Paper/nms-patches/ItemBoat.patch

--- a/net/minecraft/server/ItemBoat.java
+++ b/net/minecraft/server/ItemBoat.java
@@ -52,6 +52,13 @@
             if (flag) {
                 return new InteractionResultWrapper(EnumInteractionResult.PASS, itemstack);
             } else if (movingobjectposition.type == MovingObjectPosition.EnumMovingObjectType.BLOCK) {
+                // CraftBukkit start - Boat placement
+                org.bukkit.event.player.PlayerInteractEvent event = org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerInteractEvent(entityhuman, org.bukkit.event.block.Action.RIGHT_CLICK_BLOCK, movingobjectposition.a(), movingobjectposition.direction, itemstack, enumhand);
+
+                if (event.isCancelled()) {
+                    return new InteractionResultWrapper(EnumInteractionResult.PASS, itemstack);
+                }
+                // CraftBukkit end
                 BlockPosition blockposition = movingobjectposition.a();
                 Block block = world.getType(blockposition).getBlock();
                 EntityBoat entityboat = new EntityBoat(world, movingobjectposition.pos.x, movingobjectposition.pos.y, movingobjectposition.pos.z);
@@ -62,7 +69,7 @@
                     return new InteractionResultWrapper(EnumInteractionResult.FAIL, itemstack);
                 } else {
                     if (!world.isClientSide) {
-                        world.addEntity(entityboat);
+                        if (!world.addEntity(entityboat)) return new InteractionResultWrapper(EnumInteractionResult.PASS, itemstack); // CraftBukkit
                     }
 
                     if (!entityhuman.abilities.canInstantlyBuild) {