Good Morning,
I would love for you to review this vital information that i wish to share with you.
It is something i stumbled upon from one of my directories for investors.
Best wishes,
John.
P:S; I've attached everything you need.Tuesday, August 29, 2017
Thursday, December 29, 2016
The Directional Stability of the Reversed Tear Drop Form
One of the more evident features of testing the models I used is that the directional stability, and by this I mean the inherent ability of the boat to keep to a course ie a straight line, when pushed or pulled through the water, is superb compared to the conventional situation when the front is the sharp end.
The reason for this at least twofold. In the first instance in any forward motion a sharp edge engages instantly on the conditions immediately - these will be conditions in the water and air combined but allowing that a hooly is not blowing and creating waves to hit and bias the transit of the bow through the water, it will be the underwater form, presence of any keel like structure and the draught of the boat. Secondly as a result the pressure differences in the water on each side of the bow will tend to deflect instantly and the bow waves that are thus created as direction of the craft changes, are, at the instant they are generated, equal but as the change in direction occurs the wave form generated on the opposite side to the new direction of travel, should stop that change in direction and oppose the change. But this doesn't happen. The vertical axial plane through the lubber line changes as and because the craft leans over out and away from the new direction (like a car going around a corner as opposed to a motor bike) and offers more of the craft's leading surface on that side and this and that the already generated bow wave further enables the change in direction. Effectively it will exaggerate the change - not too good if one is trying to keep a straight line in very bad conditions.
Where the front is bulbous or rounded but not bluntly square on, an area of raised pressure at the waters surface ( and in the air above ) is generated with forward movement of the craft and stays with the craft till it is dissipated at the maximum width of the craft and then provides, at least theoretically a moment or pressure gradient to squidge the craft forward. On the side to which the craft is turning the pressure wave sidles paste the point of maximum beam, which is well forward and creates a relative negative pressure effect on that side which will pull the hull to the opposite side and cause the hull to come back away from the direction of the turn.
The reason for this at least twofold. In the first instance in any forward motion a sharp edge engages instantly on the conditions immediately - these will be conditions in the water and air combined but allowing that a hooly is not blowing and creating waves to hit and bias the transit of the bow through the water, it will be the underwater form, presence of any keel like structure and the draught of the boat. Secondly as a result the pressure differences in the water on each side of the bow will tend to deflect instantly and the bow waves that are thus created as direction of the craft changes, are, at the instant they are generated, equal but as the change in direction occurs the wave form generated on the opposite side to the new direction of travel, should stop that change in direction and oppose the change. But this doesn't happen. The vertical axial plane through the lubber line changes as and because the craft leans over out and away from the new direction (like a car going around a corner as opposed to a motor bike) and offers more of the craft's leading surface on that side and this and that the already generated bow wave further enables the change in direction. Effectively it will exaggerate the change - not too good if one is trying to keep a straight line in very bad conditions.
Where the front is bulbous or rounded but not bluntly square on, an area of raised pressure at the waters surface ( and in the air above ) is generated with forward movement of the craft and stays with the craft till it is dissipated at the maximum width of the craft and then provides, at least theoretically a moment or pressure gradient to squidge the craft forward. On the side to which the craft is turning the pressure wave sidles paste the point of maximum beam, which is well forward and creates a relative negative pressure effect on that side which will pull the hull to the opposite side and cause the hull to come back away from the direction of the turn.
Tuesday, September 22, 2015
An update on Tuanella3 - the pontoon.
As previously mentioned the stability of Tuanella 3 was profoundly out of kilter and she road so high on the water as a finger tip could push her to one side or another - this despite a massive lead keel and sacks of aggregate against its sole.
.
This picture shows the water mark some 7 or so inches from the bottom.
She is really just sitting almost on knife edge.
The hull was of 2mm marine aluminium and this was patently too light. Although the cabin is of wood, perspex and aluminium section it was distant enough from the water line to aid toppling the craft.
Having decided at this stage to preserve the engine arrangement I set out to counter the stability with two outriggers. There were to be two but just making one for the moment is all I can manage. I have tried to arrange it so that it will fold up against the port side to aid transport and so, hopefully, all I shall have to do it lower it in the water and let the hinge and strut arrangement hold the pontoon in place. It is close to T3's hull but of a weight and buoyancy that should steady her.
