Simplified Froude-Krylov Force

A Pogo 2 for an Old Fogey

The bowsprit swings aft and reaches the Old Fogey's hands

But of course: he has to lift his rear end off the comfortable seat

A cruel design choice by the designer

 

Aren't you the designer?

 

Pogo 2

 

An improved Pogo 2 for an old fogey

+ Upwind sailing is easy to improve: 220 liters of water (American Express, 1979 MiniTransat winner) which is much more than the 750 liters of the Class 40, plus the 3/4 fractional rig is more versatile upwind

+ Keeping it stationary safely (and preventing it from capsizing like the IMOCA Hugo Boss) is also simple: lift the rudder blades out of the water and anchor in the sea with 100 meters of line

+ The issue of capsizing and righting the boat is drastically improved with a higher freeboard, a cockpit that doesn't become like a catamaran (!) and a fully enclosed mast without the silly superstition of ruining it by drilling holes in it. The effect of a fully enclosed mast is phenomenal on a small, ultralight boat

+ Surfing is the same or better from a safety/comfort point of view and with better Yaw control

+ Sink resistance is improved with plenty of watertight compartments and the bow compartments filled, as is now standard

+ Centering the mast, a rotating bowsprit, and comfortable rig are simple, a huge seat in a protected cockpit and the sailor close to the sailboat's fundamental centers

The only complicated part has been the hull engineering and weight control to match a Pogo 2

Obviously, the Pogo 2 with 15 knots of wind crosses the Atlantic faster because a young athlete hoists an astronomically sized gennaker; but that's irrelevant for a MiniTransat for an old sailor

I have no interest in speed... average speed, which is what wins in contests to see who can pee the farthest

I want my surfboard to surf at 14-20 knots because the Force of the Wind, the Force of the Sea (the Froude-Krylov Force) and the Almighty Force of the Earth ... demand it

... when the wind in January and Summer in the Atlantic is 20-25-30 knots

Azores High - Wikipedia https://en.wikipedia.org/wiki/Azores_High

 

From AI
No, the center of flotation (CF) is not the same as the center of buoyancy (CB). They represent different physical properties of a floating vessel: [1, 2, 3, 4]

• Center of Flotation (CF): The geometric centroid (center) of the waterplane area—the 2D surface area of the water where the ship breaks the surface. It acts as the pivot point (or hinge) for trimming and pitching.
• Center of Buoyancy (CB): The center of gravity of the submerged volume of water displaced by the hull. This is the point through which the upward buoyant force acts. [1, 2, 3, 4, 5

I wonder if Carlos is not aware. At rest, Gonzo, as you noted, the CB and CG are aligned vertically

 

"No, the center of flotation (CF) is not the same as the center of buoyancy (CB)"

---

Haha

I've spent thousands of pages saying that it would be good even for a modern sport yacht (like a Classic British Yacht) to place the center of Buoyancy (CB) at the center of Flotation or aft of the center of Flotation (CF)

If the center of Flotation of a yacht with a wide stern is at 58% LWL ...

where would you place the center of Buoyancy and the center of Gravity and the hydroDynamic center of the Keel

Thats the question



1 Ton WindSurfBoard Plywood Epoxy
Modern Sport Yacht
huuuge Wide Stern

CF: Center of Flotation: 58% LWL
Center of Buoyancy at rest/port: 60% [6] LWL

Center of Buoyancy Hull Trim +2° Bow Up 70% LWL [7]

CG: Center of Gravity: 62% LWL

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Of course, when stationary in port, the bow rises slightly until the CB moves to a position below the CG

 

The sailboat is so powerful that if it weren't for the hydrodynamic trim of the hull, the center of gravity would have to be moved a lot aft to withstand the force of the sails by taking on seawater in ballast tanks at the stern like an IMOCA.

 

Look

Look at the sailor position

The girl has shifted the center of gravity a lot towards the stern because she contributes a significant portion of the sailboat's weight.

Surfing ... We need to trim the hull bow-up for two related reasons:

1) to withstand the Force of the Sails with a huuuge lever arm and on a small, powerful, and lightweight boat, and

2) we need Angle of Attack to achieve hydrodynamic lift.

We need to raise the bow out of the water for raising the bow out of the water; this is a critical issue because the problem is circular: the better, the better, and the worse, the worse.

in a 1-3 Ton Sport Yacht/Sailboat the Hull Trim must be hydro-Dynamic Trim

In a dinghy, the crew trims the hull; but that can't be done in larger boats.

 

Apparently, according to Carlos that is not the case with surfboards. His drawing of a rectangle represents a design that is superior to anything that ever floated; according to Carlos.

 

Of course, on the other hand, it is necessary to ensure that the angle of attack is not too large: that is one of the many functions that a huge, wide stern fulfills on a modern sports yacht.

 

It's a very interesting interplay of forces

(A) HydroDynamic Lift at 0.60 Froude: approximately 3000 Newtons

 

If the center of Flotation of a modern yacht with a wide stern is at 57-58-59% LWL ...

Where would you place

(1) the center of Buoyancy
(2) the center of Gravity and
(3) the hydroDynamic center of the Keel ...

If your goal is safety and comfort

Thats the Question

Give me numbers and reasons

 

1 They are both the same. There are no options for a different location
2 It will be vertically aligned as the Laws of physics require
3 That depends on the rig

 

"it is necessary to ensure that the angle of attack is not too large:"

Modern sailboat or planing/semi planing hull?

 

Why build a powerful sports sailboat with the well-balanced design of a classic British yacht?

For the intellectual pleasure of doing things right, and for the practical advantage of not needing speed to handle the waves well.