# Difference between revisions of "Scale models"

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Basically if you scale dimensions down by 25 and speed down by 5 things will happen at the same relative fraction of hull speed. If wave heights and wave lengths are scaled by 25 then wave speeds are also down by 5. So things work out well. However, in the model everything is happening 5 times faster. So if you see something tip back and forth every 2 seconds in the model it would be every 10 seconds in the full sized version. A 10 knott wind in the model is like a 50 knott wind in full scale. The important relationship between 25 and 5 is that 5 is the square-root of 25. Works for other numbers with this important relationship too. | Basically if you scale dimensions down by 25 and speed down by 5 things will happen at the same relative fraction of hull speed. If wave heights and wave lengths are scaled by 25 then wave speeds are also down by 5. So things work out well. However, in the model everything is happening 5 times faster. So if you see something tip back and forth every 2 seconds in the model it would be every 10 seconds in the full sized version. A 10 knott wind in the model is like a 50 knott wind in full scale. The important relationship between 25 and 5 is that 5 is the square-root of 25. Works for other numbers with this important relationship too. | ||

− | If you want to | + | If you want to simulate 8 foot waves with a period of 10 seconds while using a 1:25 scale model then waves for the model should be 4 inches high with a period of 2 seconds. Model waves 1 foot high correspond to 25 foot high real waves. Probably most modeling at 1:25 scale will be using between 4 inch and 1 foot waves. |

Mass scales with the cube of the dimension, so at 1:25 scale the mass in full scale prototype is 15,625 times larger than in a model. So if a model has 20 lbs of ballast the full scale will have 312,500 lbs of ballast. | Mass scales with the cube of the dimension, so at 1:25 scale the mass in full scale prototype is 15,625 times larger than in a model. So if a model has 20 lbs of ballast the full scale will have 312,500 lbs of ballast. |

## Revision as of 15:12, 5 June 2009

Scale models for engineering studies can help evaluate seastead designs.

Basically if you scale dimensions down by 25 and speed down by 5 things will happen at the same relative fraction of hull speed. If wave heights and wave lengths are scaled by 25 then wave speeds are also down by 5. So things work out well. However, in the model everything is happening 5 times faster. So if you see something tip back and forth every 2 seconds in the model it would be every 10 seconds in the full sized version. A 10 knott wind in the model is like a 50 knott wind in full scale. The important relationship between 25 and 5 is that 5 is the square-root of 25. Works for other numbers with this important relationship too.

If you want to simulate 8 foot waves with a period of 10 seconds while using a 1:25 scale model then waves for the model should be 4 inches high with a period of 2 seconds. Model waves 1 foot high correspond to 25 foot high real waves. Probably most modeling at 1:25 scale will be using between 4 inch and 1 foot waves.

Mass scales with the cube of the dimension, so at 1:25 scale the mass in full scale prototype is 15,625 times larger than in a model. So if a model has 20 lbs of ballast the full scale will have 312,500 lbs of ballast.

If you shoot video of a 1:25 scale model and slow it down by 5 then you can watch it as if your model was full scale and things were in real time.

## External links on scale modeling

* Wikipedia Similitude (model) * Wikipedia Similitude of ship models * Wikipedia Ship model basin * Wikipedia Response amplitude operator * Wikipedia Port Revel Shiphandling Training Centre

## Related

* Wikipedia Ship motions * Wikipedia Seakeeping * Wikipedia Ship stability * Vince Cate Models * Low Cost Wave Tank

## Computer modeling

* Ultramarine on boat modeling *blender

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Materials |
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Low Cost Wave Tank · Scale models · Wind Loads · Seasteading Software |

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