Nothing of the gunwale fittings are attached here to T3 but the general idea of how she will lie is shown.
The general heftiness of the fabricated hinges and slides can be seen in the following.
Just a couple things of note about the fittings above: the double offset hinge rotates both on the hull and the pontoon. This is only at the stern end. Forward the hinge there rotates only on the hull.The attachment of both hinges is well above the envisage new water line. Not knowing quite where the pontoon will find its level the flexibility offered by the hinges will hopefully accommodate this. I expect the maximum displacement or draft of the pontoon to be about two inches in calm water.
There is a worry that when the craft is launched the weight of the pontoon will not be enough to offset the possibility of a tumble to starboard if there is rough water and wind from port side. I guess wearing a life jacket will be important.
.
This picture shows the water mark some 7 or so inches from the bottom.
She is really just sitting almost on knife edge.
The hull was of 2mm marine aluminium and this was patently too light. Although the cabin is of wood, perspex and aluminium section it was distant enough from the water line to aid toppling the craft.
Having decided at this stage to preserve the engine arrangement I set out to counter the stability with two outriggers. There were to be two but just making one for the moment is all I can manage. I have tried to arrange it so that it will fold up against the port side to aid transport and so, hopefully, all I shall have to do it lower it in the water and let the hinge and strut arrangement hold the pontoon in place. It is close to T3's hull but of a weight and buoyancy that should steady her.
Nothing of the gunwale fittings are attached here to T3 but the general idea of how she will lie is shown.
The general heftiness of the fabricated hinges and slides can be seen in the following.
Just a couple things of note about the fittings above: the double offset hinge rotates both on the hull and the pontoon. This is only at the stern end. Forward the hinge there rotates only on the hull.The attachment of both hinges is well above the envisage new water line. Not knowing quite where the pontoon will find its level the flexibility offered by the hinges will hopefully accommodate this. I expect the maximum displacement or draft of the pontoon to be about two inches in calm water.
There is a worry that when the craft is launched the weight of the pontoon will not be enough to offset the possibility of a tumble to starboard if there is rough water and wind from port side. I guess wearing a life jacket will be important.
Thursday, August 27, 2015
How Owls and The Tear Drop Design Are Connected.
On the bbc the other night a nature program on how owls fly without their flapping making a noise and alerting their prey.
The presenter highlighted the special features of their wing and compared them to a pigeon and a hawk. In the case of the owl it showed how feather 'tufting' absorbed sound and emphasised the fact that unlike the others it was a slow flying bird.
I think the pigeon was ill - placed in that group as it is not a hunting bird but more a seed herbivore. It needs speed however to escape predation and so perhaps its inclusion was permissible.
The differences in body shape were noted but the elephant in the room was that they did not stress how important that was in addition to the wing features.
What was so fabulous to see was the owl in flight, slowish, steady, infrequent flapping and mostly in descent and levelling off. What stood out was the shape of the owl in flight. Every feather adorning its marvellous face and neck standing vertical to present the blunt and non-streamlined presence that its face is and then this tapering very quickly to its sharp tail to present a true tear-drop form.
I contend that it is this as much or more than the wing form that enables it to course through the air silently and without ruffling the air it is in. This is easy to comprehend just visually. The broad wing spread of the owl announces it is designed for slow flight.
The presenter highlighted the special features of their wing and compared them to a pigeon and a hawk. In the case of the owl it showed how feather 'tufting' absorbed sound and emphasised the fact that unlike the others it was a slow flying bird.
I think the pigeon was ill - placed in that group as it is not a hunting bird but more a seed herbivore. It needs speed however to escape predation and so perhaps its inclusion was permissible.
The differences in body shape were noted but the elephant in the room was that they did not stress how important that was in addition to the wing features.
What was so fabulous to see was the owl in flight, slowish, steady, infrequent flapping and mostly in descent and levelling off. What stood out was the shape of the owl in flight. Every feather adorning its marvellous face and neck standing vertical to present the blunt and non-streamlined presence that its face is and then this tapering very quickly to its sharp tail to present a true tear-drop form.
