The Spanish bowline can be used wherever it is desirable to have two eyes in the line. Its primary use, is a substitute for the boatswain's chair. Many prefer it to the French bowline because the bights are set and will not slip back and forth when the weight is shifted.
To tie this knot, take a bight and bend it back away from you, forming two bights. Then lap one bight over the other. Next, grab the two bights where they cross, and fold this part down toward you, forming four bights. Next, pass the bight on your lower left through the upper bight on your left. Next pass the bight on your lower right through the upper bight on your right.
To tie this knot, take a bight and bend it back away from you, forming two bights. Then lap one bight over the other. Next, grab the two bights where they cross, and fold this part down toward you, forming four bights. Next, pass the bight on your lower left through the upper bight on your left. Next pass the bight on your lower right through the upper bight on your right.
Adjust and pull tight, this will take some practice until you get the size of your bights the desired size.