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

--- a/net/minecraft/world/item/ItemBoat.java
+++ b/net/minecraft/world/item/ItemBoat.java
@@ -54,6 +54,13 @@
             }
 
             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.getBlockPosition(), movingobjectpositionblock.getDirection(), itemstack, enumhand);
+
+                if (event.isCancelled()) {
+                    return InteractionResultWrapper.pass(itemstack);
+                }
+                // CraftBukkit end
                 EntityBoat entityboat = new EntityBoat(world, movingobjectpositionblock.getPos().x, movingobjectpositionblock.getPos().y, movingobjectpositionblock.getPos().z);
 
                 entityboat.setType(this.b);
@@ -62,7 +69,15 @@
                     return InteractionResultWrapper.fail(itemstack);
                 } else {
                     if (!world.isClientSide) {
-                        world.addEntity(entityboat);
+                        // CraftBukkit start
+                        if (org.bukkit.craftbukkit.event.CraftEventFactory.callEntityPlaceEvent(world, movingobjectpositionblock.getBlockPosition(), movingobjectpositionblock.getDirection(), entityhuman, entityboat).isCancelled()) {
+                            return InteractionResultWrapper.fail(itemstack);
+                        }
+
+                        if (!world.addEntity(entityboat)) {
+                            return InteractionResultWrapper.pass(itemstack);
+                        }
+                        // CraftBukkit end
                         if (!entityhuman.abilities.canInstantlyBuild) {
                             itemstack.subtract(1);
                         }