A string vest synopsis

I have dragged my old syjnopsis for TSD out, and immediately wish I hadn't. it was supposed to serve as an aide-memoire but I immediately thought what was I thinking? I should have put more in.
As far as sketches go, this is pencil light, the merest hint of a story. The sum total of the middle bit is -- he saves some people in a storm. Huh? Why did not I not write more? Why did I not write a full tow page outline to give me something to go on (generally too much ast this stage) but something concrete.
I can tell by reading the first three chapters,I had a lot more ideas. Luckily I will be able to pick up on those, but it does annoy me when I thought I had been clever and mapped out the book to find it moth eaten and currently string vest like.
So now I shall have to take the time and rewrite this. Then write the rest. I normally write my first version of the synopsis at about the end of chapter 3. It gives me something to go on. I know the characters then. I know where their motivations are heading. I know the basic outline. It is time well spent in general because the actual writing goes much quicker. Once it is done, a copy sits on my desk, becoming increasingly stained with coffee rings, tea splodges and cryptic notations. Even down to circling phrases and writing ch 7/8. It may not work for most people but it does work for me.
However, I thought maybe I had done the work last summer but no way. I shall have to put my thinking cap on again and come up with a few better twists.
Luckily the Donald Maas Breakout Workbook has a few exercises for developing plot twists, turns and layers.
This can be a good book. I can feel that in my bones. I would like to make it be the best it can be.