screw log vs taffrail log

screw log and taffrail log both are nouns.

Word	Noun	Adjective	Verb	Adverb
screw log	Yes	No	No	No
taffrail log	Yes	No	No	No

As nouns, screw log and taffrail log are synonyms defined as:

screw log and taffrail log: a cigar-shaped log with rotary fins that measure the ship's speed

Other synonyms of screw log include patent log.

screw log (noun)	taffrail log (noun)
a cigar-shaped log with rotary fins that measure the ship's speed	a cigar-shaped log with rotary fins that measure the ship's speed