Updated to 1.21.1
Thanks Nacolla and Ninni for the help!
Updates
Fixes
Fixed walking on hullback mechanic
The ship can now be equipped with all types of vanilla planks
New interaction with boat and chest boat items is now possible
Sails can now be interacted with with a banner to apply its patterns to the sail
Anchors can now be placed on blocks, right clicked or shift right clicked to change its facing angle
Using an axe on a hullback will now drop rough barnacles, a new decorative block that can be stacked up to three times in one block space Using two rough barnacles in a crafting grid will give you a barnacle, which can be stacked up to 9 blocks high to create organ like musical notes
Added a new client config to address the shader incompatibility

Adds a new hullback mob and pirate ship mechanics