-type sheets in the same pattern as braces turn a squaresail.
My rationale behind such a strange mainsail:
1) While shunting, such a sail automatically moves it’s centre of effort a considerable distance forward (from stern towards bow), which solves a huge problem of proas regarding the shunting, which usually requires changing/reefing the sails or lifting and lowering rudders/daggerboards to make things controllable and balanced even when you use a rudder for steering (remember that I want my sail plan to be balanced and self-steer without the use of a rudder). By finding the right length of the batten “legs”, I hope to be able to balance the sail plan perfectly, so that I don’t have to even reef the mizzensail when shunting. Also, such a mainsail should be easily usable for abruptly stopping the boat during shunting, which is a very desirable feature when beating upwind through a very narrow channel, where you don’t want to lose an extra 20 metres going sideways until the boat stops during shunting. And simultaneously with this, I also completely solve the second biggest problem of all proas- the switching between its two rudders while shunting. I simply won’t have any. And Iberian orcas also will not be able to kick my rudder if I don’t even have one, haha.
2) In a single sail I achieve the best of three worlds: the junk-sail’s ease of reefing and trimming (which is especially pronounced during heavy weather), the squaresail’s superior downwind performance,
and the Bermuda rig’s aerofoil shape for efficient upwind work (I am thinking of 8% chamber in the battens).
3) The low aspect ratio of the sail allows me to keep the mast as short as possible (see my point number 1 at the beginning of this post).
Here is a quick sketch of triming of this rig in different points of sail:
I probably also need to little bit explain my obsession with self-steering and steering-with-sails. It’s not that I hate rudders (although I do a little bit), but I have never understood why people design boats with directionally unstable sailplans and then spend the rest of their lives trying to solve the problem which they themselves created- to handsteer or to use windvanes and autopilots- just to stay on that same course which they already chose once (when trimming the sails)... Call me crazy, but I see it as something similarly ridiculous as designing a wine glass without its flat base and then spending the rest of your life trying to hold it upright on a table, because it wants to tip over. And then someone “more clever” comes up with a “genius” idea- he says: “I designed an autopilot which keeps my glass upright on the table without me holding it! Yes, it wanders for about 15° in each direction, and yes, sometimes it still tips over and spills my drink, and yes, it doesn’t work when the wind is too slow, but most of the time it keeps my glass upright without me holding it all the time- what an amazing achievement…” Come on- just design a glass with a flat base, put it on the table and it stays there- that’s how it should be (in my world at least). Why should we create the problem in the first place and then spend our lives constantly solving it??? It is so easy to design sails which stay on your chosen course no matter what point of sail and what angle of heel you have at the moment. You just need a big mainsail which is the main driving power and two smaller sails protruding a considerable distance fore and aft from the boat’s centre of resistance, which you use mostly for steering. And you have to have a sheeting system which allows you a fingertip-control of the trim angle in both directions. That’s it! And you can easily steer with such sails even when you don’t have a rudder. And when you set the course, the boat stays on it, no matter what. And you can use such sails for steering/turning your boat, even if she’s not moving through the water at that moment and therefore the rudder wouldn’t bite. This ability gives you such a confidence and peace of mind when manoeuvering in an overcrowded harbour in fickle winds without engine. I agree that with using a rudder you can squeeze out a bit more extra speed for racing, but I personally don’t care about that, I just want to put my boat on the intended course and to have it keeping the same course for days without me touching anything, even when the wind is so weak that it doesn’t blow out a flame of a candle- the boat stays on course and keeps sailing. Yes, very slowly, but it keeps sailing on the right course, unless the wind direction changes. And it works in such a low boatspeeds were no rudder would be working, let alone the windvane.
And by the way, before anyone jumps on me, saying that I’m just daydreaming, and the steering with sails only is not realistically possible, I probably should add here that I have already done it a lot. Many years ago I was experimenting with steering by sails, and then I happened to lose my rudder in one bad storm. But I just kept on sailing without the rudder. My stern looked a bit weird with the rudder hinges in place, but no rudder in them. People in my local fishing harbour were shaking their heads when looking at me, but I just kept enjoying my sailing for almost half a year like that. And that happened in Irish Sea with all it’s funny weather and strong tidal currents, and it included manoeuvering without engine in tight spaces like cramped fishing harbours, tidal runs full of dangerous rocks etc. And I never felt any need for a rudder. After almost half a year of such sailing I finally made a new rudder, because I thought it’s a good thing to have in case of an emergency. But I still kept my tiller lashed amidships, and I never remember using it for the next couple years of sailing until I sold the boat. It is so satisfying to see your boat listening to you and keeping the course herself like a train on its tracks during all the gusts and waves and everything, while you enjoy your life on board.
Please let me know if you have any useful thoughts and comments about all this. I am reading your every comment, and I am honestly open to hear any unpleasant truths which you might see while I don’t. That’s the only reason for me starting this thread. I could build what I intend, without telling anyone about it, but I know that there might be things which someone else might point out to me, which would convince me to change my design before I start welding any heavy steel plates together. The only thing- please explain WHY do you think something wouldn’t work as I expect. If you don’t give any rational reasoning, but simply shout that it’s a stupid idea, then I treat you as a background noise, which I have to filter out while listening for any useful input from people who know more than I do. Or just simply happened to notice something which I didn’t.
Thank you again, and all the best of luck for everybody of you!
Artis,
www.artis.guru
