In reply to andy kirkpatrick:
This topic has been done to death a bit.
There is (n my opinion) a much better article on needlesports which talks in much more depth about the problem with a figure of 8, and also has test data comparing the fig 8 to both single and double overhand knots, and also mentions a couple of alternatives, such as fishermans, and a rethreaded figure of 8 such that the live rope on one side runs parallel to the tail on the other side