C#

class DBStore
{
  public T CreateObject<T>()
  {
    ...
  }
  public void DeleteObject<T> (int id)
  {
     .. logic to delete from DB using metadata about T (containing table name) and primary key field matching 'id' ...
     .. eg.. delete from typeof(T).Name where ID = id
  }
}
abstract class DomainObject
{
  private int _id;
  private DBStore _dbStore;
  public void Delete ()
  {
    _dbStore.DeleteObject<<big>WHAT SHOULD GO HERE</big>>(_id)
  }
}
class Boat : DomainObject {...}
class Car : DomainObject {...}

Car car = new Car();
car.Delete();

Boat boat = new Boat();
boat.Delete();