An Update On What I Am Doing Now.

The failure to appropriately ballast T3 left me with two options. One was to re-ballast: this would mean the opening to the engine well inside the boat would be so close to the waterline that the chance of swamping the boat from inside would be great - dangerous from heeling and rocking except perhaps on a mill pond; removing the engine well and the outboard engine arrangement and replacing it with a hefty inboard well forward where there is maximum buoyancy, and offering up a long shaft along the sole with a standard propeller housing aft would solve this. Thence I could re-ballast to my heart's content.
The other option, which I am now taking, is to deprive the boat of the hefty lead filled aluminium ballasting keel and take the view that she will sit on the water, precariously of course, on her sole.
She will sit like those pond insects - water skaters - barely infringing on the water's surface tension.
Of course she will be impossibly unstable like that and tip immediately.
That is where the outrigger I am building comes in. That, by virtue of its weight and disposition will keep her upright and hopefully, because of its minute draft, and bow form, offer little resistance.
Such a plan means I can keep the present engine well arrangement.
I am doing this before the re-ballasting mentioned above simply to investigate the potential of the option. I am not hopeful of a resplendent outcome but it is a 'suck it and see' situation.
The cumbersomeness of transporting what I'm building pressures me to build in some sort of folding
mechanism for the outrigger to lie against the hull during transit. Such an arrangement required some modelling and I show below some of it, however crude, by way of determining the hinge arrangement. This latter has to accommodate the lines of the hull, the folding of the outrigger to the hull, and fixation to the hull when it has been lowered.

Such hinging I'm sure one can appreciate has to be rather outsize. I show a mock up in mdf  and wood to get a perspective and the clearances right. I propose to make it in aluminium plate, and the welding of  aluminium tubing to it to accommodate stainless steel rod to form the hinge. I have tried to demonstrate on the model the need for the hinge mechanisms to have a universal flexibility to allow for the curving lines of the hull.

This attachment near the water line needs some flex-ability there as the pontoon outrigger has to find a 'best fit' position in relation ot the hull when it is lowered into the water. Stabilisation will come from  a fore and aft spare which will come from the gunwale  to the far side of the pontoon. These too I hope to make adjustable, again to fine tune a 'best fit' when she is in the water. I hope the triangulation provides a stiff enough purchase! 

The shown siting of the hinge below is too central but was just to show the hinge above in place.

It also shows, as does the picture below at the aft end, the added bolstering of the pontoon deck where it will receive the hinges and gunwale struts.

In both a central pillar connects the deck to the bottom and thus hopefully spreading the stresses between it and the hull.

This shows the general lie of the pontoon, fore and aft, and is pretty close to where I expect it to sit against the hull when both are in the water. It looks very long in the above but is only 8 ft and is gently tapered, the width across the nose being shorter than that across her stern. This is to keep her outer side parallel to the T3's lubber line and the inner side pretty much the same with respect to the hull side.

Some Observations On Her Run On The Pond.

The hulls are steel and heavy and the rig probably barely proportional for her size. Despite this, and in the absence of any self steering and rig adjustment for her aspect to the breeze, she got along at a fair old pace. I trust that this is a reflection of her hull shape. The almost complete absence of heel means there's virtually no spill as one would get with a mono-hull so in a real life situation the rigging must take an immense hammering when there are gusts -  of course if the hull is compliant and the set of the sails is good then the hull speed should shift considerably - such compliance safeguarding the rig to a degree.
Of course one can have hefty rig or just be vigilant in easing it in gusts and blows.
What I did notice was that when the breeze was stronger and more aft that her nose dug in somewhat. naturally more on the lee hull, and this despite having most of her buoyancy forward and with her rounded nose.
How much more would this have been the case had the bow been fine and the bulk of the buoyancy aft!
One of the prime motives for proposing the generality of the reverse hull idea is that it might be a safer one when running before the weather and sea.
On the pond one of monohulls, well laden with lead ballast, showed particularly good steerage, going almost faultlessly straight when pushed from the shore. When pushed out with the sharp end as the bow there was no directional stability at all. I can suggest reasons for this though I don't know how valid they are.
As the bow ploughs into the water, at that front, there is likely to be a quite a mixed population of eddies and waves etc present at the time and then those generated by the forward movement of the hull, both in the water, at the interface and in the air above these. One would think that a sharp bow would generate less forward disturbance if any at all. But like the keen edge of an axe descending on a block of wood slipping rapidly into what would be the mean of the grain(s) in the wood, the sharp bow with much of it above as well as under the water now finds quickly the mean of the water currents, edies, and any wind above, and the hull mass like the hefty back of the axe head allows those influences on the bow to determine her direction.
In the case of a rounded bow its bluntness is aggravating the water it is entering already, compressing and generally lining up at right angles to itself that population of variant forces and making them one
or less numerous. Cut into them it must the bow now is pushing through this somewhat prepared and now more homogeneous milieu. It parts and such banked up energy as occurs from this parting forms a pressure head, equalish on both sided of the lubber line and as the greatest width of bow curvature passes this it dissipates its energy in squeezing the hull aft of this greatest curvature (width) forward.
I might have said it before but I heard somewhere that perfect hull would leave no wake.

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.

Tuanella III - Quo Vadis?

Things look rather grim for T3. Exceptionally tender, under-ballasted, poor trim, and an engine well that might let in lots of water when these are corrected. Seemingly a dreadful waste of time, energy and money. To start with I built a model which went slipped through the water like a seal but in extrapolating up to the present project  made some real errors in calculating her ballasting. Determining stability and tenderness never crossed my mind partly because as well as the still waters of ponds around London I took the model to the rougher waters on the River Hamble where again, when pushed, or towed, she slid as effortlessly through the chop as the mirror smooth ponds, thus impressing me with her stability. Of course the model was very well ballasted indeed.

