OK, I've done a google search on "Sail Chalk Ginger Blue" and now have a number of theories for where the phrase came from:
1. Capt. Jode picked up the phrase while working at his father and uncle's shipyard in Richmond; the carpenters generally used blue chalk lines for outlining the ship's form on the floor of the mold loft. Ginger is a sharp spice; some would even say wicked sharp.

2. Ginger is indigenous to the West Indies and was often exported in distinctive white and blue jars with a sailing ship image on them; the local folks may have originated the term from the jars and Jode picked it up from them while trading in the West Indies.

3. It may have been derived from some form of rhyming slang; ginger beer, blue, and chalk.

4. It may be associated with the Blue Chalk Restaurant chain which features ginger in some of its sea food dishes.

5. There's a New Zealand orchid which has been described as "blue ginger" and very pretty.

6. In Queensland, AU, there's blue ginger fruit according to the Australia Insect Farm.

7. There was a "Ginger" on Gilligan's Island and "chalk talk" is a nautical phrase describing plotting courses on a chart.

Who knows, one of these suggestions might even be correct. My current favorite is #2.

Cheerily, Charley Noble