One For The Engine Crew

Thats another Story
3rd August 2010, 19:49
could a ship/boat be designed to have a speed lets say 70 knots weather permitting that is. as i know next to nothing about what goes on down below. but could it be done say for a container carrier.john

Billieboy
3rd August 2010, 20:25
Depends on how many containers John, 70kts. is fast, twice as fast as the old QE. Gas Turbine driven Hydroplanes, in Italy, get up to 50kts. but that is BIG fuel costs.

Peter B
3rd August 2010, 20:31
Assuming we are talking displacement type hulls (as opposed to "speed boats", who lifts out of the water by planing):
In theory, perhaps. In reality; no!
Keep in mind that the propulsion power required for a given hull in a given load condition varies with the cube of the speed. Let's take an example:
Let's say a 176.000 DWT / 14.000 TEU container carrier goes 24 knots on 100.00 bhp (my guess, but not far from reality).
Increase the speed to 26 knots and the power required is 127.141 bhp.
Increase the speed to 32 knots and the power required is 237.037 bhp.
Increase the speed to 70 knots and the power required is 2.481.192 bhp (1,83 GW).
This is basic theory, of course. In reality I think it would be fairly inpredictably what would happen to a displacement hull that size if it moved at 70 knots.

makko
3rd August 2010, 20:38
It could be designed, John but would never be built as purely impractical - HUGE fuel costs, HUGE hull costs. Then again, imagine hitting say a 12 metre wave at 70 kts!
Rgds.
Dave

captainjohn
3rd August 2010, 20:53
My naval architecture classes are over 40 years ago, but for a displacement hull, speed is limited by "hull speed", which is roughly 1.34 X square root of the length on the waterline. Hull form changes the factor (called Froude's number) somewhat, but there reaches a point where adding power only burns more fuel - unless and until the hull planes.

Peter B
4th August 2010, 00:55
My naval architecture classes are over 40 years ago, but for a displacement hull, speed is limited by "hull speed", which is roughly 1.34 X square root of the length on the waterline. Hull form changes the factor (called Froude's number) somewhat, but there reaches a point where adding power only burns more fuel - unless and until the hull planes.
This is very interesting! What units should be used for speed and length, for the factor to be 1.34? Knots / Feet?

Ian J. Huckin
4th August 2010, 17:43
Another problem would be the hull form.

Take for example a reefer capable of 26 knots, in most cases the bow is very fine resulting in the vessels box section not being fully achieved until aprox 1/3 of the way back. Plus the larger machinery space requires that the ER bulkhead is further forward. This means that to get the best stowage this type of vessel would load a large proportion of break bulk, not even palletized.

Now I know container ships achieve good speeds but in tripling their speed I'm not too sure you could load even 50% of the below weather deck space available with containers due to the constrictions mentioned above. So the stowage factor would be very inefficient (with containers)

Just some extra considerations.....

Satanic Mechanic
4th August 2010, 17:49
Basically to answer your question in a word:

NAW

(K)

John Rogers
4th August 2010, 17:54
I have heard that the top speed of the Nuke carriers are very fast,in most document tables they never list it.


John.

Satanic Mechanic
4th August 2010, 18:09
Another problem would be the hull form.

Take for example a reefer capable of 26 knots, in most cases the bow is very fine resulting in the vessels box section not being fully achieved until aprox 1/3 of the way back. Plus the larger machinery space requires that the ER bulkhead is further forward. This means that to get the best stowage this type of vessel would load a large proportion of break bulk, not even palletized.

Now I know container ships achieve good speeds but in tripling their speed I'm not too sure you could load even 50% of the below weather deck space available with containers due to the constrictions mentioned above. So the stowage factor would be very inefficient (with containers)

Just some extra considerations.....

We could have individually powered containers - special streamlined shape called a STEU pronounced 'Stew' right and a really really big outboard engine with twistlock attachment.
We could strap a navigator with flying goggles to the front , all the engineer would need to do is pull the starting cord a few times until the outboard starts and point it in the right direction.

And thats how I got my caffeine this afternoon(==D)

MARINEJOCKY
4th August 2010, 18:49
SM, I am away to buy shares in Yamaha outboard corporation, sounds like a good idea.

as for the formula to find the best ship shape, try

Chinese production cost + shipping = to what Walmart are willing to pay

therefore,

Walmart cost minus chinese production cost = shipping

surfaceblow
4th August 2010, 20:17
I was under the impression that the cheapest and newest container ships are already being used. At least for the feeder service.

