In Number the Stars by Lois Lowry, what is the name of Uncle Henrik's boat and where did he get the name from?

Annemarie's Uncle Henrik was a fisherman.  He lived in a small fishing village on the northern shore of Denmark.  He owned a fishing boat "'named the Ingeborg.'"  He named his boat after Annemarie's mother, who was his sister and his only sibling.  At night and when Uncle Henrik was not using his boat, he kept it "'anchored in the harbor.'"  

The Ingeborg was very important in the story, and it was mentioned many times.  Uncle Henrik hid Jews under the floorboards at the bottom of the boat.  After they were hidden and the floorboards were covered with fish, he sailed his boat across to Sweden.  Sweden was not occupied by Nazis, so Danish Jews could live there in freedom.  Uncle Henrik was not the only fisherman who did this.  Other fisherman who disagreed with the Nazi mission of deporting Danish Jews also helped bring them to safety in Sweden.