[alloyed2sea]

..., then boats!
100ft+
30knots+
OK?

[alloyed2sea]

Gentry Eagle!
Designed by Peter Birkettto to win the Blue Riband in 1989 and built by Vosper Thornycroft, Ltd - she's 112 feet and topped out at almost 70 knots.
Relaunched as a yacht in 1992, she now travels the seas at a more leisurely 50+ knots in a style all her own.

[YachtForums]

Richard Branson's Virgin Atlantic Challenger II. 72 Feet, aluminum and gulps more fuel than a 3rd world country.

[YachtForums]

One more pic. Branson must hold more records in a variety of different transportation forms than anyone. Doncha love it!

[alloyed2sea]

...., Destriero!

Designed by Donald L. Blount and Associates (DLBA) in conjuction with the French firm CMN, and built by Fincantieri (Italy) in 1989.
She's 67 m long, 13 m wide, 50.000 horsepower, 110 Km/h maximum speed.
IN English thats:
220 ft, 65 knots!!
Winner Blue Ribband - 1992. To do this, she covered the 3,106 miles from New York's Ambrose Point Light to England's Bishop Rock Lighthouse in 55 hours without refueling while averaging 53 knots for the entire trip.

UPDATE: Hull form now being used by LockheedMartin to fulfill the US Navy's Littoral Combat Ship requirement. Your tax dollars at work!!!

[Donald Blount]

Originally Posted by alloyed2sea

...., Destriero!

Designed by Donald L. Blount and Associates (DLBA) in conjuction with the French firm CMN, and built by Fincantieri (Italy) in 1989.
She's 67 m long, 13 m wide, 50.000 horsepower, 110 Km/h maximum speed.
IN English thats:
220 ft, 65 knots!!
Winner Blue Ribband - 1992. To do this, she covered the 3,106 miles from New York's Ambrose Point Light to England's Bishop Rock Lighthouse in 55 hours without refueling while averaging 53 knots for the entire trip.

UPDATE: Hull form now being used by LockheedMartin to fulfill the US Navy's Littoral Combat Ship requirement. Your tax dollars at work!!!

What more do you know about Destriero?

[AMG]

Hello Donald,

Nice to see you as a member here! Since you probably know more than all of us together on Destriero, I would like to ask you two things:

She is claimed to have a semi-displacing hull. By definition, how can she be semi-planing in over 60 knots and what would be the difference if she had a planing hull? It has always puzzled me...

Secondly. Is the Yacht Club Costa Smeralda still the owners and what has happened or will happen to her in the future?

With regards
Lars

[alloyed2sea]

Originally Posted by Donald Blount

What more do you know about Destriero?

Can relate to you information concerning hull certification as a ship, satisfaction of insurance requirements, and crew selection & training.
But you know all of this, no?
Eric

[Donald Blount]

Originally Posted by AMG

Hello Donald,

Nice to see you as a member here! Since you probably know more than all of us together on Destriero, I would like to ask you two things:

She is claimed to have a semi-displacing hull. By definition, how can she be semi-planing in over 60 knots and what would be the difference if she had a planing hull? It has always puzzled me...

Secondly. Is the Yacht Club Costa Smeralda still the owners and what has happened or will happen to her in the future?

With regards
Lars

Destriero was only operated under charter by the Yacht Club Costa Smeralda. The vessel is owned by Bravo Romeo Limited.

Semi-dislpacement, as I use the term, represents the technology relating to the hydrodynamic speed range in combination with its displacement whereby the vessel's weight support is approximately 50% by buoyancy and 50% by dynamic lift. I do not believe that transverse section shape - round bilge, double chine or hard chine - should be descriptors of planing,semi-planing, semi-displacement or dislpacement hydrodynamics.

[Donald Blount]

Originally Posted by alloyed2sea

Can relate to you information concerning hull certification as a ship, satisfaction of insurance requirements, and crew selection & training.
But you know all of this, no?
Eric

Yes! I only asked the question out of curiosity. Your interests seem to be very broad; from classics to the very modern and I was exploring to see if you might have some Destriero knowledge which would indicate that you might be a good resource as a technology detective.

By the way, Desrtiero was a most gratifying experience.

[AMG]

Thank you for this explanation. I am not sure I understand it completely, since Destriero had a fuel load of almost half her displacement and must have used more than 50 % dynamic lift most of her transatlantic journey?

But in general terms I understand what you are saying, that a hull can be considered semi-displacement regardless of details like chine and V-shape.

