How to Design a modern Yacht

The autopilot of the "Baroudeur" had, so to speak, the same brain as a crystal radio

Crystal radio - Wikipedia https://en.m.wikipedia.org/wiki/Crystal_radio

This ("Baroudeur" Surfing with total Control) is a really beautiful case, which once again confirms what Andrw Claughton saw in the Southampton wave tank and which fits with the theoretical models that we can build to numerically emulate the issue and understand it

 

(Speed and Time)

The sailboat could have capsized 3-4 times or 30-40 times in a 48 hour period

Because instead of being propelled by about 400 Newtons of Sail Force it was propelled by those 400 Newtons plus 4000-6000 Newtons of almighty Earth Force

 

Why it didn't capsize

Due to its Hull Attitude bow up and stern down when accelerating: high vertical pressure at the bow and low pressure at the stern, a large amount of low pressure

Good initial Yaw control and a Hull Attitude that allowed it to free itself from the wall of resistance and very destabilizing resistance against which it would have crashed if the wave raised the stern and sank the bow

Here in this video we see an old merchant ship subjected to an impossible speed; but which allows us to visualize in a graphic way the low pressure, the suction, created at the stern:

 

The Hull Attitude

The Hull Attitude, the stern down and the bow up, is the key to Surfing because it allows the sailboat to free itself from a wall of resistance and not crash into that wall of resistance and at the same time this attitude of the hull greatly improves Yaw control.

 

2 Tons sailboat and big Waves

Graphic comparison between

(1) the force of the sails, almost an insignificant speck of dust compared to

(2) the monstrous Force of the Earth: Newtons = mass in kilograms x 9.8

 

Time and again, here and there, there is talk of how to reduce the speed of a yacht:

series drogue size and count - Cruisers & Sailing Forums https://www.cruisersforum.com/forums/f122/series-drogue-size-and-count-262635.html

In the real world, there is talk of slowing down yachts

Why ?

the answer is obvious but almost no one wants to hear the truth: most sailboats/yachts are a hydrodynamic disaster waiting for bad weather to manifest their bad behavior

 

That an old 300 D/L and 19.19 feet LWL sailboat reaches a peak speed of 20 knots is not to stay looking at the finger pointing at the moon, but at the moon: Surf Control, Pitch and Yaw Control, magnificent Dynamic behavior in the water/Hydro

Hydro Dynamic

---

But the term hydrodynamics is used by most people to refer to speed on 'flat ground', in water like an oil pond, because the whole approach is based on big ships or big competitions.

Nobody is interested in the question of small sailboats. But, of course, in very bad weather, 40-49 foot sailboats are small, because in these circumstances with Big Waves they are driven by the powerful Force of the Earth

 

The Scow is the ultimate consensus-building solution:

(no thinking, no studying, no reading, no pondering, just perfect)

almost impossible to get wrong: the bow doesn't sink, the bow forms a good lifting surface, and the bow doesn't produce large amounts of lateral high pressure

 

1979

The helmsman of the 46-foot yacht "Vanguard" of the Hong Kong Admiral Cup team lost his intense concentration "an instant" (Peter Bruce)

and the yacht capsized doing a 360-degree roll

---

a Bow + Roll/Heel + Yaw + Pitch

plus Velocity ...

can create a Huuuuge Force

Angle of Attack (AoA) = Bow half Angle + Yaw/Leeway



So the Scow is the great solution for those who do not want to think, reflect or study

As well as being in general a good solution

Long Live to the Scow

 

That's a speed of about five knots.

What offshore sailing have you done?

Why do you maintain this lie about a very slow 22 footer going 20 knots when the fastest 73' maxis of the time, driven hard by champion crews, could only go about 21 knots?

 

"Surf gliding is Surf riding in bigger Waves"

the Scow is a good solution but i think that is no strictly necessary

V and D: Sail Force and Drag

A and B: Dynamic pressure
H1 and H2: Static pressure
H: hydroStatic vector = H1 + H2
E: powerful Force of the Earth

 

150 D/L Surfboard Plywood Epoxy for a Traditionalist 19.64 feet

6 h Force 7: 7.5-9 knots --- 14 Knots
24 h Force 7: 7.5-9 knots --- 18 Knots

"Surf gliding is Surf riding in bigger waves"

 

IMOCA Hugo Boss has the mast a little further aft than the mast position on my surfboard; but the leading edge of the keel on my surfboard is further aft: 60% LWL, "reculé" (set back) as the french designers of these big high-performance machines say

My design seems extreme and radical and yet is completely centrist because the primary center of a yacht, The Center of Flotation, even those Yachts from 1979-1999, is around 57% LWL

 

It seems that "wave piercing" bow has not been followed up on in latter boats, rather in fact, more spoon and lift.

 

0.60 Froude and Wave Force 7 without sail force and without hull wave to visualize more clearly and calculate more accurately the Dynamic trim of the hull