Two questions regarding depth

Sean C · 02-12-18, 11:30 PM

Depths have been an integral part of coastal navigation for centuries. Sailors used a "lead line" as far back as the ancient Greeks and Romans. In addition to depths, the type of sediment on the sea floor was also catalogued. There was a cavity in the bottom of the weight, usually filled with tallow (rendered animal fat), which would pick up sediment upon hitting the bottom.

When in well-traveled coastal waters a sailor's lead line showed (for example) ten fathoms and sand, he would have a fairly good idea of where he was in relation to the coast. Admittedly, knowing the type of sediment below is not very useful in a submarine ... but moderately accurate depths would undoubtedly have been available for the entire period of their use.

02-12-18, 11:30 PM	#7
Sean C Grey Wolf Join Date: Jun 2017 Location: Norfolk, VA Posts: 923 Downloads: 12 Uploads: 2	Depths have been an integral part of coastal navigation for centuries. Sailors used a "lead line" as far back as the ancient Greeks and Romans. In addition to depths, the type of sediment on the sea floor was also catalogued. There was a cavity in the bottom of the weight, usually filled with tallow (rendered animal fat), which would pick up sediment upon hitting the bottom. When in well-traveled coastal waters a sailor's lead line showed (for example) ten fathoms and sand, he would have a fairly good idea of where he was in relation to the coast. Admittedly, knowing the type of sediment below is not very useful in a submarine ... but moderately accurate depths would undoubtedly have been available for the entire period of their use.