Oheka II: Difference between revisions
Schnellboot |
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Capable of 34[[knots]] top speed, she became the blue print for the [[German Navy]]'s [[Schnellboot]]. |
Capable of 34[[knots]] top speed, she became the blue print for the [[German Navy]]'s [[Schnellboot]]. |
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==Background== |
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After the [[Treaty of Versailles]], most of Germany's military production was severely curtailed. Small patrol craft, however, were not. The S-boote can trace their lineage back to a private motor [[yacht]]—a 22-ton-displacement, 34-knot craft called ''Oheka II'', which had been built in 1927 for a wealthy financier and patron of the arts, [[Otto Kahn]], by the German [[shipbuilding]] company [[Lürssen]]. |
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This design was chosen because the theatre of operations of such boats was expected to be the [[North Sea]], [[English Channel]] and the [[Western Approaches]]. The requirement for good performance in rough seas dictated the use of a round-bottomed displacement hull rather than the flat-bottomed planing hull that was more usual for small, high-speed boats. Lürssen overcame many of the disadvantages of such a hull and, with the Oheka II, produced a craft that was fast, strong and seaworthy. This attracted the interest of the German Navy, which in 1929 ordered a similar boat but fitted with two torpedo tubes. This became the S-1, and was the basis for all subsequent S-boote. |
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After experimenting with the S-1 the Germans made several improvements to the design. Small rudders added on either side of the main rudder could be angled outboard to 30 degrees, creating at high speed what's known as the [[Lürssen]] Effect.<ref>{{cite book | last = Saunders | first = Harold E. | authorlink = | coauthors = | title = Hydrodynamics in ship design, Volume 1 | publisher = Society of Naval Architects and Marine Engineers | date = 1957 | location = | url = | doi = | id = | isbn = 9991405712 | page = 586}}</ref> This drew in an "air pocket slightly behind the three propellers, increasing their efficiency, reducing the stern wave and keeping the boat at a nearly horizontal attitude".<ref>{{cite web | last = | first = | authorlink = | coauthors = | title = Schnellboot! An Illustrated Technical History - Design, Manufacture and Detail | work = | publisher = | date = | url = http://www.prinzeugen.com/DesignManufacture.htm | doi = | accessdate = Dec 16, 2009}}</ref> This was an important innovation as the horizontal attitude lifted the stern somewhat, allowing even greater speed, and the reduced stern wave made S-boats harder to see, especially at night. |
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==Background== |
==Background== |
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http://www.richardstokowski.de/luerssen1.html |
http://www.richardstokowski.de/luerssen1.html |
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==Input1== |
==Input1== |
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The attention of the German Navy was drawn to Oheka II , a highly innovative luxury motor yacht built in 1927 by the German boatyard Luerssen for a Jewish banking tycoon who emmigrated to the United States from Germany. The name "Oheka" originated from a monogram of its owner's name, Otto HErmann KAhn. It's round bottomed hull was 22.5 m long, and displaced 22.5 tons. It reached a top speed of 34 knots, making it the world's fastest boat in its class. There is no basis in fact for the common misconception that Oheka II was a "rum runner" used for smuggling. |
The attention of the German Navy was drawn to Oheka II , a highly innovative luxury motor yacht built in 1927 by the German boatyard Luerssen for a Jewish banking tycoon who emmigrated to the United States from Germany. The name "Oheka" originated from a monogram of its owner's name, Otto HErmann KAhn. It's round bottomed hull was 22.5 m long, and displaced 22.5 tons. It reached a top speed of 34 knots, making it the world's fastest boat in its class. There is no basis in fact for the common misconception that Oheka II was a "rum runner" used for smuggling. |
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Revision as of 17:29, 13 May 2010
| Class overview | |
|---|---|
| Name | Oheka II |
| Builders | Lürssen |
| Completed | 1 |
| Active | 0 |
| General characteristics | |
| Type | yacht |
| Displacement | 22.5 tonnes (22,500 kg) |
| Length | 22.5 metres (74 ft) |
| Propulsion | 3 x Maybach VL2 V-12, also used in Zeppelins |
| Speed | 34 knots |
Oheka II was a private motor yacht built for German investment banker Otto Hermann Kahn by Lürssen in 1927.
Capable of 34knots top speed, she became the blue print for the German Navy's Schnellboot.
Background
After the Treaty of Versailles, most of Germany's military production was severely curtailed. Small patrol craft, however, were not. The S-boote can trace their lineage back to a private motor yacht—a 22-ton-displacement, 34-knot craft called Oheka II, which had been built in 1927 for a wealthy financier and patron of the arts, Otto Kahn, by the German shipbuilding company Lürssen.
This design was chosen because the theatre of operations of such boats was expected to be the North Sea, English Channel and the Western Approaches. The requirement for good performance in rough seas dictated the use of a round-bottomed displacement hull rather than the flat-bottomed planing hull that was more usual for small, high-speed boats. Lürssen overcame many of the disadvantages of such a hull and, with the Oheka II, produced a craft that was fast, strong and seaworthy. This attracted the interest of the German Navy, which in 1929 ordered a similar boat but fitted with two torpedo tubes. This became the S-1, and was the basis for all subsequent S-boote.
After experimenting with the S-1 the Germans made several improvements to the design. Small rudders added on either side of the main rudder could be angled outboard to 30 degrees, creating at high speed what's known as the Lürssen Effect.[1] This drew in an "air pocket slightly behind the three propellers, increasing their efficiency, reducing the stern wave and keeping the boat at a nearly horizontal attitude".[2] This was an important innovation as the horizontal attitude lifted the stern somewhat, allowing even greater speed, and the reduced stern wave made S-boats harder to see, especially at night.
