Editing Lightship (section)

===Mooring===
[[Image:LV101 with Mushroom anchor.jpg|thumb|right|Lightship ''Portsmouth'' (LV-101) shows its mushroom anchor. It can be seen at downtown [[Portsmouth, Virginia]], and is a part of the Naval Shipyard Museum.]]

Holding the vessel in position was an important aspect of lightvessel engineering. Early lightships used [[Anchor#Danforth anchor|fluke anchor]]s, which are still in use on many contemporary vessels, though these anchors are prone to dragging, making their performance unsatisfactory in rough seas. 

Since the early 19th century, lightships have used [[Anchor#Mushroom|mushroom anchor]]s, named for their shape, which typically weigh 3 to 4 tons. The first lightvessel equipped with one was a converted fishing boat, renamed ''[[Pharos]],'' meaning lighthouse, which entered service on September 15th, 1807, near [[Inchcape]], Scotland with an anchor weighing 1.5 tons.<ref>{{cite book|last=Cadbury|first=Deborah|title=Seven Wonders of the Industrial World|url=https://archive.org/details/sevenwondersofin0000cadb|url-access=registration|year=2003|publisher=Fourth Estate|pages=[https://archive.org/details/sevenwondersofin0000cadb/page/79 79]|isbn=9780007163045 }}</ref> The introduction of cast iron anchor [[Chain|chains]] in the 1820s improved their effectiveness dramatically, with the [[rule of thumb]] being {{convert|6|feet}} of chain for every foot of water.