The Water Bowline and the Dble Bwl are variations of a basic Bwl in which an extra half hitch is added. The difference depends on which half hitch lies on top of the other.
It's an extra TURN in the Dble.Bwl, not a HH. The additional security
that provides is partly in that whatever slight loosening might
come will be allocated over the two vs. a single turn; and the
round turn (another name for it--"RT Bwl") will better grip the collar legs
Based on the above links, roo feels that the Double Bowline isn't quite as secure as the Water Bowline. Is this the general consensus? Is the end of the rope fairly well "locked" with either of these forms of the Bowline?
I concur in Roo's assessment, ASSUMING that one takes the "Water
Bwl" to be essentially a Bwl using a Clove vs. HHitch in the SPart;
it is otherwise sometimes shown with this extra HH spaced at some
remove from the main knot (and I might suggest that the source even had
really tied off some object--"hitchec" we might say--with a simple
knot which became capsized into this HH, and the point being
to better snug the loop eye to the object. (This is something
along the lines of what Cyrus Day muses in his attempt to figure out
the point of the knot. Budworth seems to be one who has made it
a point to put the extra HH up snug with the knot. As such, with
some working when setting the knot, one can gain security.
My guess it that the Dbl (aka "Round Turn") Bwl is stronger.
As for locking, I've already suggested better ways to lock a Bwl; see above.
Again, esp. with the Dbl.Bwl form, look at the 4th, "rear view side"
image of the single Bwl shown on Dan Britton's site:www.iland.net/~jbritton/bowline.htm
Notice where the SPart crosses UNDER itself informing that collar-nipping
part of the knot, before it then flows into the eye. That's where one
would like to bind the knot with the end! So, simply bring the end (as
oriented in the "rear view" image) back down OVER this crossing,
and then re-tuck (don't untuck to begin--just continue from the
regular form!) the end beside itself; tighten this end-turn,
tighten the SPart's turn; repeat ... .
For a truly added HH, with the end, again from the position above
("rear view") take the end Over to the right and around in
making a HH around BOTH legs of the eye; tuck (to make it a HH)
under itself (end) AND through the loop of the SPart, which puts
one more piece of rope to hold the end.