2006-08-24 14:15:35 · 9 answers · asked by titanictrainsboats 2 in Science & Mathematics ➔ Engineering
Yes, it is possible.
Hull speed for a displacement boat in knots is 1.34 * square root of the waterline length. 1000 feet at the waterline will mean the hull speed is 42.37 knots. I think your question can be restated: Can a displacement boat exceed hull speed?
Two options to get past hull speed.
1. Plane. Imagine a water ski boat. It can get past hull speed relatively easily because its hull planes on the water and is no longer subject to displacement hull speed. Planing boats can be relatively large (up to hundreds of feet), yet it is unlikely that a 1000 foot boat is going to be a planing boat, but possible.
2. Power. There are two waves that contribute to hull speed -- the bow wave and the quarter wave. The bow wave is the wave cresting at the front of the boat. The quarter wave is the secondary wave that is cresting somewhere behind the bow wave. The amplitude of these waves increases with speed and thus the crest of the quarter wave moves back as the speed of the boat increases. When the crest of the quarter wave is at the back of the boat, the hull has reached hull speed. If the boat exceeds hull speed then the crest of the quarter wave will be behind the hull, and the boat is now trying to climb the bow wave. Therefore, the power required to exceed hull speed is being used both to the push the boat forward through the water and also trying to lift it onto its own bow wave. I doubt that a 1000 foot long ship was ever built with enough power to exceed hull speed by more than a knot or two. Mainly I doubt it because it would be a terribly inefficient use of fuel for a precious few extra knots. However it is possible.
Check out the diagrams at http://www.sailnet.com/collections/articles/index.cfm?articleid=colgat006
2006-08-24 14:48:54 · answer #1 · answered by tke999 3 · 0⤊ 0⤋
Yes they can since Navy aircraft carriers need a certain amount of head wind for flight operations. Now granted most specs on carriers will say in excess of 30 knots, but from my personal experience of being on a cruiser we were able to do 36 knots on a steam turbine and the carrier in my battle group was able to move faster than my ship
2006-08-24 14:32:52 · answer #2 · answered by eric g 3 · 0⤊ 0⤋
No, for a couple reasons. Drag increases with the square of speed. A thousand foot long hull is going to have quite a bit of drag at 43 knots. The turbines would have to be huge. Vessels of that size (supertankers and aircraft carriers) are going to top out at 18 to 20 knots.
You'd have to lift the hull out of the water on hydrofoils to reduce the drag, and then you'd have amazing stresses on the vessel, not to mention the hydrofoils.
Theoretically it might be possible, but practically, it would be a nightmare.
2006-08-24 14:27:00 · answer #3 · answered by Wicked Mickey 4 · 0⤊ 0⤋
I don't see why not. The friction factor for just skin resistance drops as the length increases as well as the wave making resistance. A ship of 1000 feet in length at 40 knots has requires less power per ft of wetted surface than a ship 100 ft long at 38 knots.
2006-08-24 14:31:42 · answer #4 · answered by Roadkill 6 · 0⤊ 0⤋
Possible.
Most of todays cruise liners exceed1,000ft (300m) in length and reaches 25 knots. But they are not designed for speed. They are designed to carry lots of people and be energy efficient. They are also usually diesel powered.
The experimental U.S. Navy ship "Sea Fighter", a twin-hull ship can go 50 knots, but it is only 262 feet long. And it is diesel.
Russian alpha class submarines can go 40knots but they are nuclear powered and only 267ft also.
The drag depends more on the cross-sectional area than the length, so it is theorectically possible.
But steam turbine is hardly used as a means of transport. The steam turbines are usually used for making electricity. But I suppose it could be used to turn propellers instead of a dynamo.
2006-08-24 14:51:53 · answer #5 · answered by Kitiany 5 · 0⤊ 1⤋
Probably... seeing as how nuclear powered ships use steam turbines for propulsion... the steam comes from the reactor.
2006-08-24 14:21:39 · answer #6 · answered by Anonymous · 0⤊ 0⤋
Anything is possible with enough power. 43 knots probably involves having at least some level of partial aquaplaning, and not just displacement floating, but it could be done.
It will not be economical, though.
2006-08-24 14:20:14 · answer #7 · answered by Vincent G 7 · 0⤊ 0⤋
Initially, I would say yes. Steam engines are powerful. But then, I would have to ask the ship's displacement.
2006-08-24 14:18:13 · answer #8 · answered by Anonymous · 0⤊ 1⤋
Ask the U.S.Navy they are the ones with the answers on that one
2006-08-24 14:18:50 · answer #9 · answered by allan2uall 3 · 0⤊ 1⤋