Pat Kennedy
4th August 2010, 20:26
I recall reading a few years ago, an article which detailed what appeared to be a serious Russian project to build 30.000 ton nuclear submarines designed to carry crude oil from Russia to Japan.
I dont remember how fast these would be, but I do know that military nuclear subs are very fast.
Ive not read any more about this, maybe it was found to be impractical for one reason or another.
Pat

surfaceblow
4th August 2010, 20:34
There was a similar SNAME paper on the use of submarines to ship LNG in pressurized tanks.

captainjohn
4th August 2010, 21:50
Peter B - Knots & Feet.

For example, SS United States length on the waterline was about 930 ft. Square Root is 30.495 X 1.34 = 40.86 kts. hull speed. However as one post points out, hull form (block & prismatic coefficients, wetted surface, etc) all factor in. The table of Froude numbers takes all these into effect for varying drafts to calculate max hull speed.

As I said, 1.34 is a rule-of-thumb number, or in engineering terms, a SWAG (scientific wild-a** guess).

Thats another Story
4th August 2010, 21:54
so do you all think we have reached the limit of ship technology as regard speed and yet the aircraft industry now make bigger and faster aircraft it was my grandson that posed the question to me and i had to tell him i didn't know but i know the men that do. john

captainjohn
4th August 2010, 22:03
John - Remember that 1.34 X Sq. Root of LWL is for displacement hulls. Semi-planing, SWATH, catamarans, etc. are all a whole different kettle of fish. The FAST ships that were proposed were semi-planing hulls with waterjet propulsion. The fact that they would have been economically questionable if not downright unfeasible seems to have doomed them.

As for diplacement hulls, if you want to go faster, build a bigger longer ship. A vessel of 1200 ft length on the waterline could thoeretically do 46.5 kts. It would pass everything except a bunker barge.

Macphail
4th August 2010, 22:14
"It would pass everything except a bunker barge.".
What direction, rushing to supply the dodgy fuel, or , rushing away after supplying the dodgy fuel.

(Smoke)

John.

Ron Stringer
4th August 2010, 22:15
John,

If it is speed across the water that your grandson is interested in, he needs to look at ground-effect vessels such as those on the following sites.

http://www.vincelewis.net/ekranoplan.html

http://en.wikipedia.org/wiki/Ground_effect_vehicle

John Rogers
4th August 2010, 22:26
John as to your ref to aircraft, Boeing and Pratt &Whitney just only last month tested a jet engine on a test aircraft,I have forgotten the speed that it reached but it equates to flying from LA in Cal to New York City in 45 min.

John

John.

John Rogers
4th August 2010, 22:31
Her you go John,show this to your grandson.

Pratt & Whitney Rocketdyne's Curtis Berger sat in the control room at Edwards Air Force Base in California and worried about all the things that could go wrong during the first flight of an experimental hypersonic jet.

The Air Force was testing a Boeing X-51A that promised to reach speeds of 4,500 mph, or six times the speed of sound. The jet was powered by an engine designed and built at Pratt's campus in northwestern Palm Beach County.

Among Berger's concerns: Would the vehicle remain stable at 4,000 mph? Would the engine melt?

The test, conducted Wednesday, was a success. Dropped from a B-52 flying at 50,000 feet, the unmanned Boeing X-51A's "scramjet" engine fired up and flew for two and a half minutes.

"There's so many things that can get you, and there's so many things that need to go right," said Berger, director of hypersonic programs at Pratt & Whitney Rocketdyne.

The experimental aircraft hit Mach 5, or about 3,750 mph. That's twice as fast as the speediest fighter jets can fly.

captainjohn
4th August 2010, 22:34
Her you go John,show this to your grandson.

Pratt & Whitney Rocketdyne's Curtis Berger sat in the control room at Edwards Air Force Base in California and worried about all the things that could go wrong during the first flight of an experimental hypersonic jet.

The Air Force was testing a Boeing X-51A that promised to reach speeds of 4,500 mph, or six times the speed of sound. The jet was powered by an engine designed and built at Pratt's campus in northwestern Palm Beach County.

Among Berger's concerns: Would the vehicle remain stable at 4,000 mph? Would the engine melt?

