Logic in different length hulls

The Class 40 site might help? Seems like overhangs are also begging a question here
? (For example, is the 30 square meter bow (stern) a type of wave piercing strategy while retaining light air ability? I think one could argue Malizia had more bow overhang than the rest of the fleet, which worked downwind in the big stuff, but at the expense of LWL- gobs of sail area can make up for that in the light, as has been remarked, but with that comes longer masts, and more stuff up in the air which have their own influence in waves.)

 

"Where is the evidence that (1) a scow doesn't also have its C of G forward of the CF"

None

Buuuut it has a bow that resists sinking (Pitch) from a hydro-Static point of view

And

a bow that produces hydro-Dynamic Vertical lift force

And

it is a bow that produces no or very little Lateral hydro-dynamic force.

"and (2) that having the C of G forward of the CF is inferior overall?"

A sharp bow + center of gravity forward of the center of Flotation = hydro-dynamic disaster for crossing an ocean with Downwind Waves.

 

In a rational world, somewhere far away in this galaxy, sailboats would be rational based on available knowledge; but since we live where we live, very wide bows are welcome.

 

I found the answer in the Summa Theologica:

Summa Theologica - Wikipedia https://en.m.wikipedia.org/wiki/Summa_Theologica

Question: Could "Deus" have made a world suitable to achieve the end foreseen by divine providence, could "Deus" have made things right? Could "Deus" have done better

Answer: No, because if "Deus" obeyed reason or reasons it would no longer be "Deus".

I almost fell off my chair: "Deus" made this world as he pleased, without obeying anything, pure irresponsible whim.

---

And the worst thing is that it is quite logical:

at one end a small, good and obedient child. And at the other extreme someone so powerful that he obeys nothing and no one: power-absolute-that-does-not-give-explanations.

 

This was far more interesting than any debate on bow shapes could possibly be.

 

What "well balanced old classics"? Contemporary reports of many old classics (ie Dorade, Nina) state that they weren't well balanced when driven hard.

As someone who sails windsurfers, surfs surfboards and sails high-performance small craft I'm familiar with pics of canoes surfing (and with surfing on racing surf skis) I'm familiar with moving the CLR aft. However as noted earlier, that (1) doesn't require a scow bow and (2) even if a scow improves downwind directional stability in waves that is merely one of the many facets of sailboat performance and therefore as noted a scow can be an inferior craft overall.

There's plenty of conventionally-bowed boats that handle very well downwind; in fact some top designers felt that a fine sectioned Vee bow, which produces little dynamic lift and is almost the opposite to a scow bow, was the best shape for high speed downwind control. Here's a vid of such a design performing very well when driven hard - notice how little helm movement is taking place;



"Surf gliding" is just "surf riding" in bigger waves and as surfers and windsurfers will tell you, there's no step change between the two.

 

With large waves is when the hydrodynamic misbehavior is manifested.

The sailboat, like a wild bull, managed to eject the entire crew and was picked up by a Portuguese air force helicopter at the limit of its autonomy.

It is a reality that in many cases more numbers are made to make a washing machine than at the time of making a sailboat.

The sailboat after ejecting the crew with its hydrodynamic misbehavior ... tacked and crossed the Atlantic Ocean alone

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"Surf gliding" is just "surf riding" in bigger waves

E x a c t l y



(0.6 Froude and Big Wave)

"Surf gliding" and "Surf riding"



(0.5-0.6 Froude)

(Hydrodynamics Forces in Newtons)

 

My pretty little girl

If someday I have money for my pretty girl I will put some letters on the side of her that say:

Surf gliding is just surf riding in bigger waves

 

What changes is the calculation:

Around Froude 0.5-0.6 you have to distinguish between Vector A and Vector B, then at higher speed the two Vectors are the same Vector, and later at higher speed in addition they are joined to the HydroStatic Vector as in Savitsky 1964

I love the slogan and I am enthusiastic about it:

Surf gliding is just surf riding in bigger waves

 

Definitely the sport of preference for downwind cruising sailors.

 

-Why they launched a Mayday

-Because they were very scared

-Why they were very scared

-Because the yacht's misbehavior was very scary

 

Why the yacht misbehaves

Let's see, let's go by parts

The first thing to understand is that the Force of the Earth is enormous compared to the Force of the Wind.

Sailboats are or were heavy craft to sail powered by a Force of 3-4-5% of their Displacement, and with big Waves the Earth Force can propel it with a Force of 20% (!) of the Displacement.

 

In the curves of the so-called 'residual resistance' we see graphically and literally the wave of the hull and the wall of resistance created against which the sailboat crashes: on the one hand the hull piles up a mountain of water at the bow and, on the other hand, creates a hole or sinkhole where the stern falls off.

With one, two or three million dollars there is a very simple solution: we buy a huge Length and reduce D/L to for example 60

 

The problem we face is how to overcome the bow wave and so to speak give an outlet to the great Force of 20% of the Displacement: the Force of the Earth that wants to accelerate the sailboat to a Speed it was not used to and for which it was not designed.

The worst part of the case is that part of that Resistance is transformed or can be transformed into ...

a huge side force at the bow.

 

Suppose that in pleasant conditions sailing upwind in a nice light summer breeze ...

Max Michael Munk Moment ... =

2 x Leeway/Yaw (radians) x Dynamic Pressure (q) x Displacement (cubic meters) x 0.8

Moment de Munk — Wikipédia https://fr.m.wikipedia.org/wiki/Moment_de_Munk

...