Full Idea
If we say that up to 5% of a ship's parts can be replaced without the ship ceasing to exist, we could replace 4% and then 4% again, and it would retain its identity, if identity is transitive.
Clarification
Identity is 'transitive' means if a is b, and b is c, the a must be c
Gist of Idea
If 5% replacement preserves a ship, we can replace 4% and 4% again, and still retain the ship
Source
E.J. Lowe (A Survey of Metaphysics [2002], p.26)
Book Reference
Lowe,E.J.: 'A Survey of Metaphysics' [OUP 2002], p.26
A Reaction
One suspected that all attempts at precision with the ship of Theseus were doomed, but this nicely demonstrates it.