Background
Lürssen Oheka II 22.5m built 1927
22.5 m long, Displacement 22.5 tons. Speed of 34 knots
Pictureand information was taken from: [3]
Lürssen Oheka II 22.5m built 1927
22.5 m long, Displacement 22.5 tons. Speed of 34 knots
Picture was taken from:
http://www.richardstokowski.de/luerssen1.html
Input1
The attention of the German Navy was drawn to Oheka II , a highly innovative luxury motor yacht built in 1927 by the German boatyard Luerssen for a Jewish banking tycoon who emmigrated to the United States from Germany. The name "Oheka" originated from a monogram of its owner's name, Otto HErmann KAhn. It's round bottomed hull was 22.5 m long, and displaced 22.5 tons. It reached a top speed of 34 knots, making it the world's fastest boat in its class. There is no basis in fact for the common misconception that Oheka II was a "rum runner" used for smuggling.
In Oheka II, Luerrsen overcame many of the drawbacks of the round bottomed displacement hull. The boat ploughed through the water by the brute force of three 550hp Maybach engines. The composite use of wood planks over alloy frames reduced weight. The innefficient tendency for round hulls to "squat" stern-down in the water at high speeds was counterbalanced by a hull form that flattened towards the stern, providing hydrodynamic lift where it was needed.
Oheka II's combination of speed, strength and seaworthyness was exactly what Naval command wanted. In November 1929, Luerssen was given a contract to build a boat to the same basic design, but with two torpedo tubes on the forecastle, and a slightly improved top speed. It was to become S-1, the Kriegsmarine's first Schnellboot and the basis for the all other S-Boats built during World War 2.
Oheka II was powered by 3 Maybach VL2 engines. These were V-12 engines also used in Zeppelins.
Input2
The technical history of the S-Boat is a tribute to the imagination, determination and resourcefulness of German engineers. Although the treaty of Versailles was meant to prevent Germany from taking up arms in a war of aggression, its practical effect was to stimulate an ingenious and modernistic arms development program. Turning obstacles into advantages, German engineers designed weapons which both outwitted the restrictions of the Versailles treaty and capitalized on new technologies and tactics that could enable a small, lightly equipped nation to defeat a more powerful but anachronistic enemy. The rapid defeat of France in 1940, despite its overwhelming numerical superiority over Germany in weapons and troops, was total vindication of this program.
The S-Boat is a classic example of Germany's Versailles-influenced weapons engineering. Focusing on a boat considered too insignificant by the Allies to be regulated by the treaty, the Germans created a scaled down warship well-suited for naval Blitzkrieg. Heavily armed and fast, it could inflict great damage on a larger enemy and escape unharmed. Its sturdy design showed great foresight into its future operational role and emphasised high quality over mass production.
From very the beginning of the torpedo boat program, German Naval Command required boats suited for combat in North Sea conditions. A series of trials with a broad variety of designs began in 1920 under cover of developing a fast "submarine chaser," Most initial programs concentrated on short planing hulls commonly used for speedboats. This surface skimming design is ideal for fast boats in calm waters but loses its chief advantage of effiency when waves slam the flat hull bottom. Furthermore, weight is a critical issue, and the irridescent plume of water created by a planing boat moving at high speed is visible over great distances at night.
In 1928, in light of these limitations and the dismal North Sea weather, Naval command elected to concentrate strictly on a round bottomed displacement hull. Their attention was drawn to Oheka II , a highly innovative luxury motor yacht built in 1927 by the German boatyard Luerssen for a Jewish banking tycoon who emmigrated to the United States from Germany. The name "Oheka" originated from a monogram of its owner's name, Otto HErmann KAhn. It's round bottomed hull was 22.5 m long, and displaced 22.5 tons. It reached a top speed of 34 knots, making it the world's fastest boat in its class. There is no basis in fact for the common misconception that Oheka II was a "rum runner" used for smuggling.
In Oheka II, Luerrsen overcame many of the drawbacks of the round bottomed displacement hull. The boat ploughed through the water by the brute force of three 550hp Maybach engines. The composite use of wood planks over alloy frames reduced weight. The innefficient tendency for round hulls to "squat" stern-down in the water at high speeds was counterbalanced by a hull form that flattened towards the stern, providing hydrodynamic lift where it was needed.
Oheka II's combination of speed, strength and seaworthyness was exactly what Naval command wanted. In November 1929, Luerssen was given a contract to build a boat to the same basic design, but with two torpedo tubes on the forecastle, and a slightly improved top speed. It was to become S-1, the Kriegsmarine's first Schnellboot and the basis for the all other S-Boats built during World War 2.
Input3
the position of her engines (which actually are MAYBACH engines taken from the big airships like the "Hindenburg") are quite common in german designs of river-going, semi-gliding limousines like policeboats built until the late 50-ies.
I think the positioning of the engines up front counterballances the notion of round bottom-boasts to go "stern-down" when reaching hull-speed, but I am not shure, because im an amateur in boat design.
See also
References
- ^ Saunders, Harold E. (1957). Hydrodynamics in ship design, Volume 1. Society of Naval Architects and Marine Engineers. p. 586. ISBN 9991405712.
{{cite book}}: Cite has empty unknown parameter:|coauthors=(help) - ^ "Schnellboot! An Illustrated Technical History - Design, Manufacture and Detail". Retrieved Dec 16, 2009.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - ^ "Schnellboat". prinzeugen.com. Retrieved 2010-05-12.
External links
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