Sailing Trial of the Model on London's Round Pond

I put an extra slab of material into the foot of the main and a triangle into the foot of head sail and took her down to Kensington Garden's Round Pond.
There was the mildest of breezes as you will see from the surface of the water.
I had no radio control and found a position on the pond that would allow a reach. I used a trout line to retrieve her.

Some Discussion and Pictures of the Prototype Model

In making this model I have duplicated the hull I used as a model for Tuanella 3. As mentioned below things are not right. Nevertheless I shall continue with this hull for the time being just to work out things like sails which you will see are painfully small and the head sail in particular is badly cut.

[At the outset I sensed that the proportions of this hull were not quite as aesthetic and functional as I would have hoped. The hull length to beam ratio for its moulded depth(keel to deck measurement) needs refinement. Allowing that I shall aim to pursue the construction  of each hull from what is effectively a single sheet this will amount to no more than altering the length to breadth ration of that single sheet. 
I shall use Xray film in the first instance. This very accurately simulates sheet metal in its resistance to deformation and its 'wangi-ness'. Thence make it in thin aluminium with three ply decking.]

Both hulls of this model are of steel and it is quite a hefty item to lug around. In aluminium it will be half the weight. Despite the weight and rough sails she moved quite nicely on the Round Pond at Kensington Gardens in Hyde Park.
Some pictures show her being built.
   

     

 

The Need For A Genuine Peoples' Catamaran - A Folk Cat.

In a world with an expanding population, where the present margins of its land mass face reduction as the ice caps melt, and one where many thousands of us will thus become homeless there is a need for finding an easy way of living on the sea or on the sea edge.

Global weather irregularities in the last few years seem common and might indeed be a reflection of global warming. Many scientists think so and are giving us the parameters in which we must live to avoid calamitous overheating in the future. Sceptics might propose that our 'now' is a blip; they could be right; however in the meteorological history of the world blips can mean many tens if not   hundreds or thousands of years. I think it is best to be cautious and to take the default situation of 'warming' as real till proved otherwise. 

The shortage of land for those where housing was on low lying waterside have a way out. Of course nothing is quite like the feel of terra firma but in many countries whole rafts of people live on junks and boats at the water's edge and have developed occupational and social life styles that go with it.

No doubt for many such  people there was no choice, the craft under their feet is cheaper than the cheapest apartment. It doesn't have to be a hovel. In effect such 'rafts' of these occupied craft may indeed be preferred to shanty towns, not always the healthiest of places to live. 

In a more salubrious setting tens of thousands of beautiful craft lie, with electricity, water and sanitation at hand throughout the wealthy world in what might also be seen as rafts - marinas. That they are mostly unused, idle and empty is not under discussion. But they, for the most part, except for serious storms, offer good accommodation with little disturbance year long - some rocking, some heeling, but easy access to shore, car parking and often public transport.

Most by far are monohulls.
Catamarans on the other hand offer a more stable and capacious craft with the dual hulls allowing of a convenient segregation for family life and the interconnecting platform perfect for communal socialising and galley facilities.
Patently vulnerable to extremes as we have seen in tsunamis but so too were much of the other housing on the waters' edge.

Without doubt catamarans are more expensive than mono-hulls if for no other reasons than that they have two hulls.
This imperative cost might in some way be radically mitigated
 - the hulls are identical but do not need the degree of hull strengthening of a mono-hull to accommodate hefty keel forms.
- the inherent stability of catamarans, not relying on the 'ballast' effect  means the whole hull can be very light throughout.
- cheaper construction methods thus can be used not suitable for mono-hulls.
- new configurations of the hulls to each other can radically increase the below deck capacity of the mono-hull form yet move the buoyancy laterally and enhance stability.
- new platform arrangements offer the potential for many centre keel configurations that global sailors might wish to install.

I am proposing to build a catamaran that will be more that usually capacious below deck, cheap to build, perform well, and of an easy rig, it will be easy to sail. It will look different but be attractive.