 The weight she had on board was for her 31inches (79cms) length was 13.75lb (6.25kg). The weight of the model's steel shell was 6.05 lb (2.75 kg). an all up weight of 19.8 lbs (9kg). At these weights she sat in the water just over half way to the gunwales amidships and slightly less aft.
In extrapolating those weights to T3's length, some 7 times that of the model, I think the weight hike will need to be like that of the volume hike ie the cube of that ratio or 1/7 scale.
The cube of 7 is 343 so if this idea is correct that would mean T3's all up weight should be 6791.4 lb (3087kg) or 3 tonnes.
If that calculation is to be believed and as her actual all-up weight, engine, cabin, lead filled keel pod and accoutrements was 1155lbs (525 kg), one imperial ton or half a tonne, it is small wonder that her footprint on the water was that of an 18' canoe.

Back when I was playing with the model I rang the test tank people at Southampton and they quoted some runs there and calcs against established data for some £2500 pounds.
That seemed a lot. I thought for that much I could knock up a 'life size' model I could actually test with me in it and in many way this, in material terms, was not that wide of the mark.
What was wide of the mark was the other big costs - time - I was working part-time as an obesity adviser - and rent and rates of the space I had here in London to do it - this by far the biggest killer financially.

Using Xray film with its wangy or elastic spring steel quality very much like that of the marine aluminium sheeting of the definitive boat, I played around with various cuts into rectangles of it to produce nice shapes letting the cut surfaces slide over each other.

Having played around with xray film I moved on to using thin gauge steel.

The pattern was simply this: the length of the sheet is twice the width - it can be whatever you like - it's what I chose as it seemed to work out on xray film - the cuts in the bow end (the blunt end) allow the sheeting to slide over itself  to a point such that the bow profile from the side was 45degress, a concession to internal space and an appropriate attitude to oncoming water.
 Since the sheet is truly rectangular it is easy to be bilaterally very accurate in one's markings. The excess of the overlap that lies above the gunwale is trimmed off forward in the line of it aft. This produces a cusp or hollow at the top of the bow which is conveniently filled with a symetrical bi-ellipse to form a supra-prow. For geometrical reasons I never tried to fathom the top of this ellipse is a splendid starting point for decking of the model again forming along the length decking which is at right angles to the gunwhale side along the whole length. Thus the forward decking runs upwards quite markedly and and progressing aft become less so and eventually flat.

The working model was made from a single sheet of thin steel in a few hours.

Naturally I feel flat at the moment and feel I want to be shot of it all. But I have to look back at what I wanted when I started out and that was:
1. to determine that which is not intuitive being whether the tear drop profile so ever present in nature is useful in boat design and
2. whether origami like simplicity in metal bending can offer a easy-build yaght embracing this non-intuitive concept.
I read somewhere that the ultimate in boat design is one that leaves no wake - allowing that a wake represents wasted energy no one would disagree with that though the parameters of performance need defining. Yet in evolutionary terms the tell-tale nature of a wake giving the game away either for the prey or the predator-hunter would be an action packed situation and would suggest the reverse tear drop shape is also meant for speed. Of course how this speed will be affected by the shape will be a function of the fluid's viscosity, which should be low, and its density, which should be high, so as to allow the pressure head developed to be usefully, and that means quickly, redistributed in the post head section of the form to 'squidge' it forward and thus retrieve the initial energy expended.
A bath of mercury might be an ideal liquid satisfying these criteria if one's model was heavy enough not to be displaced onto the surface!
 To stand by a pond and watch a large koi near the surface give a single swish of its tail and no more than this to shoot it forward with not an iota of visible disturbance is exhilarating.
One might think that I should have been building a submarine but the physical mores apply to any fluid, liquid or gas and one would think therefore to an body that is part immersed. The immediate responder might be the termoil at the liquid/gas, water/air interface  would be better negotiated by a sharp leading edge - well this remains to be seen.
One of the outstanding features I found when testing the model is incomparably better directional stability when the craft was pushed - no great shakes of course when the motion comes from pulling - though - when towing any conventional craft through the water the tendency for it to rapidly drift from the line of pull is well known.
Perhaps mentioned earlier, the buoyancy of my craft being well forward will prevent or lessen the likelihood of it being a pitch poled from a following sea by this acting on the wider and larger surface and much more buoyant forward section. Also the fine entry of the stern and its lesser buoyancy must offer an easier helm to control.

Well here I| am with a 'too floaty boaty'. What to do? Well, one positive need is re-ballasting and one positive outcome from that will be to bring the water level in the engine well dangerously close to filling her with water from the inside. So, the engine and its well will have to go. That can be done quickly. The well can be removed completely or cut just above its junction with the hull thereby offering some purchase for future bracketing etc. Of course the central hole that provided the entry point for the propeller drive will have to be plated unless option* below is taken.
 Then what are my other options for propulsion for the craft? They have to be compatible with adding lots more ballast.
- put an inboard engine in and run a shaft aft and provide a propeller in a cutaway section just forward of the rudder.
- think about an electric motor/battery/generator set up inside the boat.
- attach an electric long shaft engine alongside(outside) aft and accept a bias whilst under power.
-* using the existing hole in the bottom of the hull for a long vertical well to accommodate a very long shaft electric 'outboard'.