diff --git a/opm/core/simulator/BlackoilState.cpp b/opm/core/simulator/BlackoilState.cpp
index 1bd5341a..1f51dabb 100644
--- a/opm/core/simulator/BlackoilState.cpp
+++ b/opm/core/simulator/BlackoilState.cpp
@@ -17,4 +17,27 @@ BlackoilState::BlackoilState( size_t num_cells , size_t num_faces , size_t num_p
     registerCellData( GASOILRATIO , 1 );
     registerCellData( RV, 1 );
     registerCellData( SURFACEVOL, num_phases );
+    setBlackoilStateReferencePointers();
+}
+
+BlackoilState::BlackoilState( const BlackoilState& other )
+    : SimulationDataContainer(other)
+{
+    setBlackoilStateReferencePointers();
+}
+
+BlackoilState& BlackoilState::operator=( const BlackoilState& other )
+{
+    SimulationDataContainer::operator=(other);
+    setBlackoilStateReferencePointers();
+    return *this;
+}
+
+void BlackoilState::setBlackoilStateReferencePointers()
+{
+    // This sets the reference pointers for the fast
+    // accessors, the fields must have been created first.
+    gasoilratio_ref_ = &getCellData(GASOILRATIO);
+    rv_ref_          = &getCellData(RV);
+    surfacevol_ref_  = &getCellData(SURFACEVOL);
 }
diff --git a/opm/core/simulator/BlackoilState.hpp b/opm/core/simulator/BlackoilState.hpp
index ad2ba3d5..7f45e029 100644
--- a/opm/core/simulator/BlackoilState.hpp
+++ b/opm/core/simulator/BlackoilState.hpp
@@ -38,16 +38,41 @@ namespace Opm
         static const std::string RV;
         static const std::string SURFACEVOL;
 
-        BlackoilState(size_t num_cells , size_t num_faces, size_t num_phases);
+        /// Main constructor setting the sizes for the contained data
+        /// types.
+        /// \param num_cells   number of elements in cell data vectors
+        /// \param num_faces   number of elements in face data vectors
+        /// \param num_phases  number of phases, the number of components
+        ///                    in any data vector must equal 1 or this
+        ///                    number (this behaviour and argument is deprecated).
+        BlackoilState(size_t num_cells, size_t num_faces, size_t num_phases);
 
+        /// Copy constructor.
+        /// Must be defined explicitly because class contains non-value objects
+        /// (the reference pointers rv_ref_ etc.) that should not simply
+        /// be copied.
+        BlackoilState(const BlackoilState& other);
 
-        std::vector<double>& surfacevol  () { return getCellData("SURFACEVOL");  }
-        std::vector<double>& gasoilratio () { return getCellData(GASOILRATIO); }
-        std::vector<double>& rv ()          { return getCellData(RV);          }
+        /// Copy assignment operator.
+        /// Must be defined explicitly because class contains non-value objects
+        /// (the reference pointers rv_ref_ etc.) that should not simply
+        /// be copied.
+        BlackoilState& operator=(const BlackoilState& other);
+
+        std::vector<double>& surfacevol  () { return *surfacevol_ref_;  }
+        std::vector<double>& gasoilratio () { return *gasoilratio_ref_; }
+        std::vector<double>& rv ()          { return *rv_ref_;          }
+
+        const std::vector<double>& surfacevol  () const { return *surfacevol_ref_;  }
+        const std::vector<double>& gasoilratio () const { return *gasoilratio_ref_; }
+        const std::vector<double>& rv ()          const { return *rv_ref_;          }
+
+    private:
+        void setBlackoilStateReferencePointers();
+        std::vector<double>* surfacevol_ref_;
+        std::vector<double>* gasoilratio_ref_;
+        std::vector<double>* rv_ref_;
 
-        const std::vector<double>& surfacevol  () const { return getCellData("SURFACEVOL");  }
-        const std::vector<double>& gasoilratio () const { return getCellData("GASOILRATIO"); }
-        const std::vector<double>& rv ()          const { return getCellData(RV);          }
 
     };
 } // namespace Opm