I have been thinking about this on and off since i first saw the Rozinante II. I just have to test this idea. There seems to be something intriguing lurking in that strange crossroad between the pacific craft and the western monohull.

I bought one sheet of 1/8 inch birch-plywood today. I hope i can build a scale 10:1 model of something similar to a Paradox-like -monoproa. A shunting for and aft symetrical monohull. I hope i can get some help from some of you on this forum. There is a lot of knowledge on this forum and i learn new things every day thanks to everyone posting here.

I imagine myself a lateral assymetric Paradox with a L:B of about 5:1. The leeward side having a balanced rocker like an Advanced Sharpie and the windward side much more rocker.  I don’t know if one would need the chinerunners, but i believe they would help. Simple stem-hung cassette-rudders that is easy to lower or pull up from the cockpit.

As Michael said in the original Rozinante II article: “and the looks she would get at the dock would be absolutely priceless.” I think its almost worth building a 6 X 1,2 meters boat just to scare the crap out of sailors around the westcoast here in sweden.  Many sailors are so conservative and boring. Sweden is probably one of the most multihull-antagonistic countries in the world.

I will post a sketch of my ideas soon.

Any and all thoughts and ideas on this matter is most welcome.

Johannes

Something like this.

I have been thinking about making the windward side multichined, but the leeward side only a single 90 degrees chine - like an advanced sharpie. I think that would make the hull smoother in a rough sea. The hard chine would otherwise try to lift the windward side. It might even be a good think to make the windward chine with strip-planking to create a smooth round shape. I think the hull should be assymetrical both in rocker and amount of hull “protruding” out from the center-line, and in general shape.

Johannes.

I just have to say I think you could get a great cockpit out of those dimensions; both self bailing and enough protection from spray It’s nice only needing seating on one side.

There is one potential problem I see. It seems that if the lee side is relatively vertical, and the windward side has more bulge to it, the righting moment will not be very great until the boat is healed over quite far. I’m not sure, just guessing. This could potentially be less of a problem if the crew is actively trying to keep the boat upright with their own weight or water ballast. Or perhaps there could be some keel weight permanently canted toward windward.

There is one potential problem I see. It seems that if the lee side is relatively vertical, and the windward side has more bulge to it, the righting moment will not be very great until the boat is healed over quite far

Yes it will heal more than a multi-hull, but i don’t think its excessive. It need to heal over something like 15 - 20 degrees. I’m thinking a leepod structure that start touching the water at 25 - 30 degrees, is probably needed. Its a great place to have all the random stuff that somehow accumulates over time. One should not place heavy stuff there, but pilot-charts, gps and a thermos with coffee or té should be perfect.

Since it heels the same way all the time, and never in the opposite way, one could make the seating inclined the right way.

Thanks for your drawings and thoughts on this matter. I don’t have a clear idea what this boat should look like. Its a very new concept to me, but i find it very interesting.

Johannes.

I don’t know how to paste a link on the old iPad, but go to YouTube

search “monohull shunter” and “tsstproa” for an account.  he did models right along these lines.

Tom

Thank you Tom!

I have seen that shunting mono many times, but its just as fun and interesting every time i see it again.

Tsstproa mono-shunter

This is a great part of my interest in shunting monohulls.

I think Michael Schacht pinpointed the main advantage with the shunting monohull:
It get more slender and more symetric as it heels.
A 5:1 L:B shunting mono with the right shape on the windward side should have something around 8:1 L:B when sailing with 20 degrees heel. That is very slender and probably very fast. I think one should take care not to think to much of the asymetry. It does not solve many other problems. The shunting mono should be very similar to a tacking mono in weight distribution and total weight. I imagine it should be quite slender to begin with as the windward side tends to become to wide compared with the length.

Today i started to draw out the bottom part on a piece of plywood.
It might take a while, but i hope to test-sail it before the ice covers my nearby lake.

Johannes.

I’m building a model of Black Swan this week and this post made me consider the possibility of an asymmetrical sharpie or perhaps very shallow V hull. I wonder if the flatter lee side could “fool” the water into thinking the boat is more slender than it really is. This all goes with my crusade to get a fat proa hull to perform. So many models to make, so little time… 😉

Black Swan getting more laterally asymmetric is all part of it becoming a black swan.  Keep the sharpie, but make it a proa.

Looking forward to the next installment.

Chris

I wonder if the flatter lee side could “fool” the water into thinking the boat is more slender than it really is.

I think a slight assymetry could help. The assymetry should compensate for the higher pressure on the leeward side, created by the wind-pressure on the sail(s).
One has to take care to not create to much drag on the windward-side. I think the lee-side should have a sharp chine, but the windward side should have a more round and low drag - shape.

Johannes.

I have been making some sawdust today.

The first picture shows how i draw the radius. Thank you MTP for showing me this very simple way of doing it.
This show the general layout and shape of the mono-shunter.

Johannes.

One more picture showing the assymetry on the bottom part. The windward side will have an aditional piece of plywood at 45 degrees angle to the bottom. Its mainly to make the waterline-width shrink when the boat heels.

Johannes.

Making more progress. Im incredible tired today. I have been fighting chronic fatigue syndrome for 14 years now, and some days are wors than others. Im working 15 minutes at a time.
That last piece is awkward to shape. Im trying to fasten it temporarily to the hull han just drawing along the edges to the plywood, but its complicated to get it right….

Johannes.

Thanks for the updates Johannes, CFS notwithstanding. An extremely interesting project. I’m doing well on my model, should have something of interest to post in a few days.

I’m doing well on my model, should have something of interest to post in a few days.

I hope it will not take to much time… Your Black Swan is very interesting and i believe in the general concept.
Im very much looking forward to pictures and (hopefully) a video of any test-sail of your model.

Im trying to get that last piece to fit, and that takes some time. I will make two different models before i mix any epoxy. I need to test one more model of my advanced sharpie proa before comitting with the vaka. I want to test slighly overhanging ends. Same blunt nosed shape, but not vertical. Some much diffent ideas, so little time.

Johannes.

I’m spaming away with pictures.
With a little help from my new beltsander, i got the piece to fit.
Now i just need to mix some epoxy.

Johannes.