PaperMC/paper-server/patches/sources/net/minecraft/world/item/BoatItem.java.patch

--- a/net/minecraft/world/item/BoatItem.java
+++ b/net/minecraft/world/item/BoatItem.java
@@ -58,6 +58,13 @@
             }
 
             if (movingobjectpositionblock.getType() == HitResult.Type.BLOCK) {
+                // CraftBukkit start - Boat placement
+                org.bukkit.event.player.PlayerInteractEvent event = org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerInteractEvent(user, org.bukkit.event.block.Action.RIGHT_CLICK_BLOCK, movingobjectpositionblock.getBlockPos(), movingobjectpositionblock.getDirection(), itemstack, false, hand, movingobjectpositionblock.getLocation());
+
+                if (event.isCancelled()) {
+                    return InteractionResult.PASS;
+                }
+                // CraftBukkit end
                 AbstractBoat abstractboat = this.getBoat(world, movingobjectpositionblock, itemstack, user);
 
                 if (abstractboat == null) {
@@ -68,7 +75,15 @@
                         return InteractionResult.FAIL;
                     } else {
                         if (!world.isClientSide) {
-                            world.addFreshEntity(abstractboat);
+                            // CraftBukkit start
+                            if (org.bukkit.craftbukkit.event.CraftEventFactory.callEntityPlaceEvent(world, movingobjectpositionblock.getBlockPos(), movingobjectpositionblock.getDirection(), user, abstractboat, hand).isCancelled()) {
+                                return InteractionResult.FAIL;
+                            }
+
+                            if (!world.addFreshEntity(abstractboat)) {
+                                return InteractionResult.PASS;
+                            }
+                            // CraftBukkit end
                             world.gameEvent((Entity) user, (Holder) GameEvent.ENTITY_PLACE, movingobjectpositionblock.getLocation());
                             itemstack.consume(1, user);
                         }