Unusual design for an extra-heavy-displacement 11ft long Atlantic Proa for circumnavigation

I am currently designing an extremely unconventional sailboat, which we as a couple hope to sail around the world, and if we are successful, that would also set a new Guinness World Record for circumnavigation in the smallest boat.

I have been thinking through a lot of things on my own, and I would like to ask you, all the knowledgeable and experienced people on here, if you might be interested to discuss this design and point out any possible problems and difficulties in it.

As you can see from the attached drawing, the design is technically an Atlantic Proa (the one which always keeps the outrigger to leeward), but unlike conventional multihulls, it has an extremely deep draft and heavy ballast.

Below are my main design considerations.

The main focus of the design is to build a seaworthy boat which would move in a pattern that would cause the minimum amount of sea-sickness possible. Due to my woman being quite prone to seasickness, I see seasickness as the highest of all the risks why our circumnavigation plans might fail. And because of that, we are happy to sacrifice many other things, such as speed, draft, conventionally acceptable looks etc.

Here is my train of thought:
1) The boat’s design has to minimise any rolling movements, as they are the component which makes the brain seasick. Straight up-and-down movements doesn’t matter, because our brain is perfectly accustomed to them, since it is the same kind of movement which our vestibular system gets when we walk.
2) In order to cut out the rolling movements, the hull must be mostly submerged, float vertically and have vertical walls, which eliminates any shape-stability and leaves the vessel with mostly vertical movement in waves (like a pencil with a lead attached to its end, floating vertically, 3/4 submerged). That means extremely deep draft compared to its length and beam. The inspiration came from R/P FLIP (RP FLIP - Wikipedia https://en.m.wikipedia.org/wiki/RP_FLIP).
3) In order to have a vertical hull which is still manageable under sail and sculling oar (without engine), it has to be extremely short and narrow, in my case: the length of 3.5m (11.5 feet) and the main hull beam of 1.1m (3.6 feet), with a draft of 4.5 m (14.8 feet). This kind of crazy contraption would have a fully loaded displacement of 12,780kg (28,175 pounds).
4) In order for such a hull to be capable of carrying at least a modest amount of sail, I add to the hull an outrigger. But as I want the minimum possible roll movement induced by the breaking waves of the Southern Ocean, I put the outrigger only on the leeward side of the main hull (hence the Atlantic Proa). That way the bashing of the steep wave faces would be taken by the main hull’s vertical convex wall, and the hull would respond to it mostly by lifting up vertically through the wave, instead of rolling over to the side. The back of the wave is not as steep, therefore the leeward-outrigger-induced roll should be relatively small. But for it to be still tolerable, the ama should not stick out to leeward too far- just enough to enable the unstable hull to carry a modest sail area, enough for a slow cruising.
5) As one of my big concerns is if such a hull would sail enginelessly at least as close to the wind as the old square riggers did, I minimise the windage by having a small above-water volume (compared to the excessive underwater volume), which makes this boat to behave almost like a surfaced submarine. I also streamline the pointed hulls and outrigger, and I take advantage of the proa design and make the leeward sides of the hulls absolutely flat and vertical, which will maximise the lateral resistance, as well as giving a hydrodynamic lift towards the windward side.
6) I plan for an enormous amount of storage space and load caring capacity in the deep bilge, enough for carrying 1 year’s worth of our provisions. With this heavy design I can afford it, and also it would give us a lot of wiggle room in terms of where and when we re-provision. That is especially important since I don’t expect such a boat’s speed to average more than about 2 knots.
7) The deep draft’s imposed limitation regarding shallow anchorages should be more than outweighed by the ability to anchor further out and in rolly anchorages, or simply staying heave-to in the open sea, while still having a pleasant living conditions aboard due to the lack of roll.
8) In order to maximise the living space on the very short boat, I make use of it’s deep draft and create many floors. As an added bonus, we also get an extra room with underwater windows (like in the concretesubmarine.com), which always stays pleasantly cool, even while becalmed in the middle of Indian Ocean.

What do you think about such a design? Does anyone of you have some experience with anything remotely similar to this? Or does anyone have enough theoretical knowledge and strong imagination to be able to predict how will such a boat behave herself?

Thank you in advance for all your thoughts and input, have a great day!

Artis,
www.artis.guru

 

Hi Artis

Why do you think the boat will not develop more than minimal roll motions, depending on sea states and wind?

That's not right. Our brain absolutely doesn't like vertical acceleration the amount you would experience at sea.

 

Build it as designed and see what it's like in a seaway.
If you like the ride, go for it!

I couldn't get through your text.
The drawing lacks propulsion...
Is it a drift boat?

EDIT: Ah, sail. Where's the mast.
Can you draw an isometric of it complete?

