SELECT *
FROM sailboat
LEFT JOIN sailboat_type AS t2 ON ( t2.sailboat_type_id = barco_tipo )
LEFT JOIN sailboat_clase AS t3 ON ( t3.clase_id = barco_clase )
LEFT JOIN sailboat_paises AS t4, sailboat_timon AS t5, sailboat_bano AS t6 ON ( t4.pais_id = barco_bandera
AND t5.timon_id = barco_timon
AND t6.bano_id = barco_bano )