I don't know what the scale works out to, but we're talking 1:350 at least If I'm not mistaken.
Bear with me for a moment:
Shipbucket scale is 2 pixels per foot.
Standard pixel density is about 72 to 96 DPI.
This means that an inch in Shipbucket scale is 36-48 feet.
This means that a foot in Shipbucket scale is 432 to 648 feet.
So a scale of 1:430-650 is a good round spec.