Aargh! My browser lost what I was typing!
Oh, well, Willeke beat me to it, and she said what I was going to say. And in fewer words (no surprise there).
But I'll go ahead and post a link to an article I found on
splices versus knots
at a site called Sailnet.com. Basically, anything you do to a rope will weaken it some, but splices weaken a rope far less than knots, because the stress on the rope is distributed over a greater length.
And here is a nice set of
instructions for putting an eye splice in a rope
.
As for the splice unravelling, it does not seem to be a problem. If you are really worried about it, you can probably whip the line after you splice it. But the guy who wrote the splicing instructions didn't say anything about keeping the splice together; I guess it just hangs together by itself.
Oh, and here is an
opinion on the usefulness of the bowline knot
,written from long sailing experience. I don't think a sling shakes a knot around as much as happens when wind meets boat, but still, we should each probably examine our slings frequently to see if anything is coming loose.