He could make out now some streaks of yellow light showing through the cracks one above the other along the side of the house and a dull patch of red.

He knew what it meant.

Bart and his fellows were inside, and were using one of the ship lanterns to see by.
This settled in his mind, the captain strode on, but at a slower pace.
He had found his bearings, and would steer with caution.
Hugging the dunes closer, he approached the house from the rear.

The big door was shut and a bit of matting had been tacked over the one window to deaden the light.

This was why the patch of red was dull.