Exlex of 2018 and 2020 had daggerboads. They are simple to make but more complicated to control remotly with lines. On Amphibie Bris 15 feet long of 1989 I used a bow centerboard. I sailed her from France to Newfoundland. It worked well.
Now I try again. I like to have one line pulling the board up and one line pulling her down. The problem is to avoid that the lines interfer with each other or get jammed. The bigger angle the centerbord is tuned the bigger the problem. To get much useful lateral area I like to turn the centerboard down about 80°. Large lateral area is very useful when slowly forereaching into a gale. I prefer that method to heaving to. You can make some slow progress to windward in comfort.
The centerboard case is open at the deck. That way it is possible arrange with a lever to move the centerboard in the unlikely event of the lines breaking. I will use oversize lines. 16 or 18 mm or something like that. Big diameter lines are also less likely to get jammed between the centerboard and the centerboard case.
By being able to turn the centerboard with levers I can attach new controlling lines. Exactly how it is going to be done I have to work out but I have some Ideas. It will be more easy to see as work progres.
Here is a video. I will try to explain some of it feuters.
When a boat heels the sail area moves to lee, with that the center of effort and the boat gets more weather healm. With biplane rig if you drop the windward sail the center of effort moves to lee. The boat gets more weather helm. With a third mast, a mizzen to balance the center of effort stayes the same. Much as with a ketch if you drop the mainsail the jib and mizzen keeps the center of effort unchanged.
1964 I was a member of the Amateur Yacht Research Society. I did build a proa. To balance the sail area to lateral area I moved the sail sidewise to lee or windward untill equlibrium was reached.
Going to windward with a biplane rig is fine because both mast get free airflow like a biplane airplane.
Sailing down wind the rig is very stable and selfstearing with the sails sheated out more than 90°. With freestanding masts there is no chafe if you keep the lugsail on the lee side of the mast.
I am now trying to figure out the best stovage. There is plenty of space in the boat. This means that I have to be extra careful not to fill it up othervise the boat will be to heavy.
I have come up with a system cheap light and functional for locking the hatches. The first idea was with a rope in tension but it was not enough friction in the system despite the capstan equation. I took a walk and used the rope in compression instead. That works fine. I use rope hinges.
I am mocking up the doors between the inner and outer compartments. The idea of the inner compartments is that they shall stay dray at al times whatever the outside conditions. The outside compartments is for manouvering, tending sails, anchoring, oarwork and such. Those activities will be done from the hatch like the man in the kayak. The inner compartments are for sleeping reading writing navigating deigning and such also the saloon for eating and leasure with a 360° from the deckshouse.
Peter have helped me filming a video showing the rudder and bow centerboard.
The idea was to have a centerboard in the rudder as well and the control lines coming up thrugh the rudder axis. To make it simpler I have increased the depth of the near vertical ballasted chinerunners to 20 cm under the hull. The hull will draw 23 cm at one ton. So total draft will be 43 cm just guessing. That leaves the rudder 3 cm abouve the ground.
Its a spade rudder with a 60+ mm diameter stainless pipe as axis. That axis and its bearings should be more strong than a normal skeg.
The bow centerboard also comes along well. I have found an arrangement for the control lines.
I would have liked to have a deeper rudder. But its a balance between dept and simplicity. Hopefully it will work. If not I change it.
Below two pictures.
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Today I remowed the last mold and weighed Exlex the Canoe Yawl. As the hull now stand with three bulkheads she is 11o kilos. The hull surface is about 17 square meters. Headroom is about 98 cm in the middle of the boat. She have negative sheer by 10 cm.
First. I hypothesize that chinerunners work as deflectors, not as hydrofoils. Deflectors are concave surfaces that redirect what hits them. According to Newtons third law the more water the chine runner deflects to lee the more the boat gets pushed to windward. When the boat is heeled, the hullside together with the chinerunners creates a lot of lateral area. Unlike the ordinary keel I think the Bernoulli effect plays no significeint role here. This may explain the chinerunners remarkable efficiency and why they are so misunderstood.
Second like bilgekeels they protect the boats bottom at low tide.
Third they let me put the lead ballast a bit lower.
Forth they keep the lateral resistance high up those decreasing the heeling moment. Everyone realizes that a sail center high up heels the boat more than a low one. Not every one realizes that a lateral area high up heels a boat more than a lateral area deeper down.
Fifth the chinerunners reduces rolling.
Sixt It is likely that they prevent that turbulence a nd vortices are created along the chines thus reducing resistance.
Seventh. As the boat heels so much that the windward chinerunner lifts out of water the volyme of the windward chinerummers now mowes to lee and becomes boyancy in the lee side thuse creating extra rightning moment kind of like a submerged trimaran that lifts its windward float. The effect is not big but it helps.
Its the combined advantages of the many small advantages that makes me chose them. If at all time you can increase your efficiency even by a small bit, in the end you be doing good.
I did the line with the help of a laser beam. I heeled the boat 22.5°. That is easy on a small boat especially if you have 6 chain hoists above.
Finding sheer with the help of an inclined plane is nothing new. I guess its been don for thousands of years with the help of a string and a stick on the stem and stern. Just angle the sticks to the desired degree. This has the advantage that on a bigger boat you do not have to heel her.
At the same time I did a sheered waterline.
The hull is now on even keel. I know that the result of the operation might as planned because the hull was only fastened to the molds at the bottom. I did the lifting by the molds as can be seen in the first picture if you click to enlarge. I did shape the hull by eye to get a good shape did not follow the molds to closely.
In some places there is distances of several centimeters between hull and mold. The hull have to my eye nice harmonic shape. I liked to have a look inside before commiting myself. But it is not strong very wiggly. It will be strong later.
To get more controol and increase my chanches of a positive outcome I bought 2 more chainhoists. I now have six in total. 3 on each side. When I turn the boat left becomes right and I have to change attachment points. Now with 3 on each side I can take the load on the middle or the outer when I shift. The boat is now 2 meter longer and many times she will have to be turned around. It have never been soo easy as today. I good investment I think.