artis
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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
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