In the future, allowing my boat is successful, I see the general construction to be completed by a specialist company or yard and the finishing left to the buyer or outfitters of their choice - in the manner of Rolls Royce cars in days gone by where RR produced the engine and chassis and the likes of Mulliner - Park Ward and Hooper in the body work and finishing off.

I shall keep you up to speed on my thinking and the practical development as it occurs.

Thinking About The Hull In Catamaran Terms.

I mentioned earlier that T3 was a too floaty boaty so naturally the vision of it being useful as a hull for a catamaran crosses one's mind. It seems in the advertisements for catamarans that lightness is a wanted feature and understandably that would make sense when it comes to speed, handling and costs. What I would be interested to know is how lightness of a craft and specifically that of catamarans works in heavy weather sailing. If the craft is too light and sits high in the water and is very beamy, is she more subject to uncontrollable behaviour in a hoolie and more likely to tip than a heavier and more narrow boat? Old fashioned mono-hulls let to ride out a sea, a- hull, with warps, drogues, sea anchors etc -(http://bit.ly/1mr53Um),being heavy might, or could, be seen to settle better and be stronger than a lighter craft in such turmoil (breaking waves)
The original drift of much of my design was to produce a craft that would be efficient in moving through the water i.e. have no wake but also to be safe at sea and I think that having most of the buoyancy well forward would mean less likelihood of pitch poling, a danger for which one of the best options offered was a series drogue.
   By exactly the same token now confronted with a drogue the fine section aft of my hull(s) allows such sea surging from behind to 'part' and not push the hull forward at the same speed i.e. facilitate the purpose of the drogue. The hull pushed at or near the propagation speed of the wave form will be confronted with that which is seen to happen to the superficial part of the wave ie the change in direction as it crashes down. If the nose of the craft is prevented from sinking by forward buoyancy and if the sharp aft  parting the crest or top of the wave slows it down then the transit of the hull is more likely to be  horizontal or at most a flatish wave form.
However the issue of lightness persists as a worry for what I hope will be a 'folk' cat for ocean sailing. It is easy to see a very light cat being flipped by an irregular sea, let alone breaking waves, so one is immediately confronted with the prospect of having to make the craft heavier.
 A Keel For Safe Sailing In a Catamaran

Such keels as catamarans have tend to lie along each hull. A keel suspended from the platform or connections between the hulls might have some benefit. The keel may be pinned forward on its upper attachment ( in the plane of the lubber line) and so pivoted it can between all up or all down. It  can be boxed and lifted wholly up or down by perhaps some rack and pinion arrangement.forward to allow it to go up and down. Also the keel can be bi - pendulate, and fitted with some manner of a bulb that can be rapidly filled with sea water  and offer steadiness that way.

By the hinging of the keel in the lubber line at its upper attachment allows an adjustable bias in that it can be swung to windward easily - of course this stiffening of a catamaran might be folly under sail unlike a monohull but it is for toxic sea conditions that such a keel might reduce the likely-hood of tipping.
For light airs it can be lifted. For severe weather and concerns about the stability of the craft in large wave conditions the keel may be fitted with plates on each side hinged at or near its bottom edge such that they are free to fall away  a limited amount , to  ‘open up’ like an umbrella when sudden upsurges in the hulls occur. Such opening up would create a vertical drogue and resist wave and wind to topple the  boat. Downward motion of the hulls would tend to ‘close’ them and allow the hull to settle into the wave form  till the next upsurge opened them again. 

 I cannot quite decipher at what component of the wave form the boat is most vulnerable to tipping but it is most likely to be a mix of sliding on, up or down, the wave form and either stalling in speed, and so being overtaken, or falling off a crest or tripping into a trough. The wind situation makes things more complex.  

                            

As mentioned the bottom of keel might have a bulb that is hollow and that can be filled with water as necessary. In the water itself the only contribution weight wise will be that of this container. However the form, should it be fusiform or tear drop shape could have the plates mentioned above hinged along it lateral margin. Being round in section such plates would offer up a cusp concave uppermost and be ideal for acting as a vertical drogue.