The Structure of the Swallows and Amazons novels

The Swallows and Amazons novels is a series of twelve books written by Arthur Ransome between 1930 and 1945. It follows the adventures of John, Susan, Titty and Roger Walker (who sail in the dinghy Swallow) and Nancy and Peggy Blackett (who sail the Amazon) and, after the first three books, the Ds (Dick and Dorothea Callum who sail in the Scarab). The characters and settings vary with all eight children only together in Winter Holiday, Pigeon Post, and Great Northern? Most of the books are very realistic and are based on the activities children might be expected to do while on holiday; only Peter Duck and Missee Lee radically break this mould, both containing pirates; these books are characterised ad yarns that have been told to the author by some of the characters involved.

What makes these books unusual in children's fiction is their length (they are all over 300 pages in the Puffin paperback edition) and the large amounts of technical detail, mostly about sailing but also, among other things, birdwatching, map-making, prospecting, and trout tickling. These details add verisimilitude and make the reader believe in the story but a less-than-committed reader might well be discouraged by the sheer amount of reading needed. Yet they seem to be to be extremely readable. How has Ransome achieved this?

First, he gets rid of the adults (almost entirely, except as bit parts, with the exception of Captain Flint and the wonderfully villainous Great Aunt). This allows the children the chance to do grown-up things, camping alone, sailing, making fires. In several of the books there is real danger to their lives: including drowning (twice) shipwreck (twice) and being burned alive. But I think one of the ways in which Ransome keeps and holds one's attention is by the structure and pacing of his stories.

It seems to me that all the books follow the classic four-part structure:

The First Part contains the inciting incident, the call to action and ends with the first turning point which might equate the the awakening of the protagonists to the nature of their quest.
The Second Part ramps up the excitement and leads to a major turning point which might be called the moment of enlightenment.
The Third Part follows the logical consequences of what has already been initiated. It ends with a death experience.
The Fourth Part continues to explore the consequences. About half way through this part there is a moment of transformation followed by a climax; the resolution comes at the very end.

In a well-balanced novel each of these parts is the same size as the others; thus they divide the book up into quarters.