Seat

EntitySeat.java

package leviathan143.wildblueyonder.common.watercraft.entities;

import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.util.EnumHand;
import net.minecraft.world.World;

public class EntitySeat extends EntityWatercraftPart
{
    public EntitySeat(World world)
    {
	super(world);
	this.setSize(0.5F, 0.5F);
    }

    public EntitySeat(EntityWatercraft parent, int deckX, int deckZ)
    {
	super(parent, deckX, deckZ);
	this.setSize(0.5F, 0.5F);
    }
    
    @Override
    public double getMountedYOffset()
    {
        return super.getMountedYOffset() - 0.3F;
    }

    @Override
    public boolean processInitialInteract(EntityPlayer player, EnumHand hand)
    {
	if (player.isSneaking())
	{
	    return false;
	}
	else
	{
	    if (!this.world.isRemote)
	    {
		player.startRiding(this, true);
	    }

	    return true;
	}
    }
}

EntityWaterCraftPart.java

package leviathan143.wildblueyonder.common.watercraft.entities;

import net.minecraft.entity.Entity;
import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.util.math.Vec3d;
import net.minecraft.world.World;

public class EntityWatercraftPart extends Entity
{
    private static final String DECK_X = "deck_x";
    private static final String DECK_Z = "deck_z";

    private EntityWatercraft parent;
    private Vec3d basePosition = new Vec3d(0, 0, 0);
    private Vec3d pos;

    public EntityWatercraftPart(EntityWatercraft parent, int deckX, int deckZ)
    {
	super(parent.world);
	this.parent = parent;
	basePosition = new Vec3d(deckX, 0.0D, deckZ);
    }

    public EntityWatercraftPart(World world)
    {
	super(world);
    }

    @Override
    protected void entityInit()
    {}

    @Override
    public boolean canBeCollidedWith()
    {
	return true;
    }
    
    public void rotateYaw(float yaw)
    {
	pos = basePosition.rotateYaw((float) Math.toRadians(yaw));
    }
    
    public Vec3d getPos()
    {
	return pos;
    }
    
    @Override
    protected void readEntityFromNBT(NBTTagCompound nbt)
    {
	if(this.getRidingEntity() instanceof EntityWatercraft)
	    this.parent = (EntityWatercraft) this.getRidingEntity();
	this.basePosition = new Vec3d(nbt.getInteger(DECK_X), 0, nbt.getInteger(DECK_Z));
    }

    @Override
    protected void writeEntityToNBT(NBTTagCompound nbt)
    {
	nbt.setInteger(DECK_X, (int) basePosition.xCoord);
	nbt.setInteger(DECK_Z, (int) basePosition.zCoord);
    }
}

ModEntities.java

package leviathan143.wildblueyonder.common.core;

import leviathan143.wildblueyonder.common.core.WildBlueYonder.Constants;
import leviathan143.wildblueyonder.common.watercraft.entities.*;
import net.minecraft.entity.Entity;
import net.minecraft.util.ResourceLocation;
import net.minecraftforge.fml.common.registry.EntityRegistry;

public class ModEntities 
{
	private static int entityID = 0; 
	
	public static void register()
	{
		//Same as the vanilla boat
		registerEntity(EntityWatercraft.class, "watercraft", 80, 3, true);
		registerEntity(EntitySeat.class, "seat", 80, 3, true);
	}
	
	private static void registerEntity(Class<? extends Entity> entityClass, String entityName, int trackingRange, int updateFrequency, boolean sendsVelocityUpdates)
	{
		EntityRegistry.registerModEntity(new ResourceLocation(Constants.MODID, entityName), entityClass, entityName, entityID, WildBlueYonder.instance, trackingRange, updateFrequency, sendsVelocityUpdates);
		entityID++;
	}
}