I contend that it is this as much or more than the wing form that enables it to course through the air silently and without ruffling the air it is in. This is easy to comprehend just visually. The broad wing spread of the owl announces it is designed for slow flight.
Friday, August 14, 2015
Help required defining the geometry of Tuanella 3 - ? complex integrated conincal?
Tuanella 3 was made from a single sheet of aluminium. The remit was to have a hull like structure blunt (rounded) at one end and sharp at the other - subserving those fundamentals I hope to elucidate about the generality of most natural forms that find their way through a gas or fluid.
A thin sheet can be formed into a conical structure by bringing the ends of one side towards each other and the angle formed can be changed by overlapping those ends.
If the apex of the cone is closed and the overlap sealed then a container is generated. The standard laboratory funnel filter is made by indenting a disc of filter paper from a point on its circumference towards its centre and allowing the indent to overlap and lie flat on the cone so generated.
.............................................................
If an oblong sheet is cut anywhere along its length from its margins towards its centre anywhere a cone can be made. Choosing to do this in three places one can create a container which will float if the cut edges are sealed.
Unlike boats made from single sheets of metal where the sheet is sectioned and joined edge to edge
and generated angle at those joins the use of multiple cones results only flat and curved surfaces which in terms of boats makes for an aesthetic appearance.
Selectively cutting can produce many shapes with a range of cross-sectional profiles that approach
those seen in many boats with the sole of those shape varying from a rounded v to a flattish section that might be seen to offer a degree of bilge to the form.
A thin sheet can be formed into a conical structure by bringing the ends of one side towards each other and the angle formed can be changed by overlapping those ends.
If the apex of the cone is closed and the overlap sealed then a container is generated. The standard laboratory funnel filter is made by indenting a disc of filter paper from a point on its circumference towards its centre and allowing the indent to overlap and lie flat on the cone so generated.
.............................................................
If an oblong sheet is cut anywhere along its length from its margins towards its centre anywhere a cone can be made. Choosing to do this in three places one can create a container which will float if the cut edges are sealed.
Unlike boats made from single sheets of metal where the sheet is sectioned and joined edge to edge
and generated angle at those joins the use of multiple cones results only flat and curved surfaces which in terms of boats makes for an aesthetic appearance.
Selectively cutting can produce many shapes with a range of cross-sectional profiles that approach
those seen in many boats with the sole of those shape varying from a rounded v to a flattish section that might be seen to offer a degree of bilge to the form.
The general overall cross section is V and this offers a bilge that will plunge significantly before offering buoyancy. However if the hull is rotated laterally in the static situation that I propose for the catamaran then this plunge effect is diminished markedly and replaced with increased buoyancy and a tendency to plane. In the dynamic situation of a single hull driven by wind heeling will also rapidly reproduce this situation . Heeling will, of course reduce the directional stability the V section might offer but can't at least be countered somewhat if there are a pair of angled rudders. which is particularly good for the catamaran concept.
.....................................................................Tuesday, August 11, 2015
Some observations on the need for strength in hulls of catamarans.
I understand that one of the principle reasons the costs of catamarans is high related to the obvious ie there are two hulls. In the nature of any hull has to be the inherent strength by way of its shape to hold it shape and secondly retain attachments or resist separation of attachments like the keel, rudder, mast, engine, bulkheads. Not only do catamaran have over mono-hulls the spread of the load but especially when it comes to keels they mostly do without them stability being the mutual out-rigging of the other. If the underwater surface offers some directional form this too is a bonus .
I contend the reversed tear-drop form made in the single sheet manner I have described does this well as a mono hull but for the hulls of catamarans there can be another notable bonus. If the hull topsides are rotated inwards so as to make the outer sides nigh on vertical the increase in the free-board offered remarkable and with this rotation outwards of the bottom of the hull so too and significant increase in the boats stability. Of course the free-board of the inner sides is correspondingly reduced. This gunwales of these side now form the margins of the connecting pan like floor that will join them.
The deck is made from the 'roofing' that connects the outer gunwales.
The space that has been generated from doing this is quite staggering and all still without any intrusion of structures above the deck - pure central living space.