 

Hi Heimfried, thank you for your comments!

Why I think that this hull shape will have much less rolling motion is the experience of the R/P Flip. When it was flipped vertically, it didn’t move at all, even during heavy storms (there are some videos about it in YouTube, you can search: flip ship). It didn’t even have any up-and-down movement, because it was so long and heavy while having proportionally tiny waterline area. That’s the basic principle how also any small-waterplane-area twin hull works (Small-waterplane-area twin hull - Wikipedia https://en.wikipedia.org/wiki/Small-waterplane-area_twin_hull ) My design of course, is nowhere near of the same proportions and size which the Flip had, but nevertheless I expect the same principle to partially work for me as well. I hope to achieve the movement which is somewhere in the middle between a conventional yacht and the Flip. I expect it to act almost the same way like a fishing float does in waves. If the float is long and weighted at the lower end, floats vertically, 80% submerged, it does not roll in waves at all, it simply moves up and down with the waves.

About the vertical acceleration forces that upset the brain. Are you really sure that 13 tons of steel with only 3.94m² of combined waterplane area (2.76m² for the main hull and 1.18m² for the outrigger float) can have more of a vertical acceleration in waves than what we have when we are running or jumping? That would mean that the boat should be dropping down so fast that at times we would lose gravity and start flying in the saloon, and even that would be exactly the same, as when we run (when we are also flying between the steps)… And nobody has ever gotten seasick from running…

 

Yes, it’s a sailboat. I plan for three masts, a big mainsail in the centre, and smaller mizenmast and foremast which would stick out a good distance aft and fore of the boat. The two smaller sails would be mostly for steering and for the boat to keep a straight course, because I intend not to use any windvane and not even a rudder.

I have also a lot of other details in my mind which are not shown in the drawing. I will try to find some time tomorrow to draw a bit more. But I am not sure if I will be able to do an isometric drawing though.

 

congratulations on truly the absolute worst concept I have ever seen,,, just start again from scratch,,, please....
4.5m draught...where the darn are u going to launch it from,,, dont get into details,, just throw it away and start again,,, or buy a little dingy from the local town

 

Artis,

Thanks for your reply.

You need a little more thought put towards how you're going to build it.
Drawings are a great way to communicate and move forward with the process.
If you can draw it all, right down to the fasteners you'll quickly see what works and doesn't work.

Or just build it, then you'll see what works and what doesn't.

Draw all these extra ideas you have.

What's the budget and timeline?

 

Maybe opt for a kite rig vs sails. A boat 4m deep and 3.5 m long might possibly drag better than sail...

 

Thank you for the opinion Peter. Would you mind explaining where exactly lies the problem with the draft of 4.5m? From what you write, I see only the issue of finding a place where to launch her from. And if that’s the only problem, than my conclusion would be that we don’t have any problems at all here.

 

Yes, I definitely intend to draw more as I move ahead.

both the budget and timeline are stretchable for me: I will be done whenever I am satisfied with the result, and I will stop spending more money when everything is finished. Of course, I understand that buying and welding together about 9 tons of steel will cost something, but in general, I am quite good at making something out of nothing, so I intend to spend the very minimum possible.

 

Thank you for the suggestion. I had been thinking about it actually. But so far what keeps me away from the kite rigs, is the amount of high-tech required, which would be difficult, expensive or even impossible to repair on my own in a remote place somewhere in the mid Pacific. In general, I want my rig to stay up and self-steer the intended course without using a rudder or an autopilot, even in unstable 3kn winds and even while I’m asleep, and to do all that without requiring any electricity. My intended rig should be able to do it quite nicely. I hope to find a free moment later today to draw it and attach it here.

 

Essentially your proposing an elongated channel marker bouy, an object traditionally used for stationary use. Not exactly an ideal shape for movement. What makes you desire a vertically oriented vessel as opposed to a traditional shape?

 

I agree, but with one exception: it looks like a marker boy, only if you look at it from the end, not from the side. The main hull has a 3.18:1 length to beam ratio, and a sleek hydrodynamic shape with pointed ends. Wouldn’t that make all the difference? And by the way, I don’t expect her to sail any faster than 2 knots on average, as I already mentioned in my initial post.

 

The points 1 and 2 in my initial post, where I started this thread.

 

To quote the princess bride " I do not think you know what that word means" in reference to sleek.

A mast tall enough to overcome the substantial resistance below the water line is going to likely cause some fore and aft heeling. Like pushing on an axe handle near its extreme end. That's a tremendous amount of "boat " and i use the term lightly on the vertical axis, it's going to need some yardage to make it move.

The other thread were small vessels with very little comforts designed to require very little sail to push along. All the living space equates to displaced weight, that requires more sail... that in turn will make the sketch rock like a child's hobby horse.