The Herringbone Interweave
Probably the best reason for using a turkshead foundation and interweaving a second into it is the color patterns you can achieve by using different colors for each knot as there are easier methods of braiding these codings with a single string in one knot. The herringbone coding results in the color bands running around the circumference of the body of the knot in contrast to those lengthwise across the knot as in the gaucho coding. As with the simple pineapples we are limited to odd part knots for the foundation but this interweave results in the second knot having the same number of parts as the foundation.
A 7 X 5 Knot
The first wrap of the herring bone pattern for common bight boundaries begins by entering the foundation (blue) with a single under crossing. Then count the two pass coding as O-2 U-2 etc to the top of the knot with an U-2 exit. The second half of the wrap is a repetition of the first half (U-1 O-2 etc) always including the vacant spaces in the count. This establishes the required parallel path to the left (or on the right) of a part of the foundation. The single under beginning the second half of the wrap maintains this parallel status to a part on the same side of the running end. The main reason for this perspective of the count sequence is to mentally place the crossings of the vacant spaces in the over or under order that they will actually occur in the final braid pattern. In fact you can see that the second half of this first wrap crossed itself in the proper way tosplit a pair and at a space we had counted as an under in the first half.
Here are the second and third wrap. Placed in exactly the same manner they continue to develope the proper braid pattern without any real mental effort on our part except to maintain the same "count" for each pass. By now it is obvious that we are "nesting" the bights of the interweave behind the crosses between the bights of the foundation. This is one level past the nesting we used for the simple pineapple and some would contend that this is a pineapple also. This is probably a matter of semantics and I will not dispute the matter. In fact when the knot is properly tightened the bights of the interweave will be partly or completely hidden by this nesting depending on the material used to braid the knot.
These are the last two wraps of the five needed for a five bight second knot. You might observe that it is in the last wrap that we finally fill all of the vacant spaces in the pattern count.
This is a completed view of the knot so you can see the color pattern in it's entirity.
If you are wondering why I chose this particular knot for an example so often there are several reasons. For one thing the five bight turksheads (as all odd bight knots do) allow a finer step in length than the even bight "standard" versions. This 7 X 5 knot having an apparent bight progression of two pins allows the true braid structure to develop with out displaying some of the other "patterns in sequence" noticable in some knots that are unique to some of them but not germane to others. You may see what I am refering to in the next examples but to avoid confusion I will not point them out. In another context I will explain them and how to use them for another purpose.