Geometrically the cross-section along its length is an isosceles trapezium (trapezoid in USA). Therein are inherent triangular derivatives that offer great strength here especially from the distance in height from the floor to the ceiling (deck).
In terms of offering a site for suspending a keel, fixed or lifting, placing the engine, chain lockers and workspace it is perfect aft wise and forward great for a mutual below deck dining and galley with immediate access to the hull containing the cabins, showers and heads. or otherwise it is perfect.
An above deck cabin and wheel house is easy to install between bulkhead and thus without structurally affecting the hull.
The internal rotation of the hulls means the forward 'flatness' of the sole become some v shaped offering more directional stability.
In the diagram I have treated each pair of hull identically by adding the two deck options and the two floor options . In each pair I have shown the inner side of the hull cut down to bring the floor down .
Even if this is not done in the lower pair the shaded area represents the gain over the upper pair and this is a feather off one and half times the cross section of one hull and this is without the curvature of the deck added in. Indeed a great increase in space and hopefully the movement of buoyancy outermost.
I contend the reversed tear-drop form made in the single sheet manner I have described does this well as a mono hull but for the hulls of catamarans there can be another notable bonus. If the hull topsides are rotated inwards so as to make the outer sides nigh on vertical the increase in the free-board offered remarkable and with this rotation outwards of the bottom of the hull so too and significant increase in the boats stability. Of course the free-board of the inner sides is correspondingly reduced. This gunwales of these side now form the margins of the connecting pan like floor that will join them.
The deck is made from the 'roofing' that connects the outer gunwales.
The space that has been generated from doing this is quite staggering and all still without any intrusion of structures above the deck - pure central living space.
Geometrically the cross-section along its length is an isosceles trapezium (trapezoid in USA). Therein are inherent triangular derivatives that offer great strength here especially from the distance in height from the floor to the ceiling (deck).
In terms of offering a site for suspending a keel, fixed or lifting, placing the engine, chain lockers and workspace it is perfect aft wise and forward great for a mutual below deck dining and galley with immediate access to the hull containing the cabins, showers and heads. or otherwise it is perfect.
An above deck cabin and wheel house is easy to install between bulkhead and thus without structurally affecting the hull.
The internal rotation of the hulls means the forward 'flatness' of the sole become some v shaped offering more directional stability.
In the diagram I have treated each pair of hull identically by adding the two deck options and the two floor options . In each pair I have shown the inner side of the hull cut down to bring the floor down .
Even if this is not done in the lower pair the shaded area represents the gain over the upper pair and this is a feather off one and half times the cross section of one hull and this is without the curvature of the deck added in. Indeed a great increase in space and hopefully the movement of buoyancy outermost.
Wednesday, April 1, 2015
A reiteration of aims
The idea that in nature, for the preservation of energy and to aid and avoid predation in any fluid, liquid or gas, the presence of a rounded front and pointed tail, is fundamental.
The sheer instability obvious in the mono-hull I built rather puts a single hull out of the picture in the matter of building a fast and cheaply built cruising sailing boat. But that fault, its lightness, may indeed be it's salvation when used as one of a pair in the building of a catamaran.
The success of catamarans on skids and thus low wetted surface areas was shown in the last America's Cup. Their instability however was also sadly demonstrated with the loss of life and it must have struck many as obvious that in heavy weather of any sort purchase on the sea and thus stability was going to be pretty precarious.
Here the use of two hulls, made similarly as the one before, from a single sheet of metal, means they can be absolutely identical and such reinforcements as needed on the sole of the hull or any other part can be identical and utterly flush as there is no 'belly or 3rd dimension' to it. Those reinforcements should leave no gap and riveting them in place with perhaps a thin lay of silicone filler should offer a very sound strengthening.
Here the use of two hulls, made similarly as the one before, from a single sheet of metal, means they can be absolutely identical and such reinforcements as needed on the sole of the hull or any other part can be identical and utterly flush as there is no 'belly or 3rd dimension' to it. Those reinforcements should leave no gap and riveting them in place with perhaps a thin lay of silicone filler should offer a very sound strengthening.
Subscribe to:
Posts (Atom)