The test, conducted Wednesday, was a success. Dropped from a B-52 flying at 50,000 feet, the unmanned Boeing X-51A's "scramjet" engine fired up and flew for two and a half minutes.

"There's so many things that can get you, and there's so many things that need to go right," said Berger, director of hypersonic programs at Pratt & Whitney Rocketdyne.

The experimental aircraft hit Mach 5, or about 3,750 mph. That's twice as fast as the speediest fighter jets can fly.


Yes, but how many 40-foot containers can it carry?

Thats another Story
4th August 2010, 22:43
thanks ron its coming together now although he is only nine he is very intelligent{abit like his grandad?} and he seems to ask all the wrong questions to me anyway i think i have a young einstein on my hands he will go far i think.

david freeman
5th August 2010, 09:08
could a ship/boat be designed to have a speed lets say 70 knots weather permitting that is. as i know next to nothing about what goes on down below. but could it be done say for a container carrier.john
I remember my father in law during WWII operating in HMS in the navy said a message was sent to the fast layer Manxman in the Med to proceed to the channel at all haste, and I belive he said the speed quoted in the radio mesage was 58Knots. Maybe this is true: a little reseach may prove the point. So although this is not a box boat, the navy have considered such power/tonnage ratio's a long time ago.

Billieboy
5th August 2010, 11:47
Limit of ship design? I don't think so, at least not yet. The important future advances will be in nuclear power, as this will eliminate a large ammount of liquid fuel requirements.

chadburn
5th August 2010, 16:03
Economic "value" does not come into the equation when the Taxpayer is footing the bill for the Services fast craft, air or sea, the only restriction is the range of the onboard fuel and the ability to refuel mid air or at sea.

Ian J. Huckin
5th August 2010, 16:26
We could have individually powered containers - special streamlined shape called a STEU pronounced 'Stew' right and a really really big outboard engine with twistlock attachment.
We could strap a navigator with flying goggles to the front , all the engineer would need to do is pull the starting cord a few times until the outboard starts and point it in the right direction.

And thats how I got my caffeine this afternoon(==D)

...and don't forget the white silk scarf trailing in the wind!

Not too sure about the caffeine this morning, it seems to interfere with the brandy......

surfaceblow
5th August 2010, 16:36
Fastship got 40 million from the US government in 2004 to build few high speed vessels. The Vessels were suppose to be able to go 40 knots, have a 10,000 ton payload, using five gas turbines 335,000 hp.

So far there has been some PR releases and photo ops of the politicians handing the money over but I have not heard any thing of the company lately.

JamesM
5th August 2010, 17:05
John,

If it is speed across the water that your grandson is interested in, he needs to look at ground-effect vessels such as those on the following sites.

http://www.vincelewis.net/ekranoplan.html

http://en.wikipedia.org/wiki/Ground_effect_vehicle

Ron, Thanks for the info.links ..... absolutely fascinating .... I had no idea. But then again, I'm only an old slow-speed diesel man ... and getting slower by the minute!!

john richards
5th August 2010, 21:16
Re John Rogers post #9. Nuclear Powered Aircraft Carriers.USS Hornet was assigned to Apollo 11 recovery(tricky dickey) onboard, recovery area some 900 miles SSE of Hawaii, Hornet was some 13miles distance from actual splashdown. A reporter on one of naval vessels in the recovery area was broadcasting @ the time, Hornet went to Flankspeed narrowing the distance, the reporter said " That carrier must be doing Sh" transmission scrambled! The technology may already be here. Keep Hugging Them Trees.

Pat Kennedy
6th August 2010, 10:47
Re John Rogers post #9. Nuclear Powered Aircraft Carriers.USS Hornet was assigned to Apollo 11 recovery(tricky dickey) onboard, recovery area some 900 miles SSE of Hawaii, Hornet was some 13miles distance from actual splashdown. A reporter on one of naval vessels in the recovery area was broadcasting @ the time, Hornet went to Flankspeed narrowing the distance, the reporter said " That carrier must be doing Sh" transmission scrambled! The technology may already be here. Keep Hugging Them Trees.

USS Hornet had a top speed of 33 knots, she was powered by four Westinghouse steam turbines delivering 150.000 shp.
One of my uncles who had been born and raised in the US was a rating on Hornet and was immensely proud of his ship and her part in the Apollo missions. She is now a museum ship moored at Alameda Ca.
Regards,
Pat(Thumb)