For me, a semidisplacement hull is almost the same as a displacement hull, with the difference that it has a straight cut off stern which allows the hull to release the water and add speed but still not with a shape allowing it to plane.

This is why I bought the idea of Destriero as a semidisplacement yacht since her dimensions in a multiple maybe allowed her to go 60 knots without planing?

I have a lot of information on her but nothing that really explains why she is called semidisplacement and not considered a planing yacht.

Finally, Bravo Romeo must stand for Blue Riband, or?

/Lars

[Donald Blount]

Originally Posted by AMG

Thank you for this explanation. I am not sure I understand it completely, since Destriero had a fuel load of almost half her displacement and must have used more than 50 % dynamic lift most of her transatlantic journey?

But in general terms I understand what you are saying, that a hull can be considered semi-displacement regardless of details like chine and V-shape.

For me, a semidisplacement hull is almost the same as a displacement hull, with the difference that it has a straight cut off stern which allows the hull to release the water and add speed but still not with a shape allowing it to plane.

This is why I bought the idea of Destriero as a semidisplacement yacht since her dimensions in a multiple maybe allowed her to go 60 knots without planing?

I have a lot of information on her but nothing that really explains why she is called semidisplacement and not considered a planing yacht.

Finally, Bravo Romeo must stand for Blue Riband, or?

/Lars

The corporate name Bravo Romeo Limited has no dual meaning.

[CaptPKilbride]

I had always thought that the major difference between the two was in their resistance curves?

I percieved that a semi-displacement hull would have the sharp transom, allowing water to flow cleanly off the transom, and with more and more horsepower the hull would go faster to a certain point. This point being faster than a displacement hull with its theoretical hull speed limitation (1.44 x square root of LWL). Once the semei-displacement hull reached this "sweet Spot" in it's resistance curve, it takes exponentially more horsepower to produce speed gains given the same displacement.

And conversely, I thought that true planing hulls would produce more linear speed increases with increased horsepower (again given the same displacement)

Am I on the right track? Or was my perception off base.

By the way, Mr. Blount, I love what your company has done with the hull design and performance of the Rybovich sportfishing yachts !!

[Donald Blount]

Originally Posted by CaptPKilbride

I had always thought that the major difference between the two was in their resistance curves?

I percieved that a semi-displacement hull would have the sharp transom, allowing water to flow cleanly off the transom, and with more and more horsepower the hull would go faster to a certain point. This point being faster than a displacement hull with its theoretical hull speed limitation (1.44 x square root of LWL). Once the semei-displacement hull reached this "sweet Spot" in it's resistance curve, it takes exponentially more horsepower to produce speed gains given the same displacement.

And conversely, I thought that true planing hulls would produce more linear speed increases with increased horsepower (again given the same displacement)

Am I on the right track? Or was my perception off base.

By the way, Mr. Blount, I love what your company has done with the hull design and performance of the Rybovich sportfishing yachts !!

Thanks for your kind words about the Rybovich sportfishing boats.

You are on the right path. Hulls designed in a speed range where the vessel's weight is, for the most part, supported by buoyancy will have the aft end of it's hull lines buttocks curving upward toward the water's surface at the transom. This minimizes hull resistance below hull speed. If you try to power a displacement hull to higher than hull speed, the resistance increases rapidly.

As semi-displacement, semi-planing or planing speeds become a design requirement, the aft hull buttock shape must become straight, possibly with some hook (only for hump speeds) in order for the hull to begin to rise up relative to the surface of the water (not squat).

Using the square root of LWL x a constant multiplier (you used 1.44) is a representative way to describe relative boat speed for displacement vessels, but other factors become important for describing comparative speeds of different size boats when dynamic lift provides a significant component of support for the boat's weight.

For a relative example, Destriero at 60 knots has V/(square root of LWL) = 4.28 which would be the same as a Rybowich with LWL = 60 ft making a speed of 33 knots. A Rybovich of this size operates near 40 knots which would be V/(square root of LWL) = 5.16. In a relative hydrodynamic dimensionless speed comparison the sportfishing boat at 40 knots requires higher speed hull form technology than did the much larger Destriero design operating at 60 knots.

[YachtForums]

Keeping this thread going, I submit...

The New Millennium... 140 feet and 70 mph!

Power & Propulsion...

Twin Paxman 18Vp185 Diesels (5300 hp) Driving Vectored Lips Waterjets
Twin Lycoming Jet Turbines (4700 hp) Driving One-Fixed Lips Waterjets

(there's no replacement for displacement!)