The Australian Plait aka Australian Braid knot is an excellent method to create a strong low profile double line using mono or fluorocarbon.
Also used as an alternative for the Bimini Twist.
Knot strength 100% @AnglingKnots
Check out the easy to follow step-by-step knot illustrations in the publications:
Fishing Knots – From the reel to the hook:
Fishing Knots & Rigs:
The Fishing Knots Posters:
https://fish-and-bits.myspreadshop.co.uk/all
or
https://fineartamerica.com/featured/1-fishing-knots-andy-steer.html
Disclaimer:
No responsibility in any way is accepted for incidents arising from the use of this material.