by Swing Swang » Mon Aug 17, 2015 2:19 pm
Essentially a bubble knot is a casing tied into a reef/granny knot - if you modify this slightly to a surgeon's-type knot, wrapping the casing around the string a couple of times before you tie the second part of the know you should be very secure.
Another thing that worked for me is to not be too frugal with the empty bit of casing. A couple of cm (or more) is much easier to tie into a bubble knot than 5mm until you get the hand of it.
So, in words, this is my modification:
Instead of the first overhand knot (i.e. the 'left over right' bit in reef knot terminology) wrap the 'left' around around the 'right' TWICE and pull tight. The extra turn gives a tighter first part. and the extra friction stops the knot working loose whilst you let go and reposition your hands to finish the knot off.
Then wrap the casing TWICE around one of the standing parts (i.e. the bit that you are holding in either your left or your right hand) - you are not forming a knot with the casing and the string, just twisting them around each other, and this gets worked/jammed into the final overhand knot - if you're really cautious you could wrap the casing round a few more times just for good measure! Ensure the twisted casing is snug against that the first overhand knot.
The tie another overhand knot (in boy scouts' terminology that's the 'left over right' bit to finish off.
Much quicker to do than to describe, and quite secure enough for my needs.