Monoproa v. 2.0 - New sailing video
I have been trying to twist my mind around this beast for some time now, and it is finally time to build another scalemodel to test some ideas..
The biggest problem with my previous monoproa was that it would kind of pop into and out of multihull-mode while sailing through waves. It had to much righting moment and had an extra drag-inducing chine under water.
This time i will make it even more simple then my previous monoproa, and i will sacrifice some righting moment and carrying capacity to have a much more sharp chinerunner-enhanced lee chine and, what i hope will be, a low drag hull shape. I want to avoid the brute-force approach from last time, and try to get some “proa” back into the monoproa.
Cheers,
Johannes
Johannes
can you link us back to the Monoproa 1 thread?
thx
Simon
Monoproa - beam seas - Youtube
I will post more tomorrow.
I have been sailing our monohull all day today.
Cheers,
Johannes
Yesterday we were sailing, so there was no progress.
Today i have started lashing together the bottom part and the lee side with cable ties.
I have a rough sketch of the cross section at the widest part of the monoproa.
I have tilted the bottom of a sharpie hull, to get a sharp pointy lee chine. It will become a slightly asymmetric deep V shape when heeled 10 - 20 degrees.
And a picture of the chinerunner protruding out from the 72 degree sharp pointy lee-chine. I think this will work wonders for upwind ability.
Cheers,
Johannes
Two more pictures. I have not attached the windward side yet.
I hope these pictures explains the shape a little better.
It is 121 cm long, 22 cm wide, 7 cm deep at the lee chine. 12 cm high freeboard and 10 cm high ends.
It will have a small leepod. A real full sized monoproa would have some kind of water-ballast near the windward chine. The water ballast should only be used in heavy weather, like on Jzerro. To much weight to windward is detrimental to sailing properties. It made my last monoproa behave bad, with a jerky and twitchy movement through waves.
The waterline width will decrease from 22 cm to about 15,3 cm at 25 degrees heeling. From 5,5:1 L/B to 7,91:1 L/B @ 25 degrees heeling. I hope this will help the monoproa get some impressive speed potential. I know my last monoproa was fast, once heeled over 20 degrees or so.
Cheers,
Johannes
Monoproa sailing on the bad tack - Youtube
I found this old video of my old monoproa sailing on the bad tack.
I think it is interesting to see the striking difference between the two tacks. When the bulging rounded multichine windward side is pressed down into the water, the monoproa sails like a brick. On the right tack it is much faster and tracks straight through quite confused waves breaking near the shore.
Cheers,
Johannes
I use some scrap pieces of rebar as ballast. It adds 1,1 kg of mass concentrated low in the center of the hull.
Now i am waiting for the epoxy fillets to cure…
Johannes
I tried to draw the waterline @ 25 degree heeling.
I think the underwater hull-shape looks good. Very clean lines.
Johannes
I could not wait any longer. The epoxy is hard, so i took away the masking tape and the cable ties and threw it into the water.
I tested the RM by leening it over both ways, and the RM was the way i expected it to. There is less RM when leening it over the “right” right way (to lee) then to windward. I believe it can be a little tricky to sail it at a fixed heeling angle of 20 - 25 degrees, since there seems to be no large increse in RM from the angle when the windward chine gets above the surface. Once heeled it was really easy to pull through the water. With the right rig and sails i believe it can be fast.
There was a lot of lateral resistance when i tried to pull it sideways. It acted as a plow and just dug into the water. It was soo effective it left a big cavity behind the hull from where the chinerunner is.
Cheers,
Johannes
A short video of the new Monoproa. I test lateral resistance and RM.
Johannes
I tested the righting moment in a almost scientific way.
My clamps weight 150 grams each, and they are 50 cm out from the rotational center of the hull.
There is not much difference between the two sides. The difference is larger at greater angles, but i did not take any pictures of that.
Johannes
The only boat i can compare my monoproa to is my Paradox.
The scalemodel is 83 cm long, 20 cm wide, 5,2 cm deep, 12 cm freeboard, 4,2 kg.
My monoproa has more RM, but that is expected, since it is 33% heavier and 2 cm wider.
Johannes
I have painted the monoproa in a heinous brown color, and i have made a new crab claw sail today.
I want to test a new slightly smaller Wharram soft wing sail, but the CC is both easy to make and plenty powerful. I have been longing to sail a CC since the last blew out to sea and sank.
I hope i can sail it tomorrow, when the paint is dry.
Cheers,
Johannes
I have been thinking about casette-rudders for these scale model, but i don’t like fiddeling with stuff in this small scale, so i welded together a piece of 1,5 mm steel sheet with a threaded rod. There is some grinding left to do before its smooth enough.
I don’t think i have to worry about denting the rudder when sailing over a rock-strewn bottom.
I will glue a small block of wood onto the inside of the bottom on each end, and then drill a 8 mm hole through the block and the bottom plywood. I will only use one rudder, and manually change side every time i want to change sailing direction. I usually only do that once every time i test sail my scale models.
Johannes
I tested the monoproa with the new crab claw sail, and it was a failure.
The monoproa behaved like expected, but the crab claw is not suitable for a monoproa at all.
Way to variable lift angle and CE dependent on the angle the monoproa was leaning.
I will make a new sail and rig soon. I hope i can test it next week.
As usual i get more new ideas i want to test. I should not test these things, as it only spurs me to keep on experimenting.
Johannes