>>1377731You need... 6 knots for everything
1) Figure-eight knot
2) Cleat knot
3) Fisherman mooring knot (along with 3a, the double half-knot)
4) Reef knot
5) Bowline knot
6) Hunter's knot
Now, I have no idea if those are proper English names for 3 and 3a, so pic related for comparison. Someone please identify those and name them properly.
Theoretically, if you know 1, 2, 4 and 5, you can to EVERYTHING with those. 3 and 3a are handy if you can't exactly have the ear from bowline knot for one or another reason. Meanwhile, Hunter's knot is probably the best way of connecting two ropes, especially broken ones (even steel ones) that can be then easily untied by "breaking" it.
But seriously, I know people who sailed the world knowing just 1, 2 and 5. On the other hand, you must be absolutely and positively 100% you can tie bowline knot even if you are blind, drunk and bleeding to death. Because otherwise that knot is useless if you fuck it up.
