This is a sailing vessel. The rectangular hole you see at the waterline, almost at the rear of the ship, can contain a big-sized lorry from left to right, or vice versa.
This picture was taken in Cartagena. This is no surprise because Melnichenko is a very good friend of Putin and Cartagena is a submarine port of the Spanish navy. A few weeks earlier this yacht was spotted near Gibraltar during a huge international, water and air combined, military exercise.