craftbukkit/nms-patches/net/minecraft/world/item/ItemBoat.patch

--- a/net/minecraft/world/item/ItemBoat.java
+++ b/net/minecraft/world/item/ItemBoat.java
@@ -58,6 +58,13 @@
             }
 
             if (movingobjectpositionblock.getType() == 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, movingobjectpositionblock.getBlockPos(), movingobjectpositionblock.getDirection(), itemstack, false, enumhand, movingobjectpositionblock.getLocation());
+
+                if (event.isCancelled()) {
+                    return InteractionResultWrapper.pass(itemstack);
+                }
+                // CraftBukkit end
                 EntityBoat entityboat = this.getBoat(world, movingobjectpositionblock);
 
                 entityboat.setVariant(this.type);
@@ -66,7 +73,15 @@
                     return InteractionResultWrapper.fail(itemstack);
                 } else {
                     if (!world.isClientSide) {
-                        world.addFreshEntity(entityboat);
+                        // CraftBukkit start
+                        if (org.bukkit.craftbukkit.event.CraftEventFactory.callEntityPlaceEvent(world, movingobjectpositionblock.getBlockPos(), movingobjectpositionblock.getDirection(), entityhuman, entityboat, enumhand).isCancelled()) {
+                            return InteractionResultWrapper.fail(itemstack);
+                        }
+
+                        if (!world.addFreshEntity(entityboat)) {
+                            return InteractionResultWrapper.pass(itemstack);
+                        }
+                        // CraftBukkit end
                         world.gameEvent((Entity) entityhuman, GameEvent.ENTITY_PLACE, movingobjectpositionblock.getLocation());
                         if (!entityhuman.getAbilities().instabuild) {
                             itemstack.shrink(1);