Waterline: Difference between revisions
m →Load line: remove double wikilink |
m warm/fresh water is *more* buoyant than cold/saline water isn't it? |
||
Line 1: | Line 1: | ||
'''Waterline''' refers to an imaginary line marking the level to which [[ship]] or [[boat]] submerges in the [[water]]. To an observer on the ship the water appears to rise or fall against the [[Hull (watercraft)|hull]] of the ship. |
'''Waterline''' refers to an imaginary line marking the level to which [[ship]] or [[boat]] submerges in the [[water]]. To an observer on the ship the water appears to rise or fall against the [[Hull (watercraft)|hull]] of the ship. |
||
Many factors determine the waterline. A heavy ship, or one heavily laden with cargo will submerge deeper in the water. Temperature will affect the level as warm water is |
Many factors determine the waterline. A heavy ship, or one heavily laden with cargo will submerge deeper in the water. Temperature will affect the level as warm water is more [[buoyant]] than cold water. Even the [[salinity]] of the water will affect the level because [[freshwater]] is more buoyant than salty [[seawater]]. |
||
For vessels with [[displacement hull]]s, the [[hull speed]] is determined by the waterline length. In [[sailing]] the length of the waterline can change as the boat [[Sailing#Heeling|heels]] and can dynamically impact the speed of the boat. |
For vessels with [[displacement hull]]s, the [[hull speed]] is determined by the waterline length. In [[sailing]] the length of the waterline can change as the boat [[Sailing#Heeling|heels]] and can dynamically impact the speed of the boat. |
||
Line 23: | Line 23: | ||
==See also== |
==See also== |
||
<!--*[[Lloyd's Rule]]--> |
<!--*[[Lloyd's Rule]]--> |
||
*[[Coffin ship]] |
* [[Coffin ship]] |
||
*[[Ballast tank]] |
* [[Ballast tank]] |
||
*[[Sailing ballast]] |
* [[Sailing ballast]] |
||
*[[Plimsoll shoe]] |
* [[Plimsoll shoe]] |
||
==External links== |
==External links== |
||
*http://www.oceansatlas.com/unatlas/uses/transportation_telecomm/maritime_trans/seafarer/seafarers/sea.htm |
* [http://www.oceansatlas.com/unatlas/uses/transportation_telecomm/maritime_trans/seafarer/seafarers/sea.htm UN ''Atlas of the Oceans'' article on waterline] |
||
*http://www.csgnetwork.com/h2odenscalc.html |
* [http://www.csgnetwork.com/h2odenscalc.html Water density calculator] |
||
{{water-stub}} |
{{water-stub}} |
Revision as of 13:24, 23 June 2006
Waterline refers to an imaginary line marking the level to which ship or boat submerges in the water. To an observer on the ship the water appears to rise or fall against the hull of the ship.
Many factors determine the waterline. A heavy ship, or one heavily laden with cargo will submerge deeper in the water. Temperature will affect the level as warm water is more buoyant than cold water. Even the salinity of the water will affect the level because freshwater is more buoyant than salty seawater.
For vessels with displacement hulls, the hull speed is determined by the waterline length. In sailing the length of the waterline can change as the boat heels and can dynamically impact the speed of the boat.
Load line
![](http://upload.wikimedia.org/wikipedia/commons/2/26/Plimsoll_line.png)
Many commercial ships have a symbol called a Load line painted on each side of the ship. This symbol, also called a International load line or Plimsoll line, marks the level to which the ship can be safely loaded. As cargo is brought on board the ship submerges and the symbol dips farther into the water.
Before these symbols were made compulsory many ships were lost due to overloading. Sometimes ships were intentionally overloaded in the hope of collecting insurance money. Ships carrying emigrants from Europe to America were also lost. Politician Samuel Plimsoll advocated for the improved safety standards and in his honor the mark bears his name.
The letters on the Plimsoll line have the following meanings:
- TF - Tropical Fresh Water
- F - Fresh Water
- T - Tropical Seawater
- S - Summer Seawater
- W - Winter Seawater
- WNA - Winter North Atlantic
These are used because changes in density between these different water masses affect ship buoyancy.