Tree rock
![](https://upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Baumnock.jpg/220px-Baumnock.jpg)
The tree jack of a Leisure 17
The tree jack is called the rear end of a tree on a (sailing) ship. A tree is used to attach the lower part of a sail, called the leech . Is it z. B. around the main boom (the tree to which the mainsail is attached), one speaks of the main boom .