I tie easy 18" double line bimini twists by using the reel handle of my spinning reel as a third hand. basically I pull enough line off the spool to reach about 2' past the base of the rod I am using, twist 20-25 twists in the line by looping it over two
of my fingers and swirling my wrist rapidly.
When the line is twisted 25 times I hook the loop over the rod handle, slide y thumb op the loop to put tension on it and with the other hand lock off the top of the twist w/ a single clinch knot. Then I tie a 3 or 4 turn clinch knot above that knot to
lock it off.
30-seconds to 1 minute tops.